View Filing Data

Print Document View Excel Document

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2018	Feb. 21, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	TRXC
Entity Registrant Name	TRANSENTERIX INC.
Entity Central Index Key	0000876378
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		217,014,383
Entity Public Float			$ 715.7

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 21,061	$ 91,217
Short-term investments	51,790
Accounts receivable, net	8,560	1,536
Inventories	10,941	10,817
Interest receivable	26	80
Other current assets	9,205	9,344
Total Current Assets	101,583	112,994
Restricted cash	590	6,389
Property and equipment, net	6,337	6,670
Goodwill	80,131	71,368
Other long term assets	203	192
Total Assets	239,307	250,251
Current Liabilities
Accounts payable	4,433	3,771
Accrued expenses	9,619	10,974
Deferred revenue – current portion	1,733	1,088
Deferred gain on sale of SurgiBot assets		7,500
Contingent consideration – current portion	72	719
Deferred consideration - MST Acquisition	5,962
Notes payable – current portion, net of debt discount		4,788
Total Current Liabilities	21,819	28,840
Long Term Liabilities
Deferred revenue – less current portion	109
Contingent consideration – less current portion	10,565	11,699
Notes payable – less current portion, net of debt discount	28,937	8,385
Warrant liabilities	4,636	14,090
Net deferred tax liabilities	4,720	8,389
Total Liabilities	70,786	71,403
Commitments and Contingencies
Stockholders’ Equity
Common stock $0.001 par value, 750,000,000 shares authorized at December 31, 2018 and 2017, respectively; 216,345,984 and 199,282,003 shares issued and outstanding at December 31, 2018 and 2017, respectively	216	199
Additional paid-in capital	676,373	621,261
Accumulated deficit	(509,406)	(447,640)
Accumulated other comprehensive income	1,338	5,028
Total Stockholders’ Equity	168,521	178,848
Total Liabilities and Stockholders’ Equity	239,307	250,251
Intellectual Property, Net [Member]
Current Assets
Intangible assets	39,716	$ 52,638
In-Process Research and Development [Member]
Current Assets
Intangible assets	$ 10,747

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement Of Partners Capital [Abstract]
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	750,000,000	750,000,000
Common stock, shares issued	216,345,984	199,282,003
Common stock, shares outstanding	216,345,984	199,282,003

Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Revenue	$ 24,102,000	$ 7,111,000	$ 1,519,000
Cost of revenue	16,171,000	6,727,000	1,069,000
Gross profit	7,931,000	384,000	450,000
Operating Expenses (Income)
Research and development	21,823,000	21,989,000	29,273,000
Sales and marketing	25,736,000	17,536,000	9,151,000
General and administrative	13,854,000	12,275,000	10,813,000
Amortization of intangible assets	10,868,000	7,858,000	6,967,000
Change in fair value of contingent consideration	(1,011,000)	2,026,000	482,000
Issuance costs for warrants		627,000
Inventory write-down related to restructuring			2,565,000
Restructuring and other charges			3,064,000
Goodwill impairment	0	0	61,784,000
Acquisition related costs	647,000
Gain from sale of SurgiBot assets, net	(11,840,000)
Reversal of transfer fee accrual	(2,994,000)
Total Operating Expenses (Income)	57,083,000	62,311,000	124,099,000
Operating Loss	(49,152,000)	(61,927,000)	(123,649,000)
Other (Expense) Income
Change in fair value of warrant liabilities	(14,320,000)	(83,734,000)
Interest income	1,400,000	308,000	132,000
Interest expense	(4,208,000)	(2,443,000)	(2,021,000)
Other income (expense)	1,126,000	(300,000)	35,000
Total Other (Expense) Income, net	(16,002,000)	(86,169,000)	(1,854,000)
Loss before income taxes	(65,154,000)	(148,096,000)	(125,503,000)
Income tax benefit	3,377,000	3,300,000	5,523,000
Net loss	(61,777,000)	(144,796,000)	(119,980,000)
Comprehensive loss
Foreign currency translation (loss) gain	(3,690,000)	10,797,000	(2,603,000)
Comprehensive loss	$ (65,467,000)	$ (133,999,000)	$ (122,583,000)
Net loss per share - basic and diluted	$ (0.30)	$ (0.97)	$ (1.07)
Weighted average common shares outstanding - basic and diluted	207,199	148,744	112,185

Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive (Loss) Income [Member]
Balance at Dec. 31, 2015	$ 177,277	$ 100	$ (73)	$ 363,280	$ (182,864)	$ (3,166)
Balance, Shares at Dec. 31, 2015		100,180	(31)
Stock-based compensation	5,033			5,033
Issuance of common stock, net of issuance costs	58,029	$ 15		58,014
Issuance of common stock, net of issuance costs, Shares		15,086
Exercise of stock options and restricted stock units	166			166
Exercise of stock options and restricted stock units, Shares		419
Return of common stock to pay withholding taxes on restricted stock	(168)		$ (168)
Return of common stock to pay withholding taxes on restricted stock, Shares			(63)
Issuance of common stock for services	116			116
Issuance of common stock for services, Shares		96
Other comprehensive loss	(2,603)					(2,603)
Net loss	(119,980)				(119,980)
Balance at Dec. 31, 2016	117,870	$ 115	$ (241)	426,609	(302,844)	(5,769)
Balance, Shares at Dec. 31, 2016		115,781	(94)
Stock-based compensation	7,078			7,078
Non-employee warrant awards	838			838
Issuance of common stock and treasury stock, net of issuance costs	68,864	$ 45	$ 409	68,410
Issuance of common stock and treasury stock, net of issuance costs, Shares		44,689	213
Exercise of stock options and warrants	112,838	$ 35		112,803
Exercise of stock options and warrants, Shares		34,749
Award of restricted stock units, Shares		340
Return of common stock to pay withholding taxes on restricted stock	(168)		$ (168)
Return of common stock to pay withholding taxes on restricted stock, Shares			(119)
Issuance of common stock in exchange for contingent consideration	5,227	$ 4		5,223
Issuance of common stock in exchange for contingent consideration, Shares		3,723
Relative fair value of warrants issued with debt	300			300
Other comprehensive loss	10,797					10,797
Net loss	(144,796)				(144,796)
Balance at Dec. 31, 2017	178,848	$ 199		621,261	(447,640)	5,028
Balance, Shares at Dec. 31, 2017		199,282
Stock-based compensation	9,039			9,039
Issuance of common stock and warrants, net of issuance costs	279			279
Issuance of common stock for MST Acquisition	8,300	$ 3		8,297
Issuance of common stock for MST acquisition, Shares		3,150
Exercise of stock options and warrants	36,173	$ 12		36,161
Exercise of stock options and warrants, Shares		11,559
Award of restricted stock units	1	$ 1
Award of restricted stock units, Shares		1,069
Return of common stock to pay withholding taxes on restricted stock	(1,662)		$ 1	(1,663)
Return of common stock to pay withholding taxes on restricted stock, Shares			537
Cancellation of treasury stock	(1)		$ (1)
Cancellation of treasury stock, Shares			(537)
Issuance of common stock related to sale of SurgiBot assets	3,000	$ 1		2,999
Issuance of common stock related to sale of SurgiBot assets, Shares		1,286
Cumulative effect of change in accounting principle (Note 2)	11				11
Other comprehensive loss	(3,690)					(3,690)
Net loss	(61,777)				(61,777)
Balance at Dec. 31, 2018	$ 168,521	$ 216		$ 676,373	$ (509,406)	$ 1,338
Balance, Shares at Dec. 31, 2018		216,346

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
Consolidated Statements of Cash Flows - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Activities
Net loss	$ (61,777,000)	$ (144,796,000)	$ (119,980,000)
Adjustments to reconcile net loss to net cash and cash equivalents used in operating activities:
Gain from sale of SurgiBot assets, net	(11,840,000)
Depreciation	2,420,000	2,486,000	1,942,000
Amortization of intangible assets	10,868,000	7,858,000	6,967,000
Amortization of debt discount and debt issuance costs	725,000	510,000	177,000
Amortization of short-term investment discount	(351,000)
Stock-based compensation	9,039,000	7,078,000	5,033,000
Non-employee warrant awards		838,000
Common stock issued for services			116,000
Inventory write-down related to restructuring			2,565,000
Non-cash restructuring and other charges			2,556,000
Goodwill impairment	0	0	61,784,000
Deferred tax benefit	(3,377,000)	(3,300,000)	(5,562,000)
Loss on extinguishment of debt	1,400,000	308,000
Change in fair value of warrant liabilities	14,320,000	83,734,000
Change in fair value of contingent consideration	(1,011,000)	2,026,000	482,000
Reversal of transfer fee accrual	(2,994,000)
Changes in operating assets and liabilities, net of effect of acquisition:
Accounts receivable	(7,225,000)	(381,000)	(1,041,000)
Interest receivable	54,000	23,000	(6,000)
Inventories	(2,145,000)	(2,981,000)	(6,647,000)
Other current and long term assets	(325,000)	(3,348,000)	(1,528,000)
Accounts payable	767,000	(531,000)	(356,000)
Accrued expenses	2,134,000	2,093,000	1,112,000
Deferred revenue	825,000	1,088,000
Net cash and cash equivalents used in operating activities	(48,493,000)	(47,295,000)	(52,386,000)
Investing Activities
Purchase of short-term investments	(55,439,000)
Proceeds from maturities of short-term investments	4,000,000
Payment for acquisition of a business	(5,800,000)
Proceeds related to sale of SurgiBot assets, net	4,496,000	7,500,000
Purchase of property and equipment	(770,000)	(1,566,000)	(1,361,000)
Purchase of intellectual property		(425,000)
Proceeds from sale of property and equipment	32,000
Net cash and cash equivalents (used in) provided by investing activities	(53,481,000)	5,509,000	(1,361,000)
Financing Activities
Payment of notes payable	(15,305,000)	(13,343,000)	(6,902,000)
Proceeds from issuance of debt and warrants, net of issuance costs	28,507,000	13,005,000
Payment of contingent consideration	(770,000)	(7,181,000)	(1,182,000)
Proceeds from issuance of common stock and warrants, net of issuance costs	279,000	77,579,000	58,029,000
Taxes paid related to net share settlement of vesting of restricted stock units	(1,662,000)	(168,000)	(168,000)
Proceeds from issuance of common stock related to sale of SurgiBot assets	3,000,000
Proceeds from exercise of stock options and warrants	12,403,000	34,479,000	166,000
Net cash and cash equivalents provided by financing activities	26,452,000	104,371,000	49,943,000
Effect of exchange rate changes on cash and cash equivalents	(433,000)	431,000	(55,000)
Net (decrease) increase in cash, cash equivalents and restricted cash	(75,955,000)	63,016,000	(3,859,000)
Cash, cash equivalents and restricted cash, beginning of period	97,606,000	34,590,000	38,449,000
Cash, cash equivalents and restricted cash, end of period	21,651,000	97,606,000	34,590,000
Supplemental Disclosure for Cash Flow Information
Interest paid	1,730,000	899,000	1,289,000
Supplemental Schedule of Noncash Investing and Financing Activities
Transfer of inventories to property and equipment	2,160,000	1,258,000	$ 3,198,000
Transfer of property and equipment to inventories	637,000
Issuance of common stock as contingent consideration		5,227,000
Relative fair value of warrants issued with debt		300,000
Reclass of warrant liability to common stock and additional paid in capital	23,774,000	78,359,000
Transfer of in-process research and development to intellectual property		17,913,000
Cashless exercise of warrants	4,272,000	$ 149,000
Issuance of common stock related to acquisition	8,300,000
Deferred consideration - MST acquistion	$ 5,962,000

Organization and Capitalization

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Organization and Capitalization

1.	Organization and Capitalization

TransEnterix is a medical device company that is digitizing the interface between the surgeon and the patient in laparoscopy to increase control and reduce surgical variability in today’s value-based healthcare environment. The Company is focused on the commercialization of the Senhance™ System, that digitizes laparoscopic minimally invasive surgery. The Senhance System allows for robotic precision, haptic feedback, surgeon camera control via eye sensing and improved ergonomics while offering responsible economics.

The Senhance System has a CE Mark in Europe for laparoscopic abdominal and pelvic surgery, as well as limited thoracic operations excluding cardiac and vascular surgery. On October 13, 2017, the Company received 510(k) clearance from the FDA for use of the Senhance System in laparoscopic colorectal and gynecologic surgery. These indications cover 23 procedures, including benign and oncologic procedures. In May 2018, the indications for use expanded when the Company received 510(k) clearance from the FDA for use of the Senhance System in laparoscopic inguinal hernia and laparoscopic cholecystectomy (gallbladder removal) surgery for a total of 28 indicated procedures. The Senhance System is available for sale in the U.S., the EU and select other countries.

The Senhance System is a multi-port robotic surgery system that allows multiple robotic arms to control instruments and a camera. The system features advanced technology to enable surgeons with haptic feedback and the ability to move the camera via eye movement.

On October 31, 2018, the Company acquired the assets, intellectual property and highly experienced multidisciplinary personnel of Israel-based MST Medical Surgical Technologies, Inc., or MST. Through this acquisition the Company acquired MST’s AutoLap™ technology, one of the only image-guided robotic scope positioning systems with FDA clearance and CE Mark. The Company believes MST’s image analytics technology will accelerate and drive meaningful Senhance System developments, and allow it to expand the Senhance System to add augmented, intelligent vision capability. See Note 3 for a description of the related transaction.

During 2018 and early 2019, the Company successfully obtained FDA clearance and CE Mark for 3 millimeter diameter instruments and its Senhance ultrasonic system. The 3 mm instruments enable the Senhance System to be used for microlaparoscopic surgeries, allowing for tiny incisions, and the ultrasonic system is an advanced energy device used to deliver controlled energy to ligate and divide tissue, while minimizing thermal injury to surrounding structures.

The Company has also developed the SurgiBot System, a single-port, robotically enhanced laparoscopic surgical platform. In December 2017, the Company entered into an agreement with Great Belief International Limited, or GBIL, to advance the SurgiBot System towards global commercialization. The agreement transferred ownership of the SurgiBot System assets, while the Company retained the option to distribute or co-distribute the SurgiBot System outside of China. GBIL intends to have the SurgiBot System manufactured in China and obtain Chinese regulatory clearance from the China Food and Drug Administration while entering into a nationwide distribution agreement with China National Scientific and Instruments and Materials Company, or CSIMC, for the Chinese market. The agreement provides the Company with proceeds of at least $29.0 million, of which $15.0 million has been received to date. The remaining $14.0 million, representing minimum royalties, will be paid beginning at the earlier of receipt of Chinese regulatory approval or March 2023.

On September 18, 2015, the Company entered into a Membership Interest Purchase Agreement, (the “Purchase Agreement”) with Sofar S.p.A., (“Sofar”) as seller, Vulcanos S.r.l. (“Vulcanos”), as the acquired company, and TransEnterix International, Inc. (“TransEnterix International”), a direct, wholly owned subsidiary of the Company which was incorporated in September 2015, as buyer. The closing of the transactions occurred on September 21, 2015 (the “Closing Date”) pursuant to which the Company acquired all of the membership interests of Vulcanos from Sofar (now known as the “Senhance Acquisition”), and changed the name of Vulcanos to TransEnterix Italia S.r.l (“TransEnterix Italia”). The Senhance Acquisition included all of the assets, employees and contracts related to the Senhance System. See Note 3 for a description of the related transactions.

On September 3, 2013, TransEnterix Surgical, Inc. a Delaware corporation (“TransEnterix Surgical”), and SafeStitch Medical, Inc., a Delaware corporation (“SafeStitch”) consummated a merger transaction whereby TransEnterix Surgical merged with a merger subsidiary of SafeStitch, with TransEnterix Surgical as the surviving entity in the merger (the “Merger”). As a result of the Merger, TransEnterix Surgical became a wholly owned subsidiary of SafeStitch. On December 6, 2013, SafeStitch changed its name to TransEnterix, Inc. and increased the authorized shares of common stock from 225,000,000 to 750,000,000, and authorized 25,000,000 shares of preferred stock, par value $0.01 per share.

As used herein, the term “Company” refers to the combination of SafeStitch and TransEnterix Surgical after giving effect to the Merger, and includes TransEnterix International, Inc.; TransEnterix Italia S.r.l.; TransEnterix Europe S.à.R.L; TransEnterix Asia Pte. Ltd.; TransEnterix Taiwan Ltd.; TransEnterix Japan KK and TransEnterix Israel Ltd.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2.	Summary of Significant Accounting Policies

Basis of Presentation

The accompanying Consolidated Financial Statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) and include the accounts of the Company and its direct and indirect wholly owned subsidiaries, SafeStitch LLC, TransEnterix Surgical, Inc., TransEnterix International, Inc., TransEnterix Italia S.r.l., TransEnterix Europe S.Á.R.L; TransEnterix Asia Pte. Ltd.; TransEnterix Taiwan Ltd.; TransEnterix Japan KK and TransEnterix Israel Ltd. All inter-company accounts and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Significant items subject to such estimates and assumptions include identifiable intangible assets and goodwill, contingent consideration, warrant liabilities, stock compensation expense, revenue recognition, restructuring and other charges, excess and obsolete inventory reserves, and deferred tax asset valuation allowances.

Cash and Cash Equivalents and Restricted Cash

The Company considers all highly liquid investments with original maturities of 90 days or less at the time of purchase to be cash equivalents.

Restricted cash at December 31, 2018 includes $590,000 in cash accounts held as collateral primarily under the terms of an office operating lease, credit cards and automobile leases. Restricted cash at December 31, 2017 includes $6.0 million in a money market account, held in connection with the Company’s notes payable (see Note 13) and $389,000 in cash accounts held as collateral primarily under the terms of an office operating lease, credit cards and automobile leases.

Short-term Investments

Short-term investments are considered to be “held-to-maturity” and are carried at amortized cost using the effective interest method. As of December 31, 2018, short-term investments consisted of $51.8 million in U.S. government securities, all of which mature in less than a year. There were no investments as of December 31, 2017.

The Company reassesses the appropriateness of the classification of its investments at the end of each reporting period. The Company has determined that its debt securities should be classified as held-to-maturity as of December 31, 2018. This classification was based upon management’s determination that it has the positive intent and ability to hold the securities until their maturity dates, as the investments mature within 6 months and the underlying cash invested in these securities is not required prior to the investments maturity. Due to the short-term maturities of these instruments, the amortized cost approximates the related fair values, which are based on level 1 inputs as defined in Note 5. As of December 31, 2018, the gross holding gains and losses were immaterial.

The Company reviews its short-term investments for other-than-temporary impairment if the cost exceeds the fair value. No such impairment was recorded as of December 31, 2018.

Concentrations and Credit Risk

The Company’s principal financial instruments subject to potential concentration of credit risk are cash and cash equivalents, including amounts held in money market accounts and short-term investments. The Company places cash deposits with a federally insured financial institution. The Company maintains its cash at banks and financial institutions it considers to be of high credit quality; however, the Company’s cash deposits may at times exceed the FDIC insured limit. Balances in excess of federally insured limitations may not be insured. The Company’s short-term investments consist of U.S. government securities. The Company has not experienced losses on these accounts, and management believes that the Company is not exposed to significant risks on such accounts.

The Company’s accounts receivable are derived from net revenue to customers located throughout the world. The Company evaluates its customers’ financial condition and, generally, requires no collateral from its customers. The Company provides reserves for potential credit losses but has not experienced significant losses to date. The Company had five customers who constituted 89% of the Company’s net accounts receivable at December 31, 2018. The Company had one customer who constituted 88% of the Company’s net accounts receivable at December 31, 2017. The Company had twelve customers who accounted for 89% of sales in 2018, four customers who accounted for 93% of sales in 2017 and one customer who accounted for 100% of sales in 2016.

Accounts Receivable

Accounts receivable are recorded at net realizable value, which includes an allowance for estimated uncollectable accounts. The allowance for uncollectible accounts was determined based on historical collection experience.

Inventories

Inventories are stated at the lower of cost (determined on a first-in, first-out basis) or net realizable value. Inventory costs include direct materials, direct labor, and normal manufacturing overhead. The Company records reserves, when necessary, to reduce the carrying value of inventory to its net realizable value. Management considers forecast demand in relation to the inventory on hand, competitiveness of product offerings, market conditions and product life cycles when determining excess and obsolescence and net realizable value adjustments. At the point of loss recognition, a new, lower-cost basis for that inventory is established, and any subsequent improvements in facts and circumstances do not result in the restoration or increase in that newly established cost basis.

Identifiable Intangible Assets and Goodwill

Identifiable intangible assets are recorded at cost, or when acquired as part of a business acquisition, at estimated fair value. Certain intangible assets are amortized over 5 to 10 years. Similar to tangible personal property and equipment, the Company periodically evaluates identifiable intangible assets for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable.

Intellectual property consists of purchased patent rights and developed technology acquired as part of a business acquisition. Amortization of the patent rights is recorded using the straight-line method over the estimated useful life of the patents of 10 years. Amortization of the developed technology is recorded using the straight-line method over the estimated useful life of 5 to 7 years. This method approximates the period over which the Company expects to receive the benefit from these assets. See Note 17 for additional information related to the write-off of purchased patents in connection with the restructuring plan executed in May 2016. No impairment existed at December 31, 2018 or 2017.

Indefinite-lived intangible assets, such as goodwill, are not amortized. The Company tests the carrying amounts of goodwill for recoverability on an annual basis at December 31 or when events or changes in circumstances indicate evidence a potential impairment exists, using a fair value based test. The Company continues to operate in one segment, which is considered to be the sole reporting unit and therefore, goodwill is tested for impairment at the enterprise level. See Note 10 for additional information related to goodwill impairment recorded during the second quarter of 2016. No impairment existed at December 31, 2018 or 2017.

In-Process Research and Development

In-process research and development (“IPR&D”) assets represent the fair value assigned to technologies that were acquired, which at the time of acquisition have not reached technological feasibility and have no alternative future use. IPR&D assets are considered to be indefinite-lived until the completion or abandonment of the associated research and development projects. During the period that the IPR&D assets are considered indefinite-lived, they are tested for impairment on an annual basis, or more frequently if the Company becomes aware of any events occurring or changes in circumstances that indicate that the fair value of the IPR&D assets are less than their carrying amounts. If and when development is complete, which generally occurs upon regulatory approval, and the Company is able to commercialize products associated with the IPR&D assets, these assets are then deemed definite-lived and are amortized based on their estimated useful lives at that point in time. If development is terminated or abandoned, the Company may have a full or partial impairment charge related to the IPR&D assets, calculated as the excess of carrying value of the IPR&D assets over fair value.

The IPR&D for the Senhance System was acquired on September 21, 2015. On October 13, 2017, upon regulatory approval and the ability to commercialize the products associated with the IPR&D assets, the assets were deemed definite-lived, reclassified to intellectual property and are now amortized based on their estimated useful lives.

The IPR&D from MST was acquired on October 31, 2018.

Property and Equipment

Property and equipment consists primarily of machinery, manufacturing equipment, demonstration equipment, computer equipment, furniture, and leasehold improvements, which are recorded at cost.

Depreciation is recorded using the straight-line method over the estimated useful lives of the assets as follows:

Machinery, manufacturing and demonstration equipment		3-5 years
Computer equipment		3 years
Furniture		5 years
Leasehold improvements		Lesser of lease term or 3 to 10 years

Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation and amortization are removed from the accounts and any resulting gain or loss is credited or charged to operations. Repairs and maintenance costs are expensed as incurred.

Impairment of Long-Lived Assets

The Company reviews its long-lived assets for possible impairment whenever events or changes in circumstances indicate that the carrying amount of the assets may not be fully recoverable. To determine the recoverability of its long-lived assets, the Company evaluates the probability that future estimated undiscounted net cash flows will be less than the carrying amount of the assets. If such estimated cash flows are less than the carrying amount of the long-lived assets, then such assets are written down to their fair value. The Company’s estimates of anticipated cash flows and the remaining estimated useful lives of long-lived assets could be reduced in the future, resulting in a reduction to the carrying amount of long-lived assets.

Contingent Consideration

Contingent consideration is recorded as a liability and is the estimate of the fair value of potential milestone payments related to business acquisitions. Contingent consideration is measured at fair value using a discounted cash flow model utilizing significant unobservable inputs including the probability of achieving each of the potential milestones and an estimated discount rate associated with the risks of the expected cash flows attributable to the various milestones. Significant increases or decreases in any of the probabilities of success or changes in expected timelines for achievement of any of these milestones would result in a significantly higher or lower fair value of these milestones, respectively, and commensurate changes to the associated liability. The contingent consideration is revalued at each reporting period and changes in fair value are recognized in the consolidated statements of operations and comprehensive loss.

Deferred Gain from Sale of SurgiBot Assets

In conjunction with the agreement with GBIL in relation to the transfer of the SurgiBot System assets, the Company received $7.5 million in December 2017. This amount was included in deferred gain from sale of SurgiBot assets in the consolidated balance sheet pending transfer of the assets and was recognized in gain from sale of SurgiBot assets in the consolidated statement of operations and comprehensive loss for the year ended December 31, 2018.

Warrant Liabilities

The Company’s Series A Warrants and Series B Warrants (see Note 16) are measured at fair value using a simulation model which takes into account, as of the valuation date, factors including the current exercise price, the expected life of the warrant, the current price of the underlying stock, its expected volatility, holding cost and the risk-free interest rate for the term of the warrant (see Note 5). The warrant liability is revalued at each reporting period and changes in fair value are recognized in the consolidated statements of operations and comprehensive loss. The selection of the appropriate valuation model and the inputs and assumptions that are required to determine the valuation requires significant judgment and requires management to make estimates and assumptions that affect the reported amount of the related liability and reported amounts of the change in fair value. Actual results could differ from those estimates, and changes in these estimates are recorded when known. As the warrant liability is required to be measured at fair value at each reporting date, it is reasonably possible that these estimates and assumptions could change in the near term.

Translation of Foreign Currencies

The functional currency of the Company’s operational foreign subsidiaries is Euros. The assets and liabilities of the Company’s foreign subsidiaries are translated into U.S. dollars at exchange rates in effect at the balance sheet date. Income and expense items are translated at the average exchange rates prevailing during the period. The cumulative translation effect for a subsidiary using a functional currency other than the U.S. dollar is included in accumulated other comprehensive income or loss as a separate component of stockholders’ equity.

The Company’s intercompany accounts are denominated in the functional currency of the foreign subsidiary. Gains and losses resulting from the remeasurement of intercompany receivables that the Company considers to be of a long-term investment nature are recorded as a cumulative translation adjustment in accumulated other comprehensive income or loss as a separate component of stockholders’ equity, while gains and losses resulting from the remeasurement of intercompany receivables from a foreign subsidiary for which the Company anticipates settlement in the foreseeable future are recorded in the consolidated statements of operations and comprehensive loss. The net gains and losses included in net loss in the consolidated statements of operations and comprehensive loss for the years ended December 31, 2018, 2017, and 2016 were not significant.

Business Acquisitions

Business acquisitions are accounted for using the acquisition method of accounting in accordance with Accounting Standards Codification (“ASC”) 805, “Business Combinations.” ASC 805 requires, among other things, that assets acquired and liabilities assumed be recognized at their fair values, as determined in accordance with ASC 820, “Fair Value Measurements,” as of the acquisition date. For certain assets and liabilities, book value approximates fair value. In addition, ASC 805 establishes that consideration transferred be measured at the closing date of the acquisition at the then-current market price. Under ASC 805, acquisition related costs (i.e., advisory, legal, valuation and other professional fees) and certain acquisition-related restructuring charges impacting the target company are expensed in the period in which the costs are incurred. The application of the acquisition method of accounting requires the Company to make estimates and assumptions related to the estimated fair values of net assets acquired.

Significant judgments are used during this process, particularly with respect to intangible assets. Generally, intangible assets are amortized over their estimated useful lives. Goodwill and other indefinite-lived intangibles are not amortized, but are annually assessed for impairment. Therefore, the purchase price allocation to intangible assets and goodwill has a significant impact on future operating results.

Risk and Uncertainties

The Company is subject to a number of risks similar to other similarly-sized companies in the medical device industry. These risks include, without limitation, the historical lack of profitability; the Company’s ability to raise additional capital; its ability to successfully develop, clinically test and commercialize its products; the timing and outcome of the regulatory review process for its products; changes in the health care and regulatory environments of the United States, Italy, other countries in the European Union, and other countries in which the Company intends to operate; its ability to attract and retain key management, marketing and scientific personnel; competition from new entrants; its ability to successfully prepare, file, prosecute, maintain, defend and enforce patent claims and other intellectual property rights; its ability to successfully transition from a research and development company to a marketing, sales and distribution concern; competition in the market for robotic surgical devices; and its ability to identify and pursue development of additional products.

Revenue Recognition

The Company adopted ASC Topic 606, Revenue from Contracts with Customers (the “New Revenue Standard”), on January 1, 2018. The Company’s revenue consists of product revenue resulting from the sale of systems, system components, instruments and accessories, and service revenue. The Company accounts for a contract with a customer when there is a legally enforceable contract between the Company and the customer, the rights of the parties are identified, the contract has commercial substance, and collectability of the contract consideration is probable. The Company's revenues are measured based on consideration specified in the contract with each customer, net of any sales incentives and taxes collected from customers that are remitted to government authorities.

The Company's system sale arrangements generally contain multiple products and services. For these bundled sale arrangements, the Company accounts for individual products and services as separate performance obligations if they are distinct, which is if a product or service is separately identifiable from other items in the bundled package, and if a customer can benefit from it on its own or with other resources that are readily available to the customer. The Company’s system sale arrangements include a combination of the following performance obligations: system(s), system components, instruments, accessories, and system service. The Company’s system sale arrangements generally include a five-year period of service. The first year of service is generally free and included in the system sale arrangement and the remaining four years are generally included at a stated service price. The Company considers the service terms in the arrangements that are legally enforceable to be performance obligations. Other than service, the Company generally satisfies all of the performance obligations up-front. System components, system accessories, instruments, accessories, and service are also sold on a standalone basis.

The Company recognizes revenues as the performance obligations are satisfied by transferring control of the product or service to a customer. The Company generally recognizes revenue for the performance obligations as follows:

•

System sales. For systems and system components sold directly to end customers, revenue is recognized when the Company transfers control to the customer, which is generally at the point when acceptance occurs that indicates customer acknowledgment of delivery or installation, depending on the terms of the arrangement. For systems sold through distributors, for which distributors are responsible for installation, revenue is recognized generally at the time of shipment. The Company’s system arrangements generally do not provide a right of return. The systems are generally covered by a one-year warranty. Warranty costs were not material for the periods presented.

•

Instruments and accessories. Revenue from sales of instruments and accessories is recognized when control is transferred to the customers, which generally occurs at the time of shipment, but also occurs at the time of delivery depending on the customer arrangement. Accessory products include sterile drapes used to help ensure a sterile field during surgery, vision products such as replacement endoscopes, camera heads, light guides, and other items that facilitate use of the Senhance System.

•

Service. Service revenue is recognized ratably over the term of the service period as the customers benefit from the service throughout the service period. Revenue related to services performed on a time-and-materials basis is recognized when performed.

For multiple-element arrangements, revenue is allocated to each performance obligation based on its relative standalone selling price. Standalone selling prices are based on observable prices at which the Company separately sells the products or services. Due to limited sales to date, standalone selling prices are not directly observable. The Company estimates the standalone selling price using the market assessment approach considering market conditions and entity-specific factors including, but not limited to, features and functionality of the products and services, geographies, type of customer, and market conditions. The Company regularly reviews standalone selling prices and updates these estimates if necessary.

The following table presents revenue disaggregated by type and geography:

	Year Ended
	December 31,
	2018		2017		2016
	(in thousands)
U.S.
Systems	$	2,556	$	865	$	—
Instruments and accessories		967		390		—
Services		255		—		—
Total U.S. revenue		3,778		1,255		—

Outside of U.S. ("OUS")
Systems		16,193		4,198		1,445
Instruments and accessories		3,341		1,080		—
Services		790		578		74
Total OUS revenue		20,324		5,856		1,519

Total
Systems		18,749		5,063		1,445
Instruments and accessories		4,308		1,470		—
Services		1,045		578		74
Total revenue	$	24,102	$	7,111	$	1,519

The Company recognizes sales by geographic area based on the country in which the customer is based.

Transaction price allocated to remaining performance obligations relates to amounts allocated to products and services for which the revenue has not yet been recognized. A significant portion of this amount relates to service obligations performed under the Company's system sales contracts that will be invoiced and recognized as revenue in future periods. Transaction price allocated to remaining performance obligations was approximately $5.6 million as of December 31, 2018.

The Company invoices its customers based on the billing schedules in its sales arrangements. Contract assets for the periods presented primarily represent the difference between the revenue that was recognized based on the relative selling price of the related performance obligations and the contractual billing terms in the arrangements. Contract assets are included in accounts receivable and totaled $0.2 million and $0.1 million as of December 31, 2018 and 2017, respectively. Deferred revenue for the periods presented was primarily related to service obligations, for which the service fees are billed up-front, generally annually. The associated deferred revenue is generally recognized ratably over the service period. The Company did not have any significant impairment losses on its contract assets for the periods presented. Revenue recognized for the years ended December 31, 2018 and 2017, that was included in the deferred revenue balance at the beginning of each reporting period was $0.4 million and $0.3 million, respectively.

In connection with assets recognized from the costs to obtain a contract with a customer, the Company determined that the sales incentive programs for its sales team do not meet the requirements to be capitalized as the Company does not expect to generate future economic benefits from the related revenue from the initial sales transaction.

Cost of Revenue

Cost of revenue consists of contract manufacturing, materials, labor and manufacturing overhead incurred internally to produce the products. Shipping and handling costs incurred by the Company are included in cost of revenue.

Research and Development Costs

Research and development expenses primarily consist of engineering, product development and regulatory expenses, incurred in the design, development, testing and enhancement of our products. Research and development costs are expensed as incurred.

Reversal of Transfer Fee Accrual

In connection with the Senhance acquisition, the Company recorded an accrual of $3.0 million in the 2015 third quarter for the potential assessment of additional transfer fees that could be assessed during a three year period. In September 2018, the Company determined that the accrual was no longer required and reversed the accrual.

Stock-Based Compensation

The Company follows ASC 718 “Stock Compensation” and ASC 505-50 “Equity-Based Payments to Non-employees”, which provide guidance in accounting for share-based awards exchanged for services rendered and requires companies to expense the estimated fair value of these awards over the requisite service period. For awards granted to non-employees, the Company determines the fair value of the stock-based compensation awards granted as either the fair value of the consideration received or the fair value of the equity instruments issued, whichever is more reliably measurable. If the fair value of the equity instruments issued is used, it is measured using the stock price and other measurement assumptions as of the earlier of either (1) the date at which a commitment for performance by the counterparty to earn the equity instruments is reached, or (2) the date at which the counterparty’s performance is complete.

The Company recognizes compensation expense for stock-based awards based on estimated fair values on the date of grant for awards granted to employees. The Company uses the Black-Scholes-Merton option pricing model to determine the fair value of stock options. The fair value of restricted stock units is determined by the market price of the Company’s common stock on the date of grant. The expense associated with stock-based compensation is recognized on a straight-line basis over the requisite service period of each award.

The Company records as expense the fair value of stock-based compensation awards, including stock options and restricted stock units. Compensation expense for stock-based compensation was approximately $9,039,000, $7,078,000 and $5,033,000 for the years ended December 31, 2018, 2017 and 2016, respectively.

Income Taxes

The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets or liabilities for the temporary differences between financial reporting and tax basis of the Company’s assets and liabilities, and for tax carryforwards at enacted statutory rates in effect for the years in which the asset or liability is expected to be realized. The effect on deferred taxes of a change in tax rates is recognized in income during the period that includes the enactment date. In addition, valuation allowances are established when necessary to reduce deferred tax assets and liabilities to the amounts expected to be realized.

On December 22, 2017, the Tax Cuts and Jobs Act (“Tax Legislation”) was enacted into law, which reduced the U.S. federal corporate income tax rate to 21% for tax years beginning after December 31, 2017. As a result of the newly enacted tax rate, the Company adjusted its U.S. deferred tax assets as of December 31, 2017, by applying the new 21% rate, which resulted in a decrease to the deferred tax assets and a corresponding decrease to the valuation allowance of approximately $36.1 million.

The Tax Legislation also implements a territorial tax system. Under the territorial tax system, in general, the Company's foreign earnings will no longer be subject to tax in the U.S. As part of transition to the territorial tax system the Tax Legislation includes a mandatory deemed repatriation of all undistributed foreign earnings that are subject to a U.S. income tax. The Company has determined that the deemed repatriation applicable to the year ending December 31, 2017 does not result in an additional U.S. income tax liability as it has no undistributed foreign earnings.

The SEC staff issued Staff Accounting Bulletin 118, or SAB 118, which allowed the Company to record provisional amounts related to accounting for the Tax Legislation during the measurement period which is similar to the measurement period used when accounting for business combinations. The measurement period has ended and the Company's accounting related to the Tax Legislation is complete. The Company did not make any measurement-period adjustments related to the provisional items recorded as of December 31, 2017 but will continue to assess the impact of the Tax Legislation on its business and consolidated financial statements as additional guidance or interpretations are released.

The FASB Staff Q&A, Topic 740, No. 5, Accounting for Global Intangible Low-Taxed Income(“GILTI”) , states that an entity can make an accounting policy election to either recognize deferred taxes for temporary basis differences expected to reverse as GILTI in future years or to provide for the tax expense related to GILTI in the year the tax is incurred as a period expense only. The Company has elected to account for GILTI as a period expense in the year the tax is incurred.

Comprehensive Loss

Comprehensive loss is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources.

Segments

The Company operates in one business segment—the research, development and sale of medical device robotics to improve minimally invasive surgery. The Company’s chief operating decision maker (determined to be the Chief Executive Officer) does not manage any part of the Company separately, and the allocation of resources and assessment of performance are based on the Company’s consolidated operating results. Approximately 54% and 60% of the Company’s total consolidated assets are located within the U.S. as of December 31, 2018 and 2017, respectively. The remaining assets are mostly located in Europe and are primarily related to the Company’s facility in Italy, and include goodwill, intellectual property, other current assets, property and equipment, cash, accounts receivable and inventory of $111.0 million and $99.9 million at December 31, 2018 and 2017. Total assets outside of the U.S. excluding goodwill amounted to 34% and 31% of total consolidated assets at December 31, 2018 and 2017, respectively. The Company recognizes sales by geographic area based on the country in which the customer is based. For the years ended December 31, 2018, 2017, and 2016, 16%, 18%, and 0%, respectively, of net revenue were generated in the United States; 78%, 61%, and 100% were generated in Europe; and 6%, 21% and 0% were generated in Asia.

Impact of Recently Issued Accounting Standards

In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement. This ASU eliminates, adds and modifies certain disclosure requirements for fair value measurements as part of its disclosure framework project. The standard is effective for all entities for financial statements issued for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted. The Company is currently assessing this ASU and has not yet determined the impact ASU 2018-13 may have on its consolidated financial statements.

In June 2018, the FASB issued ASU 2018-07, Compensation-Stock Compensation (Topic 718), Improvements to Nonemployee Share-based Payments. This ASU expands the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees. ASU 2018-07 is effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. The new guidance is required to be applied retrospectively with the cumulative effect recognized at the date of initial application. The adoption of this ASU should not have a material impact on the consolidated financial statements.

In July 2017, the FASB issued ASU 2017-11, Earnings Per Share (Topic 260); Distinguishing Liabilities from Equity (Topic 480); Derivatives and Hedging (Topic 815): (Part I) Accounting for Certain Financial Instruments with Down Round Features, (Part II) Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception. The amendments in this update are intended to simplify the accounting for certain equity-linked financial instruments and embedded features with down round features that result in the strike price being reduced on the basis of the pricing of future equity offerings. Under the new guidance, a down round feature will no longer need to be considered when determining whether certain financial instruments or embedded features should be classified as liabilities or equity instruments. That is, a down round feature will no longer preclude equity classification when assessing whether an instrument or embedded feature is indexed to an entity's own stock. In addition, the amendments clarify existing disclosure requirements for equity-classified instruments. These amendments are effective for fiscal years, and interim periods within those years, beginning after December 15, 2018, with early adoption permitted. The adoption of this ASU should not have a material impact on the consolidated financial statements.

In February 2017, the FASB issued ASU No. 2017-05, Other Income — Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20) — Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets. The new standard clarifies the scope of guidance applicable to sales of nonfinancial assets and also provides guidance on accounting for partial sales of such assets. The adoption of this ASU did not have an impact on the consolidated financial statements.

In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230) which addresses changes to reduce the presentation diversity of certain cash receipts and cash payments in the statement of cash flows, including debt prepayment or extinguishment costs, settlement of certain debt instruments, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, and distributions received from equity method investees. The guidance became effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years, with early adoption permitted. An entity that elects early adoption must adopt all of the amendments in the same period. The new standard will be applied retrospectively, but may be applied prospectively if retrospective application would be impracticable. The adoption of this ASU did not have an impact on the consolidated financial statements.

In February 2016, the FASB issued ASU 2016-02, Leases. The new standard establishes a right-of-use (ROU) model that requires a lessee to record a ROU asset and a lease liability on the balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. The new standard is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. A modified retrospective transition approach is required for lessees for capital and operating leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with certain practical expedients available. In July 2018, the FASB issued ASU 2018-10, which provides narrow-scope improvements to the lease standard. We expect to elect the ‘package of practical expedients’, which permits us to forgo reassessment of our prior conclusions about lease identification, lease classification and initial direct costs for leases entered into prior to the effective date. Additionally, we expect to elect the practical expedient to not provide comparative reporting periods; therefore, financial information will not be updated and the disclosures required under the new standard will not be provided for dates and periods before January 1, 2019. We do not expect to elect the ‘use-of-hindsight practical expedient’ or the land easement transition relief, the latter of which is not applicable to our industry. Upon adoption, operating leases will be reported on the statement of financial position as gross-up assets and liabilities. The Company has begun evaluating and planning for adoption and implementation of this ASU, including reviewing all material leases, the ASU practical expedient guidelines and current accounting policy elections, and assessing the overall financial statement impact. We expect this ASU will have a material impact on the Company’s financial position. The impact on the Company’s results of operations is currently being evaluated. The impact of this ASU is non-cash in nature and is not expected to affect the Company’s cash flows.

The Company adopted the New Revenue Standard in the first quarter of fiscal year 2018 using the modified retrospective method resulting in a cumulative catch-up adjustment to opening retained earnings. The Company applied the New Revenue Standard to all contracts and concluded that the timing and measurement of revenue recognition is materially consistent under the New Revenue Standard, except for the future billings related to future service included in its multi-year contracts that should be part of the consideration allocated to all performance obligations under the New Revenue Standard. Under the prior standard, future service billings were considered to be contingent revenue, and therefore, were not included in the consideration allocated. Accordingly, the amount of consideration allocated to the performance obligations identified in the Company’s system arrangements is different under the New Revenue Standard than the amount allocated under the prior standard. In general, this will result in an acceleration of the amount of revenue recognized for system sales with multi-year service contracts. Due to limited sales to date, the Company recorded an $11,000 cumulative catch-up adjustment to retained earnings in the first quarter of fiscal year 2018, offset by reductions in accounts receivable of $4,000 and deferred revenue of $15,000. Under the prior standard, revenue would have been $128,000 lower for the year ended December 31, 2018 than under the New Revenue Standard.

Classification of Certain Items Within the Company’s Form 10-K

Certain reclassifications of prior period amounts have been made within the Company’s Form 10-K filing. Specifically, during the six months ended June 30, 2018, the Company determined that the amount related to the deferred gain on sale of SurgiBot assets as reflected within one line in the operating activities section of the consolidated statement of cash flows for the year ended December 31, 2017 should have been classified as cash flows provided from investing activities. There is no impact to the consolidated statements of operations and comprehensive loss or consolidated balance sheets. The Company evaluated the effect of this misclassification and concluded it was not material to any of its previously issued consolidated financial statements. Upon revision, cash flows from operating activities for the year ended December 31, 2017, decreased by $7.5 million to cash and cash equivalents used in operating activities of $47.3 million and cash flows from investing activities increased by $7.5 million to cash and cash equivalents provided by investing activities of $5.5 million.

Acquisitions

12 Months Ended

Dec. 31, 2018

Business Combinations [Abstract]

Acquisitions

3.	Acquisitions

MST Medical Surgery Technologies Ltd. Acquisition

On September 23, 2018, the Company entered into an Asset Purchase Agreement (the “MST Purchase Agreement”) with MST Medical Surgery Technologies Ltd., an Israeli private company (the “Seller”), and two of the Company’s wholly owned subsidiaries, as purchasers of the assets of the Seller, including the intellectual property assets (collectively, the “Buyers”). The closing of the transactions contemplated by the MST Purchase Agreement occurred on October 31, 2018, pursuant to which the Company acquired the Seller’s assets consisting of intellectual property and tangible assets related to surgical analytics with its core image analytics technology designed to empower and automate the surgical environment, with a focus on medical robotics and computer-assisted surgery. The core technology acquired under the MST Purchase Agreement is a software-based image analytics information platform powered by advanced visualization, scene recognition, artificial intelligence, machine learning and data analytics.

Under the terms of the MST Purchase Agreement, at the closing the Buyers purchased substantially all of the assets of the Seller. The acquisition price consisted of two tranches. At or prior to the closing of the transaction the Buyers paid $5.8 million in cash and the Company issued 3.15 million shares of the Company’s common stock. A second tranche of $6.6 million in additional consideration will be payable in cash, stock or cash and stock, at the discretion of the Company, within one year after the closing date.

In connection with the closing under the MST Purchase Agreement (the “MST Acquisition”), the Company and the Seller entered into a Lock-Up Agreement, dated October 31, 2018, pursuant to which the Seller agreed, subject to certain exceptions, not to sell, transfer or otherwise convey any of the shares of Company common stock (the “Securities Consideration”) for six months following the Closing Date. The Lock-Up Agreement further provides that the Seller may sell, transfer or convey: (i) no more than 50% of the Securities Consideration during the period commencing on the six-month anniversary of the Closing Date and ending on the twelve-month anniversary of the Closing Date; and (ii) no more than 75% of the Securities Consideration during the period commencing on the twelve-month anniversary of the Closing Date and ending on the eighteen-month anniversary of the Closing Date. The restrictions on transfer contained in the Lock-Up Agreement cease to apply to the Securities Consideration following the eighteen-month anniversary of the closing date of the MST Acquisition, or earlier upon certain other conditions. The Lock-Up Agreement further provides that the Seller may not sell, transfer or convey the additional consideration, if such additional consideration is paid in whole or in part through the issuance of shares of the Company’s common stock, until after the six-month anniversary of the issuance of the Company’s common stock as additional consideration, or earlier upon certain other conditions.

In connection with the MST Acquisition closing, the Company also entered into a Registration Rights Agreement, dated as of October 31, 2018, with the Seller, pursuant to which the Company agreed to register the Securities Consideration such that such Securities Consideration is eligible for resale following the end of the lock-up periods described above.

The MST Purchase Agreement contains customary representations and warranties of the parties and the parties have customary indemnification obligations, which are subject to certain limitations described further in the MST Purchase Agreement.

The MST Purchase Agreement was accounted for as a business combination utilizing the methodology prescribed in ASC 805. The purchase price for the acquisition was allocated to the assets acquired and liabilities assumed based on their estimated fair values. The purchase price allocation presented herein is preliminary as the Company is finalizing its compilation and review of certain market data used in the valuation of the intangible assets acquired. The final purchase price allocation will be determined after completion of this analysis to determine the fair value of all assets acquired and liabilities assumed, but in no event later than one year following completion of the MST Acquisition. Accordingly, the final acquisition accounting adjustments could differ materially from the preliminary amounts presented herein. Any increase or decrease in the fair value of the assets acquired and liabilities assumed, as compared to the information shown herein, could also change the portion of purchase price allocated to goodwill, and could impact the operating results of the Company following the acquisition due to differences in purchase price allocation.

The following table summarizes the acquisition date fair value of the consideration (in thousands).

Stock consideration	$	8,300
Cash consideration		5,800
Present value of deferred consideration		5,900
Other consideration		314
Total consideration	$	20,314

The value of the stock consideration was determined based on the fair value of the stock on the closing date, adjusted for a lack of marketability discount related to the Lock-Up Agreement. The value of the deferred consideration was determined based on the present value of the future payment using a market interest rate.

The following table summarizes the estimated fair values of the assets acquired and liabilities assumed on October 31, 2018, the date of acquisition (in thousands):

Property and equipment	$	43
In-process research and development		10,633
Goodwill		9,638
Net assets acquired	$	20,314

The Company allocated $10.6 million of the purchase price to identifiable intangible assets of in-process research and development that met the separability and contractual legal criterion of ASC 805. IPR&D is principally the estimated fair value of the MST technology which had not reached commercial technological feasibility nor had alternative future use at the time of the acquisition and therefore the Company considered IPR&D, with assigned values to be allocated to the IPR&D assets acquired.

Goodwill is calculated as the difference between the acquisition-date fair value of the consideration transferred and the fair values of the assets acquired and liabilities assumed. The goodwill resulting from this acquisition arises largely from synergies expected from combining the intellectual property acquired from MST with the Company’s existing intellectual property as well as acquired employees. The goodwill is not deductible for income tax purposes.

The following unaudited pro forma information presents the combined results of operations for the years ended December 31, 2018 and 2017, as if the Company had completed the MST Acquisition at the beginning of fiscal 2017. The pro forma financial information is provided for comparative purposes only and is not necessarily indicative of what actual results would have been had the acquisition occurred on the date indicated, nor does it give effect to synergies, cost savings, fair market value adjustments, and other changes expected to result from the acquisition. Accordingly, the pro forma financial results do not purport to be indicative of consolidated results of operations as of the date hereof, for any period ended on the date hereof, or for any other future date or period. The pro forma consolidated financial information has been calculated after applying the Company’s accounting policies and includes adjustments for transaction-related costs.

	Year Ended December 31,
	2018			2017
	(In thousands except per share amounts)
	(unaudited)
Revenue	$	24,170		$	7,373
Net loss		(64,365	)		(149,985	)
Net loss per share	$	(0.31	)	$	(0.99	)

Since the acquisition date no revenue and a net loss of $0.4 million associated with MST’s operations are included in the consolidated financial statements.

Senhance Surgical Robotic System

On September 21, 2015, the Company completed the strategic acquisition, through its wholly owned subsidiary TransEnterix International, from Sofar, of all of the assets, employees and contracts related to the advanced robotic system for minimally invasive laparoscopic surgery now known as the Senhance System and changed the name of the acquired company from Vulcanos S.r.l. to TransEnterix Italia S.r.l.

Under the terms of the Purchase Agreement, the consideration consisted of the issuance of 15,543,413 shares of the Company’s common stock (the “Securities Consideration”) and approximately $25.0 million U.S. Dollars and €27.5 million Euro in cash consideration (the “Cash Consideration”). The Securities Consideration was issued in full at the closing of the Senhance Acquisition; the Cash Consideration was or will be paid in four tranches, as follows:

(1) $25.0 million of the Cash Consideration, which was paid at closing.

(2) On December 30, 2016, the Company and Sofar entered into an Amendment to the Purchase Agreement (the “Amendment”) to restructure the terms of the second tranche of the Cash Consideration (the “Second Tranche”). Under the Amendment, the Second Tranche was restructured to be paid through the (A) the issuance of 3,722,685 shares of the Company’s common stock with an aggregate fair market value of €5.0 million and (B) the payment of €5.0 million in cash upon the occurrence of either (i) receipt of clearance from the FDA for the Senhance System; or (ii) the Company having cash on hand of at least $50.0 million, or (iii) successfully completing a financing, raising at least $50.0 million in gross proceeds after September 2015, exclusive of any financing proceeds related to the December 2016 purchase agreement between the Company and Lincoln Park Capital Fund, LLC; with payment of simple interest at a rate of 9.0% per annum beginning on December 31, 2016. The Five Million Euro (€ 5,000,000) cash payment began to accrue simple interest at a rate of 9% per annum beginning on December 31, 2016 and continued to accrue interest until November 15, 2017 when it was paid in full.

(3) The third tranche of the Cash Consideration (the “Third Tranche”) of €15.0 million shall be payable upon achievement of trailing revenues from sales or services contracts of the Senhance System of at least €25.0 million over a calendar quarter.

(4) The fourth tranche of the Cash Consideration of €2.5 million was payable in installments by December 31 of each year as reimbursement for certain debt payments made by Sofar under an existing Sofar loan agreement in such year, with payments beginning as of December 31, 2016. As of December 31, 2018, the Company had paid €2.4 million of the fourth tranche.

The Third Tranche payments will be accelerated in the event that (i) the Company or TransEnterix International is acquired, (ii) the Company significantly reduces or suspends selling efforts of the Senhance System, or (iii) the Company acquires a business that offers alternative products that are directly competitive with the Senhance System.

Under the Purchase Agreement, 10% of the Securities Consideration was being held in escrow to support Sofar’s representations and warranties under the Purchase Agreement. In accordance with a related escrow agreement, the escrowed shares were released in September 2016. The Company, a subsidiary and Sofar also entered into a Security Agreement, which provides that 10% of the membership interests of TransEnterix Italia have a lien placed thereon by and in favor of Sofar to support the Company’s representations and warranties under the Purchase Agreement. The security interest period was twenty-four months after the closing of the Senhance Acquisition and expired on September 21, 2017.

The Purchase Agreement contains customary representations and warranties of the parties and the parties have customary indemnification obligations, which are subject to certain limitations described further in the Purchase Agreement.

The Senhance Acquisition was accounted for as a business combination utilizing the methodology prescribed in ASC 805. The purchase price for the Senhance Acquisition was allocated to the assets acquired and liabilities assumed based on their estimated fair values.

The Senhance Acquisition-date fair value of the consideration is as follows (in thousands, except for per share amounts):

Common shares issued		15,543
Closing price per share	$	2.81
	$	43,677
Cash consideration		25,000
Contingent consideration		23,900
Total consideration	$	92,577

The following table summarizes the estimated fair values of the assets acquired and liabilities assumed on September 21, 2015, the date of acquisition (in thousands):

Accounts receivable	$	78
Inventories		2,800
Current deferred tax asset		526
Other current assets		4,180
Property and equipment		1,384
Intellectual property		48,500
In-process research and development		17,100
Goodwill		38,348
Total assets acquired	$	112,916
Accounts payable and other liabilities		1,915
Long-term deferred tax liabilities		18,424
Net assets acquired	$	92,577

The Company allocated $48.5 million of the purchase price to identifiable intangible assets of intellectual property that met the separability and contractual legal criterion of ASC 805. The intellectual property is being amortized using the straight-line method over 7 years.

IPR&D is principally the estimated fair value of the Senhance System technology which had not reached commercial technological feasibility nor had alternative future use at the time of the acquisition and therefore the Company considered IPR&D, with assigned values to be allocated among the various IPR&D assets acquired.

Goodwill is calculated as the difference between the acquisition-date fair value of the consideration transferred and the fair values of the assets acquired and liabilities assumed. The goodwill resulting from this acquisition arises largely from synergies expected from combining the operations of TransEnterix Italia with the Company’s existing operations. The goodwill is not deductible for income tax purposes.

Cash, Cash Equivalents, and Restricted Cash

12 Months Ended

Dec. 31, 2018

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents [Abstract]

Cash, Cash Equivalents, and Restricted Cash

4.	Cash, Cash Equivalents, and Restricted Cash

Cash, cash equivalents and restricted cash consist of the following:

	December 31,		December 31,
	2018		2017
	(In thousands)
Cash	$	1,485	$	4,039
Money market		19,576		87,178
Total cash and cash equivalents	$	21,061	$	91,217
Restricted cash	$	590	$	6,389
Total	$	21,651	$	97,606

Restricted cash at December 31, 2018 includes $590,000 in cash accounts held as collateral primarily under the terms of an office operating lease, credit card agreement and automobile leases. Restricted cash at December 31, 2017 includes $6.0 million in a money market account, held in connection with the Company’s notes payable and $389,000 in cash accounts held as collateral primarily under the terms of an office operating lease, credit card agreement and automobile leases.

Fair Value

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value

5.	Fair Value

The Company held certain assets and liabilities that are required to be measured at fair value on a recurring basis. These assets and liabilities include cash and cash equivalents, restricted cash, contingent consideration and warrant liabilities. ASC 820-10 (“Fair Value Measurement Disclosure”) requires the valuation using a three-tiered approach, which requires that fair value measurements be classified and disclosed in one of three tiers. These tiers are: Level 1, defined as quoted prices in active markets for identical assets or liabilities; Level 2, defined as valuations based on observable inputs other than those included in Level 1, such as quoted prices for similar assets and liabilities in active markets, or other inputs that are observable or can be corroborated by observable input data; and Level 3, defined as valuations based on unobservable inputs reflecting the Company’s own assumptions, consistent with reasonably available assumptions made by other market participants. The Company did not have any transfers of assets and liabilities between Level 1, Level 2, and Level 3 of the fair value hierarchy during the years ended December 31, 2018 and 2017.

For assets and liabilities recorded at fair value, it is the Company’s policy to maximize the use of observable inputs and minimize the use of unobservable inputs when developing fair value measurements, in accordance with the fair value hierarchy. Fair value measurements for assets and liabilities where there exists limited or no observable market data and therefore, are based primarily upon estimates, are often calculated based on the economic and competitive environment, the characteristics of the asset or liability and other factors. Therefore, the results cannot be determined with precision and may not be realized in an actual sale or immediate settlement of the asset or liability. Additionally, there may be inherent weaknesses in any calculation technique, and changes in the underlying assumptions used, including discount rates and estimates of future cash flows, could significantly affect the results of current or future values. The Company utilizes fair value measurements to record fair value adjustments to certain assets and liabilities and to determine fair value disclosures.

As prescribed by U.S. GAAP, the Company groups assets and liabilities at fair value in three levels, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. An adjustment to the pricing method used within either Level 1 or Level 2 inputs could generate a fair value measurement that effectively falls in a lower level in the hierarchy.

The determination of where an asset or liability falls in the hierarchy requires significant judgment. The Company evaluates its hierarchy disclosures and based on various factors, it is possible that an asset or liability may be classified differently from period to period. However, the Company expects changes in classifications between levels will be rare.

The carrying values of accounts receivable, short-term investments, interest receivable, accounts payable, and certain accrued expenses at December 31, 2018 and 2017, approximate their fair values due to the short-term nature of these items. The Company’s notes payable balance also approximates fair value as of December 31, 2018 and 2017, as the interest rates on the notes payable approximate the rates available to the Company as of these dates.

The following are the major categories of assets measured at fair value on a recurring basis as of December 31, 2018 and 2017, using quoted prices in active markets for identical assets (Level 1); significant other observable inputs (Level 2); and significant unobservable inputs (Level 3):

	December 31, 2018
	(In thousands)
	(unaudited)
Description	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets measured at fair value
Cash and cash equivalents	$	21,061	$	—	$	—	$	21,061
Restricted cash		590		—		—		590
Total Assets measured at fair value	$	21,651	$	—	$	—	$	21,651
Liabilities measured at fair value
Contingent consideration	$	—	$	—	$	10,637	$	10,637
Warrant liabilities		—		—	$	4,636	$	4,636
Total liabilities measured at fair value	$	—	$	—	$	15,273	$	15,273

	December 31, 2017
	(In thousands)
Description	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets measured at fair value
Cash and cash equivalents	$	91,217	$	—	$	—	$	91,217
Restricted cash		6,389		—		—		6,389
Total Assets measured at fair value	$	97,606	$	—	$	—	$	97,606
Liabilities measured at fair value
Contingent consideration	$	—	$	—	$	12,418	$	12,418
Warrant liabilities		—		—		14,090		14,090
Total liabilities measured at fair value	$	—	$	—	$	26,508	$	26,508

The Company’s financial liabilities consisted of contingent consideration potentially payable to Sofar related to the Senhance Acquisition in September 2015 (Note 3). This liability is reported as Level 3 as estimated fair value of the contingent consideration related to the acquisition requires significant management judgment or estimation and is calculated using the income approach, using various revenue and cost assumptions and applying a probability to each outcome. The change in fair value of the contingent consideration of $1.0 million for the year ended December 31, 2018 was primarily due to a change in the estimated discount rates and change in expected timing of achievement of the milestone. The change in fair value of the contingent consideration of $2.0 million for the year ended December 31, 2017 was primarily due to the change in expected timelines for the achievement of milestones, the effect of the passage of time on the fair value measurement and the impact of foreign currency exchange rates. Adjustments associated with the change in fair value of contingent consideration are included in the Company’s consolidated statements of operations and comprehensive loss.

On April 28, 2017, the Company sold 24.9 million units (the “Units”), each consisting of one share of the Company’s Common Stock, a Series A warrant to purchase one share of Common Stock with an exercise price of $1.00 per share (the “Series A Warrants”), and a Series B warrant to purchase 0.75 shares of Common Stock with an exercise price of $1.00 per Unit (the “Series B Warrants,” together with the Series A Warrants, the “Warrants”), at an offering price of $1.00 per Unit. Each Series A Warrant was exercisable at any time beginning on the date of issuance, and from time to time thereafter, through and including the first anniversary of the issuance date, unless terminated earlier as provided in the Series A Warrant. Receipt of 510(k) clearance for the Senhance System on October 13, 2017, triggered the acceleration of the expiration date of the Series A Warrants to October 31, 2017 (see Note 16). Each Series B Warrant may be exercised at any time beginning on the date of issuance and from time to time thereafter through and including the fifth anniversary of the issuance date.

The fair value of the Series A Warrants of $2.5 million at the date of issuance was estimated using the Black-Scholes Merton model which used the following inputs: term of 1 year, risk free rate of 1.07%, no dividends, volatility of 73.14%, and share price of $0.65 per share based on the trading price of the Company’s Common Stock. All Series A Warrants were exercised as of December 31, 2017.

The change in fair value of all outstanding Series B warrants for the years ended December 31, 2018 and 2017 of $14.3 million and $83.7 million, respectively was included in the Company’s consolidated statements of operations and comprehensive loss. The following table presents the inputs and valuation methodologies used for the Company’s fair value of the Series B warrants:

April 28, 2017

Series B

December 31, 2018

December 31, 2017

(date of issuance)

Fair value

$4.6 million

$14.1 million

$6.2 million

Valuation methodology

Monte Carlo

Black-Scholes

Merton

Term

3.32 years

4.33 years

5 years

Risk free rate

2.47%

2.13%

1.81%

Dividends

—

Volatility

87.60%

80.60%

73.14%

Share price

2.26

1.93

0.65

Probability of additional financing

100% in 2019

25% in 2018

and 75% in 2019

Not Applicable

The following table presents quantitative information about the inputs and valuation methodologies used for the Company’s fair value measurements classified in Level 3 with the exception of the warrant liability, which is explained above as of December 31, 2018 and 2017:

Valuation

Methodology

Significant

Unobservable Input

Weighted Average

(range, if

applicable)

Contingent consideration

Probability weighted

income approach

Milestone dates

2019 to 2022

Discount rate

11.5% to 12%

The following table summarizes the change in fair value, as determined by Level 3 inputs, for all assets and liabilities using unobservable Level 3 inputs for the years ended December 31, 2018, 2017 and 2016:

	Fair Value Measurement at Reporting Date (Level 3)
	(In thousands)
	Common stock			Contingent
	warrants			consideration
Balance at December 31, 2015		—			23,500
Payment for contingent consideration		—			(1,182	)
Change in fair value		—			482
Balance at December 31, 2016		—			22,800
Issuance of common stock in exchange for contingent consideration		—			(5,227	)
Issuance of warrants		8,715			—
Payment for contingent consideration		—			(7,181	)
Exercise of warrants		(78,359	)		—
Change in fair value		83,734			2,026
Balance at December 31, 2017		14,090			12,418
Payment for contingent consideration		—			(770	)
Exercise of warrants		(23,774	)		—
Change in fair value		14,320			(1,011	)
Balance at December 31, 2018		4,636		$	10,637
Current portion		—			72
Long-term portion		4,636			10,565
Balance at December 31, 2018	$	4,636		$	10,637

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Accounts Receivable, Net

12 Months Ended

Dec. 31, 2018

Receivables [Abstract]

Accounts Receivable, Net

6.	Accounts Receivable, Net

The following table presents the components of accounts receivable:

	December 31,			December 31,
	2018			2017
	(In thousands)
Gross accounts receivable	$	8,640		$	1,609
Allowance for uncollectible accounts		(80	)		(73	)
Total accounts receivable, net	$	8,560		$	1,536

- Definition

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

+ References + Details

Inventories

12 Months Ended

Dec. 31, 2018

Inventory Disclosure [Abstract]

Inventories

7.	Inventories

The components of inventories are as follows:

	December 31,		December 31,
	2018		2017
	(In thousands)
Finished goods	$	5,439	$	4,432
Raw materials		5,502		6,385
Total inventories	$	10,941	$	10,817

As disclosed in Note 17, the Company executed a restructuring plan in May 2016 and wrote down inventory related to the SurgiBot System. The write down of inventory of $2.6 million is included in the accompanying consolidated statement of operations and comprehensive loss for the year ended December 31, 2016. There were no such write-downs for the year ended December 31, 2018 or 2017.

Other Current Assets

12 Months Ended

Dec. 31, 2018

Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]

Other Current Assets

8.	Other Current Assets

The following table presents the components of other current assets:

	December 31,		December 31,
	2018		2017
	(In thousands)
Advances to vendors	$	7,758	$	6,403
Prepaid expenses		1,438		1,519
Other receivables		9		1,422
Total	$	9,205	$	9,344

Property and Equipment

12 Months Ended

Dec. 31, 2018

Property Plant And Equipment [Abstract]

Property and Equipment

9.	Property and Equipment

Property and equipment consisted of the following:

	December 31,			December 31,
	2018			2017
	(In thousands)
Machinery, manufacturing and demonstration equipment	$	12,320		$	10,866
Computer equipment		2,260			2,187
Furniture		639			598
Leasehold improvements		2,280			2,237
Total property and equipment		17,499			15,888
Accumulated depreciation and amortization		(11,162	)		(9,218	)
Property and equipment, net	$	6,337		$	6,670

As disclosed in Note 17, the Company executed a restructuring plan in May 2016 and disposed of certain long-lived assets, primarily equipment and fixtures related to the SurgiBot System. The disposal of long-lived assets of $1.0 million is included as a component of restructuring and other charges in the accompanying consolidated statement of operations and comprehensive loss for the year ended December 31, 2016. There were no such disposals for the year ended December 31, 2018 or 2017.

Depreciation expense was approximately $2,420,000, $2,486,000 and $1,942,000, for the years ended December 31, 2018, 2017 and 2016, respectively.

Goodwill, In-Process Research and Development and Intellectual Property

12 Months Ended

Dec. 31, 2018

Goodwill And Intangible Assets Disclosure [Abstract]

Goodwill, In-Process Research and Development and Intellectual Property

10.	Goodwill, In-Process Research and Development and Intellectual Property

Goodwill

Goodwill of $93.8 million was recorded in connection with the Merger, as described in Note 1, goodwill of $38.3 million was recorded in connection with the Senhance Acquisition, as described in Note 3, and goodwill of $9.6 million was recorded in connection with the MST Acquisition, as described in Note 3. The carrying value of goodwill and the change in the balance for the years ended December 31, 2018, 2017 and 2016 is as follows:

	Goodwill
	(In thousands)
Balance at December 31, 2015	$	130,869
Foreign currency translation impact		(388	)
Impairment loss		(61,784	)
Balance at December 31, 2016	$	68,697
Foreign currency translation impact		2,671
Balance at December 31, 2017		71,368
Additions		9,638
Foreign currency translation impact		(875	)
Balance at December 31, 2018	$	80,131

Accumulated impairment of goodwill as of December 31, 2018 and 2017 was $61.8 million.

The Company performs an annual impairment test of goodwill at December 31, or more frequently if events or changes in circumstances indicates that the carrying value of the Company’s one reporting unit may not be recoverable. During the second quarter of 2016, the FDA notified the Company that the SurgiBot System did not meet the criteria for substantial equivalency, negatively impacting the Company’s market capitalization, and warranting an interim two-step quantitative impairment test. Prior to adopting ASU 2017-04 as of the beginning of fiscal year 2017, goodwill was tested for impairment using a two-step approach. In the first step, the fair value of the reporting unit was determined and compared to the reporting unit's carrying value, including goodwill. If the fair value of the reporting unit was less than its carrying value, the second step of the goodwill impairment test was performed to measure the amount of impairment, if any. In the second step, the fair value of the reporting unit was allocated to the assets and liabilities of the reporting unit as if it had been acquired in a business combination and the purchase price was equivalent to the fair value of the reporting unit. The excess of the fair value of the reporting unit over the amounts assigned to its assets and liabilities was referred to as the implied fair value of goodwill. The implied fair value of the reporting unit's goodwill was then compared to the actual carrying value of goodwill. If the implied fair value of goodwill was less than the carrying value of goodwill, an impairment loss was recognized for the difference. ASU 2017-04 removes Step 2 of the goodwill impairment test. The Company determined the fair value of the reporting unit using a discounted cash flow analysis derived from the Company’s long-term plans. The fair value of the reporting unit was corroborated using market prices for TransEnterix, Inc. The inputs used to determine the fair values were classified as Level 3 in the fair value hierarchy. Based on the impairment test, the Company recorded goodwill impairment of $61.8 million during the second quarter of 2016. No impairment was recorded as of December 31, 2018 or 2017.

The Company performed a qualitative assessment during the annual impairment review for fiscal 2016 as of December 31, 2016 and concluded that it was not more likely than not that the fair value of the Company’s single reporting unit is less than its carrying amount. Therefore, the two-step goodwill impairment test for the reporting unit was not necessary at December 31, 2016. During the second quarter of 2017, the Company’s stock price experienced a significant decline. The Company performed a Step 1 goodwill impairment test as of the second quarter and determined that no charge to goodwill for impairment was required during the second quarter of 2017. As of December 31, 2017 and 2018, the Company elected to bypass the qualitative assessment and calculated the fair value of the Company’s sole reporting unit, based on the Company’s market capitalization which exceeded the carrying amount. Accordingly, no charge for goodwill impairment was required as of December 31, 2018 or 2017.

In-Process Research and Development

As described in Note 3, on October 31, 2018, the Company acquired the assets from MST and recorded $10.6 million of IPR&D. The estimated fair value of the IPR&D was determined using a probability-weighted income approach, which discounts expected future cash flows to present value. The projected cash flows were based on certain key assumptions, including estimates of future revenue and expenses, taking into account the stage of development of the technology at the acquisition date and the time and resources needed to complete development. The Company used a discount rate of 15% and cash flows that have been probability adjusted to reflect the risks of product integration, which the Company believes are appropriate and representative of market participant assumptions.

As described in Note 3, on September 21, 2015, the Company acquired all of the assets related to the Senhance System and recorded $17.1 million of IPR&D. The estimated fair value of the IPR&D was determined using a probability-weighted income approach, which discounts expected future cash flows to present value. The projected cash flows were based on certain key assumptions, including estimates of future revenue and expenses, taking into account the stage of development of the technology at the acquisition date and the time and resources needed to complete development. The Company used a discount rate of 45% and cash flows that have been probability adjusted to reflect the risks of product commercialization, which the Company believes are appropriate and representative of market participant assumptions.

On October 13, 2017, upon receipt of regulatory clearance to commercialize the products associated with the IPR&D assets in the United States, the assets were deemed definite-lived, transferred to developed technology and are amortized based on their estimated useful lives.

The carrying value of the Company’s IPR&D assets and the change in the balance for the years ended December 31, 2017 and 2018 is as follows:

	In-Process Research and Development
	(In thousands)
Balance at December 31, 2016	$	15,920
Foreign currency translation impact		1,993
Transfer to developed technology		(17,913	)
Balance at December 31, 2017		—
Additions		10,633
Foreign currency translation impact		114
Balance at December 31, 2018	$	10,747

Intellectual Property

In 2009, the Company purchased certain patents from an affiliated company for $5.0 million in cash and concurrently terminated a license agreement related to the patents. The patent expiration dates begin in 2027. In addition, as described in Note 3, on September 21, 2015, the Company acquired all of the developed technology related to the Senhance System and recorded $48.5 million of intellectual property. The estimated fair value of the intellectual property was determined using a probability-weighted income approach, which discounts expected future cash flows to present value. The projected cash flows were based on certain key assumptions, including estimates of future revenue and expenses, taking into account the stage of development of the technology at the acquisition date and the time and resources needed to complete development. The Company used a discount rate of 45% and cash flows that have been probability adjusted to reflect the risks of product commercialization, which the Company believes are appropriate and representative of market participant assumptions.

In November 2016, the Company agreed to enter into a technology and patents purchase agreement with Sofar to acquire from Sofar certain technology and intellectual property rights related to the Senhance Acquisition, and formerly licensed by the Company. The technology and patents were acquired in 2017 at an acquisition price of $400,000.

As disclosed in Note 17, the Company executed a restructuring plan in May 2016 and wrote-off certain intellectual property consisting of patents related to the SurgiBot System. The write-off of intellectual property of $1.6 million is included as a component of restructuring and other charges in the accompanying consolidated statement of operations and comprehensive losses for the year ended December 31, 2016. There were no such write offs for the year ended December 31, 2018 or 2017.

The components of gross intellectual property, accumulated amortization, and net intellectual property as of December 31, 2018 and 2017 are as follows:

	December 31, 2018									December 31, 2017
	(In thousands)									(In thousands)
	Gross Carrying Amount		Accumulated Amortization			Foreign currency translation impact		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Foreign currency translation impact		Net Carrying Amount
Developed technology	$	66,413	$	(30,550	)	$	3,495	$	39,358	$	66,413	$	(19,724	)	$	5,529	$	52,218
Technology and patents purchased		400		(72	)		30		358		400		(30	)		50		420
Total intellectual property	$	66,813	$	(30,622	)	$	3,525	$	39,716	$	66,813	$	(19,754	)	$	5,579	$	52,638

The weighted average remaining useful life of the developed technology and technology and patents purchased was 3.8 years and 8.3 years, respectively as of December 31, 2018.

The estimated future amortization expense of intangible assets as of December 31, 2018 is as follows:

	Years ending December 31,
	(In thousands)
2019	$	10,540
2020		10,538
2021		10,538
2022		7,915
2023		42
Thereafter		143
Total	$	39,716

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

11.	Income Taxes

The components for the income tax benefit are as follows for the years ended December 31 (in thousands):

	2018			2017			2016
Current income taxes
Federal	$	—		$	—		$	—
State		—			—			—
Foreign		—			—			—
Deferred income taxes
Federal		—			—			—
State		—			—			—
Foreign		(3,377	)		(3,300	)		(5,523	)
Total income tax benefit	$	(3,377	)	$	(3,300	)	$	(5,523	)

The United States and foreign components of loss from operations before taxes are as follows for the years ended December 31 (in thousands):

	2018			2017			2016
United States	$	(44,744	)	$	(124,418	)	$	(88,624	)
Foreign		(20,410	)		(23,678	)		(36,879	)
Total loss from operations before taxes	$	(65,154	)	$	(148,096	)	$	(125,503	)

Significant components of the Company’s deferred tax assets consist of the following at December 31 (in thousands):

	2018			2017
Noncurrent deferred tax assets:
Stock-based compensation	$	2,281		$	2,216
Inventory		—			375
Accrued expenses and other		795			637
Research credit carryforward		6,182			5,540
Fixed assets		392			450
Capitalized start-up costs and other intangibles		1,859			2,130
Net operating loss carryforwards		74,566			64,300
		86,075			75,648
Valuation allowance		(81,337	)		(71,520	)
Net noncurrent deferred tax asset		4,738			4,128
Noncurrent deferred tax liabilities
Fixed assets		(686	)		(334	)
Purchase accounting intangibles		(8,772	)		(12,183	)
Net noncurrent deferred tax liability		(9,458	)		(12,517	)
Net deferred tax asset (liability)	$	(4,720	)	$	(8,389	)

At December 31, 2018 and 2017, the Company has provided a full valuation allowance against its net deferred assets in the U.S. Luxembourg, and Swiss tax jurisdiction, since realization of these benefits is not more likely than not. The valuation allowance increased approximately $9.8 million from the prior year. At December 31, 2018, the Company had U.S. federal net operating loss tax carryforwards of approximately $290.9 million. Of this amount, $254.5 million begin to expire in 2027, while the remaining $36.4 million carry forward indefinitely. At December 31, 2018, the Company had U.S. state net operating loss carryforwards of $234.6 million. Of this amount, $231.7 million begin to expire in 2022, while the remaining $2.9 million carry forward indefinitely. At December 31, 2018, the Company had federal research credit carryforwards in the amount of $6.2 million. These carryforwards begin to expire in 2027. The utilization of the federal net operating loss carryforwards and credit carryforwards will depend on the Company’s ability to generate sufficient taxable income prior to the expiration of the carryforwards. In addition, the maximum annual use of net operating loss and research credit carryforwards is limited in certain situations where changes occur in stock ownership.

At December 31, 2018, the Company had foreign operating loss carryforwards in Italy of approximately $19.4 million, which can be carried forward indefinitely; foreign operating loss carryforwards in Luxembourg of approximately $0.2 million, which can be carried forward indefinitely; foreign operating loss carryforwards in Switzerland of approximately $24.1 million, which begin to expire in 2023; and foreign operating loss carryforwards in Japan of approximately $0.8 million, which begin to expire in 2028.

The Company has evaluated its tax positions to consider whether it has any unrecognized tax benefits. As of December 31, 2018, the Company had gross unrecognized tax benefits of approximately $1.4 million. Of the total, none would reduce the Company’s effective tax rate if recognized. The Company does not anticipate a significant change in total unrecognized tax benefits or the Company’s effective tax rate due to the settlement of audits or the expiration of statutes of limitations within the next twelve months. Furthermore, the Company does not expect any cash settlement with the taxing authorities as a result of these unrecognized tax benefits as the Company has sufficient unutilized carryforward attributes to offset the tax impact of these adjustments.

The following is a tabular reconciliation of the Company’s change in gross unrecognized tax positions at December 31 (in thousands):

	2018		2017		2016
Beginning balance	$	1,202	$	1,048	$	862
Gross increases for tax positions related to current periods		161		143		186
Gross increases for tax positions related to prior periods		—		11		—
Ending balance	$	1,363	$	1,202	$	1,048

The Company recognizes interest and penalties related to uncertain tax positions in the provision for income taxes. As of December 31, 2018 and 2017, the Company had no accrued interest or penalties related to uncertain tax positions.

The Company has analyzed its filing positions in all significant federal, state, and foreign jurisdictions where it is required to file income tax returns, as well as open tax years in these jurisdictions. With few exceptions, the Company is no longer subject to United States Federal, state, and local tax examinations by tax authorities for years before 2015, although carryforward attributes that were generated prior to 2015 may still be adjusted upon examination by the taxing authorities if they either have been or will be used in a future period. No income tax returns are currently under examination by taxing authorities.

Taxes computed at the then-current statutory federal income tax rate of 21% are reconciled to the provision for income taxes as follows for the years ended December 31:

	2018						2017						2016
				% of Pretax						% of Pretax						% of Pretax
	Amount			Earnings			Amount			Earnings			Amount			Earnings
United States federal tax at statutory rate	$	(13,682	)		21.0	%	$	(50,352	)		34.0	%	$	(42,671	)		34.0	%
State taxes (net of deferred benefit)		(1,080	)		1.7	%		(4,663	)		3.1	%		(2,487	)		2.0	%
Nondeductible expenses		(1,320	)		2.0	%		466			(0.3	%)		667			(0.5	%)
Change in fair market value of contingent consideration		(256	)		0.4	%		777			(0.5	%)		—			—
Warrant remeasurement and financing costs		3,630			(5.6	%)		32,348			(21.8	%)		—			—
Research & Development credits		(803	)		1.2	%		(712	)		0.5	%		(922	)		0.7	%
Change in unrecognized tax benefits		161			(0.2	%)		142			(0.1	%)		186			(0.1	%)
Foreign tax rate differential		(96	)		0.1	%		3,619			(2.4	%)		3,969			(3.2	%)
Goodwill impairment		—			—			—			—			20,816			(16.6	%)
Change in enacted tax rates and other, net		252			(0.3	%)		35,440			(24.1	%)		(1,069	)		0.8	%
Change in valuation allowance		9,817			(15.1	%)		(20,365	)		13.8	%		15,988			(12.7	%)
Income tax benefit	$	(3,377	)		5.2	%	$	(3,300	)		2.2	%	$	(5,523	)		4.4	%

On December 22, 2017, the Tax Legislation was enacted into law, which reduced the U.S. federal corporate income tax rate to 21% for tax years beginning after December 31, 2017. As a result of the newly enacted tax rate, the Company adjusted its U.S. deferred tax assets as of December 31, 2017, by applying the new 21% rate, which resulted in a decrease to the deferred tax assets and a corresponding decrease to the valuation allowance of approximately $36.1 million.

The Tax Legislation also implements a territorial tax system. Under the territorial tax system, in general, the Company's foreign earnings will no longer be subject to tax in the U.S. As part of transition to the territorial tax system the Tax Legislation includes a mandatory deemed repatriation of all undistributed foreign earnings that are subject to a U.S. income tax. The Company determined that the deemed repatriation applicable to the year ending December 31, 2017 did not result in an additional U.S. income tax liability as it has no undistributed foreign earnings.

The Tax Legislation subjects a U.S. shareholder to tax on global intangible low-taxed income (“GILTI”) earned by certain foreign subsidiaries. The FASB Staff Q&A, Topic 740, No. 5, Accounting for Global Intangible Low-Taxed Income, states that an entity can make an accounting policy election to either recognized deferred taxes for temporary basis differences expected to reverse as GILTI in future years or to provide for the tax expense related to GILTI in the year the tax is incurred as a period expense only. Because the Company was evaluating the provision of GILTI as of December 31, 2017, no GILTI-related deferred amounts were recorded in 2017. The Company has elected to account for GILTI in the year the tax is incurred. The Company does not have a GILTI inclusion in 2018; therefore, no GILTI tax has been recorded for the year ending December 31, 2018.

Accrued Expenses

12 Months Ended

Dec. 31, 2018

Accrued Liabilities Current [Abstract]

Accrued Expenses

12.	Accrued Expenses

The following table presents the components of accrued expenses:

	December 31,		December 31,
	2018		2017
	(In thousands)
Compensation and benefits	$	6,225	$	4,533
Consulting and other vendors		895		1,414
Other		539		504
Royalties		498		41
Legal and professional fees		432		386
Deferred rent		391		595
Taxes and other assessments		383		3,192
Interest		256		309
Total	$	9,619	$	10,974

Notes Payable

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Notes Payable

13.	Notes Payable

On May 23, 2018, the Company and its domestic subsidiaries, as co-borrowers, entered into a Loan and Security Agreement (the “Hercules Loan Agreement”) with several banks and other financial institutions or entities from time to time party to the Loan Agreement (collectively, the “Lender”) and Hercules Capital, Inc., as administrative agent and collateral agent (the “Agent”). Under the Hercules Loan Agreement, the Lender has agreed to make certain term loans to the Company in the aggregate principal amount of up to $40,000,000, with funding of the first $20,000,000 tranche occurring on May 23, 2018 (the “Initial Funding Date”). On October 23, 2018, Hercules funded the second tranche of $10,000,000 under the Hercules Loan Agreement. The Company will be eligible to draw on the third tranche of $10,000,000 upon achievement of designated trailing six month GAAP net revenue from Senhance System sales. The Company is entitled to make interest-only payments until December 1, 2020, and at the end of the interest-only period, the Company will be required to repay the term loans over an eighteen-month period based on an eighteen-month amortization schedule, with a final maturity date of June 1, 2022. The term loans will be required to be repaid if the term loans are accelerated following an event of default.

The term loans bear interest at a rate equal to the greater of (i) 9.55% per annum (the “Fixed Rate”) and (ii) the Fixed Rate plus the prime rate (as reported in The Wall Street Journal) minus 5.00%. Following the draw of the third tranche, the Fixed Rate will be reduced to 9.20% effective on the first interest payment date to occur during the first fiscal quarter following the draw of the third tranche. On the Initial Funding Date, the Company was obligated to pay a facility fee of $400,000, recorded as a debt discount. The Company also incurred other debt issuance costs totaling $1.1 million in conjunction with its entry into the Hercules Loan Agreement. In addition, the Company is permitted to prepay the term loans in full at any time, with a prepayment fee of 3.0% of the outstanding principal amount of the loan in the first year after the Initial Funding Date, 2.0% if the prepayment occurs in the second year after the Initial Funding Date and 1.0% thereafter. Upon prepayment of the term loans in full or repayment of the terms loans at the maturity date or upon acceleration, the Company is required to pay a final fee of 6.95% of the aggregate principal amount of term loans funded. The final payment fee is accreted to interest expense over the life of the term loan and included within notes payable on the consolidated balance sheet.

The Company’s obligations under the Hercules Loan Agreement are guaranteed by all current and future material foreign subsidiaries of the Company and are secured by a security interest in all of the assets of the Company and their current and future domestic subsidiaries and all of the assets of their current and future material foreign subsidiaries, including a security interest in the intellectual property. The Hercules Loan Agreement contains customary representations and covenants that, subject to exceptions, restrict the Company’s and its subsidiaries’ ability to do the following, among other things: declare dividends or redeem or repurchase equity interests; incur additional indebtedness and liens; make loans and investments; engage in mergers, acquisitions, and asset sales; transact with affiliates; undergo a change in control; add or change business locations; and engage in businesses that are not related to its existing business. Under the terms of the Hercules Loan Agreement, the Company is required to maintain cash and/or investment property in accounts which perfect the Agent’s first priority security interest in such accounts in an amount equal to the lesser of (i) (x) 120% of the then-outstanding principal balance of the term loans, including accrued interest and any other fees payable under the agreement to the extent accrued and payable plus (y) an amount equal to the then-outstanding accounts payable of the Company on a consolidated basis that are more than 90 days past due and (ii) 80% of the aggregate cash of the Company and its consolidated subsidiaries. As of December 31, 2018, the Company was in compliance with its debt covenants. The Agent is granted the option to invest up to $2,000,000 in any future equity offering broadly marketed by the Company to investors on the same terms as the offering to other investors.

As of December 31, 2018 future principal payments, under the Hercules Loan Agreement are as follows:

Years ending December 31,
(In thousands)
2019	$	—
2020		1,466
2021		18,527
2022		10,007
Total		30,000
Less: Unamortized discount		(1,063	)
Notes payable, net of debt discount	$	28,937

In connection with its entrance into the Hercules Loan Agreement, the Company repaid its existing loan and security agreement (the “Innovatus Loan Agreement”) with Innovatus Life Sciences Lending Fund I, LP (“Innovatus”). The Company recognized a loss of $1.4 million on the extinguishment of notes payable which is included in interest expense on the consolidated statements of operations and comprehensive loss for the year ended December 31, 2018. The Company paid $680,000 in final payment obligations and $287,000 in prepayment fees under the Innovatus Loan Agreement upon repayment.

Under the Innovatus Loan Agreement, entered into on May 10, 2017, Innovatus agreed to make certain term loans in the aggregate principal amount of up to $17,000,000. Funding of the first $14,000,000 tranche occurred on May 10, 2017.

The Innovatus Loan Agreement allowed for interest-only payments for up to twenty-four months at a fixed rate equal to 11% per annum, of which 2.5% could be paid in-kind and added to the outstanding principal amount of the term loans until the earlier of (i) the first anniversary following the funding date and (ii) the Company’s failure to achieve an Interest-Only Milestone. At the end of the interest-only period, the Company would be required to repay the term loans over a two-year period, based on a twenty-four (24) month amortization schedule, with a final maturity date of May 10, 2021.

In connection with the funding, the Company paid a facility fee of $170,000 on the date of funding of the first tranche and incurred additional debt issuance costs of approximately $1.2 million, recorded as a debt discount. In addition, the Company issued warrants to Innovatus to purchase shares of the Company’s common stock that will expire five (5) years from such issue date. The warrants issued in connection with funding of the first tranche entitle Innovatus to purchase up to 1,244,746 shares of the Company’s common stock at an exercise price of $1.00 per share. The Company estimated the fair value of the warrants to be $300,000. The value of the warrants was classified as equity and recorded as a discount to the loan. The debt discount was amortized as interest expense using the effective interest method over the life of the loan. As of December 31, 2018 and 2017, the unamortized debt discount was $0 and $1.0 million, respectively.

In connection with its entrance into the Innovatus Loan Agreement, the Company repaid its then-existing credit facility with Silicon Valley Bank and Oxford Finance LLC, which loan and security agreement, as subsequently amended and restated is referred to as the “SVB Loan Agreement.” The Company recognized a loss of $308,000 on the extinguishment of notes payable which is included in interest expense on the consolidated statement of operations and comprehensive loss for the year ended December 31, 2017. The Company paid $1.3 million in final payment obligations and $255,000 in facility fees under the SVB Loan Agreement upon repayment.

In connection with the issuance of the notes payable and amendments under the SVB Loan Agreement, the Company incurred approximately $371,000 in debt issuance costs paid to Silicon Valley Bank and Oxford Finance and third parties and $280,000 in debt issuance costs related to issuance of warrants to such Prior Lenders. The unamortized balance of $107,000 as of December 31, 2016, was amortized using the effective interest method, until the debt was extinguished in May 2017. At the time of extinguishment in May 2017, $63,000 of unamortized debt issuance costs were included in the loss on extinguishment of notes payable.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

14.	Stock-Based Compensation

The Company’s stock-based compensation plans include the TransEnterix, Inc. Amended and Restated Incentive Compensation Plan, previously named the TransEnterix, Inc. 2007 Incentive Compensation Plan (the “Plan”), as well as options outstanding under the TransEnterix, Inc. Stock Option Plan (the “2006 Plan”). As part of the Merger, options outstanding, whether vested or unvested, under the 2006 Plan were adjusted by the Exchange Ratio of 1.1533, and assumed by the Company concurrent with the closing of the Merger.

The Plan was initially approved by the majority of the stockholders on November 13, 2007. The Plan was amended on June 19, 2012 to increase the number of shares of common stock available for issuance to 1,000,000 and was amended on October 29, 2013 to (a) increase the number of shares of common stock authorized for issuance under the Plan from 1,000,000 shares of common stock to 4,940,000 shares of common stock, (b) increase the per-person award limitations for options or stock appreciation rights from 200,000 to 1,000,000 shares and for restricted stock, deferred stock, performance shares and/or other stock-based awards from 100,000 to 500,000 shares, and (c) change the name of the Plan to reflect the Merger-related change. The Plan was again amended on May 7, 2015 to (i) increase the number of shares reserved for issuance under the Plan to 11,940,000 shares; (ii) extend the term of the Plan until May 7, 2025; and (iii) make other changes and updates to the Plan and was further amended in October 2015 to add French Sub-Plan amendments applicable to awards made to France-based employees. The Plan was further amended on June 8, 2016 to (a) approve an increase in the number of shares reserved for issuance under the Plan to 18,940,000 shares and (b) establish maximum equity award limits for initial awards and annual awards to non-employee directors. The Plan was subsequently amended as of May 25, 2017, increasing the number of shares of Common Stock authorized under the Plan to 25,940,000. The Plan was again amended on May 24, 2018, increasing the number of shares of Common Stock authorized under the Plan to 40,940,000. The Plan was again amended in October 2018 to add an Israeli Sub-Plan applicable to awards made to Israel-based employees.

The October 2013, May 2015, June 2016, May 2017 and May 2018 amendments were approved by the Board of Directors and stockholders; the French Sub-Plan and Israeli Sub-Plan were approved by the Board of Directors. Under the Plan, which is administered by the Compensation Committee, the Company may grant stock options, stock appreciation rights, restricted stock and/or deferred stock to employees, officers, directors, consultants and vendors. The exercise price of stock options or stock appreciation rights may not be less than the fair market value of the Company’s shares at the date of grant. Additionally, no stock options or stock appreciation rights granted under the Plan may have a term exceeding ten years.

The 2006 Plan was adopted and approved by stockholders in September 2006 and provided for the granting of up to 80,000 stock options to employees, directors, and consultants. Under the 2006 Plan, both employees and non-employees were eligible for such stock options. In 2009, the 2006 Plan was amended to increase the total options pool to 1,110,053. In 2011, the 2006 Plan was amended to increase the total options pool to 3,378,189. The amendments were approved by the Board of Directors and stockholders. The Board of Directors had the authority to administer the plan and determine, among other things, the exercise price, term and dates of the exercise of all options at their grant date. Under the 2006 Plan, options become vested generally over four years, and expire not more than 10 years after the date of grant. As part of the Merger, options outstanding under the 2006 Plan were adjusted by the Conversion Ratio, and remain in existence as options of TransEnterix.

During the years ended December 31, 2018, 2017 and 2016, the Company recognized $9,039,000, $7,078,000 and $5,033,000, respectively, of stock-based compensation expense, including stock options and restricted stock units.

The Company recognizes as expense, the grant-date fair value of stock options and other stock based compensation issued to employees and non-employee directors over the requisite service periods, which are typically the vesting periods. The Company uses the Black-Scholes-Merton model to estimate the fair value of its stock-based payments. The volatility assumption used in the Black-Scholes-Merton model is based on the calculated historical volatility based on an analysis of reported data for a peer group of companies as well as the Company’s historical volatility. The expected term of options granted by the Company has been determined based upon the simplified method, because the Company does not have sufficient historical information regarding its options to derive the expected term. Under this approach, the expected term is the mid-point between the weighted average of vesting period and the contractual term. The risk-free interest rate is based on U.S. Treasury rates whose term is consistent with the expected life of the stock options. The Company has not paid and does not anticipate paying cash dividends on its shares of common stock; therefore, the expected dividend yield is assumed to be zero. The Company estimates forfeitures based on the historical experience of the Company and adjusts the estimated forfeiture rate based upon actual experience.

The fair value of options granted were estimated using the Black-Scholes-Merton option pricing model based on the assumptions in the table below:

	Years ended December 31,
	2018	2017	2016
Expected dividend yield	0%	0%	0%
Expected volatility	73% - 75%	70% - 72%	47%
Risk-free interest rate	2.35% - 3.02%	1.84% - 2.29%	1.13% - 2.09%
Expected life (in years)	5.5 - 6.1	5.5 - 6.3	5.5 - 6.3

The following table summarizes the Company’s stock option activity, including grants to non-employees, for the year ended December 31, 2018:

						Weighted-
						Average
				Weighted-		Remaining
	Number of			Average		Contractual
	Shares			Exercise Price		Term (Years)
Options outstanding at December 31, 2017		15,693,675		$	2.32		7.78
Granted		8,705,617			2.39
Forfeited		(925,495	)		1.59
Cancelled		(192,633	)		2.11
Exercised		(3,381,533	)		2.11
Options outstanding at December 31, 2018		19,899,631		$	2.42		7.82

The following table summarizes information about stock options outstanding at December 31, 2018:

					Weighted
					Average
			Weighted		Remaining
	Number of		Average		Contractual
	Shares		Exercise Price		Term (Years)
Exercisable at December 31, 2018		7,574,932	$	2.72		6.53
Vested or expected to vest at December 31, 2018		18,960,684	$	2.42		7.76

The aggregate intrinsic value of stock options outstanding, exercisable, and vested or expected to vest at December 31, 2018 was approximately $9.2 million, $2.3 million, and $8.7 million, respectively. This amount is before applicable income taxes and represents the closing market price of the Company’s common stock at December 31, 2018 less the exercise price, multiplied by the number of stock options that had an exercise price that is less than the closing market price. This amount represents the amount that would have been received by the optionees had these stock options been exercised on that date.

The total intrinsic value of options exercised during 2018, 2017 and 2016 was approximately $9,313,000, $2,179,000 and $519,000, respectively. Proceeds from options exercised during 2018, 2017, and 2016 were approximately $7,128,000, $438,000, and $166,000, respectively.

The Company granted 8,705,617, 4,746,250 and 5,368,755 options to employees and non-employees during the years ended December 31, 2018, 2017 and 2016, respectively, with a weighted-average grant date fair value of $1.59, $0.82 and $1.30, respectively.

As of December 31, 2018, the Company had future employee stock-based compensation expense of approximately $14,429,000 related to unvested share awards, which is expected to be recognized over an estimated weighted-average period of 2.7 years.

Restricted Stock Units

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Restricted Stock Units

15.	Restricted Stock Units

In 2016, 2017 and 2018, the Company issued Restricted Stock Units (“RSUs”) to certain employees which vest over three years. The RSUs vest on defined vesting dates, subject to the continuous service with the Company at the applicable vesting event. Vesting can be accelerated by upon a change in control under the Plan if the RSUs are not assumed by the successor company, and will be accelerated for certain executive officers under existing employment agreements if any such executive officer has a termination of employment in connection with a change in control event. When vested, the RSUs represent the right to be issued the number of shares of the Company’s common stock that is equal to the number of RSUs granted. The fair value of each RSU is estimated based upon the closing price of the Company’s common stock on the grant date. Share-based compensation expense related to RSUs is recognized over the requisite service period as adjusted for estimated forfeitures.

The following is a summary of the RSU activity for the years ended December 31, 2018, 2017 and 2016:

				Weighted
	Number of			Average
	Restricted			Grant
	Stock Units			Date Fair
	Outstanding			Value
Unvested, December 31, 2015		422,500		$	3.64
Granted		660,331			3.74
Vested		(187,503	)		4.53
Unvested, December 31, 2016		895,328		$	3.53
Granted		3,873,000			0.82
Vested		(337,618	)		3.46
Forfeited		(36,054	)		3.60
Unvested, December 31, 2017		4,394,656		$	1.15
Granted		2,215,151			2.20
Vested		(1,605,997	)		1.34
Forfeited		(36,666	)		1.36
Unvested, December 31, 2018		4,967,144		$	1.56

As of December 31, 2018, 2017 and 2016, the Company recorded approximately $2,947,000, $1,751,000 and $1,463,000, respectively, in compensation expense for the RSUs. As of December 31, 2018, the unrecognized stock-based compensation expense related to unvested RSUs was approximately $4.9 million, which is expected to be recognized over a weighted average period of approximately 1.7 years.

Warrants

12 Months Ended

Dec. 31, 2018

Text Block [Abstract]

Warrants

16.

Warrants

On March 22, 2013, SafeStitch entered into a stock purchase agreement with approximately 17 investors (the “2013 PIPE Investors”) pursuant to which the 2013 PIPE Investors purchased an aggregate of approximately 2,420,000 shares of common stock at a price of $1.25 per share for aggregate consideration of approximately $3.0 million. Included in this private placement was the issuance of warrants to purchase approximately 1,209,600 common shares, representing one warrant for every two common shares purchased, with an exercise price of $1.65 per share and five year expiration. Among the 2013 PIPE Investors purchasing shares were related parties who purchased 1.28 million shares and received 640,000 warrants. There were approximately 1.2 million warrants outstanding that were assumed as of the Merger. During the years ended December 31, 2018 and 2017, 800,000 and 240,000, respectively of these warrants were exercised. During the year ended December 31, 2016, none of these warrants were exercised.

On January 17, 2012, TransEnterix Surgical entered into the original Loan Agreement with the Prior Lenders. Pursuant to such agreement, TransEnterix Surgical issued preferred stock warrants to the Prior Lenders on January 17, 2012 and December 21, 2012, respectively, to purchase shares of TransEnterix Surgical preferred stock. The preferred stock warrants expire 10 years from the issue date. The preferred stock warrants were remeasured immediately prior to the Merger. As of the Merger, the preferred stock warrants converted to common stock warrants, adjusted based on a Merger exchange ratio of 1.1533, and the preferred stock warrant liability was reclassified to additional paid-in capital. These warrants are exercisable for an aggregate of approximately 279,588 shares of common stock, with an exercise price of $1.45 per share. During the year ended December 31, 2013, 139,794 of these warrants were exercised in a cashless transaction for 112,766 shares of common stock. None of these warrants were exercised during the years ended December 31, 2017 or 2016. During the year ended December 31, 2018, 139,794 of these warrants were exercised in a cashless transaction for 104,845 shares of common stock.

On September 26, 2014, the Company entered into an amendment to the SVB Loan Agreement with the Prior Lenders. In connection with the first tranche borrowings under such amendment, the Company issued 38,324 common stock warrants to the Prior Lenders to purchase shares of the Company’s common stock, with an exercise price of $4.015 per share. The warrants expire seven years from their respective issue date. The Company concluded that the warrants are considered equity instruments. The warrants were recognized at the relative fair value on the issuance date as a debt discount and will be amortized using the effective interest method from issuance to the maturity of the term loans. None of these warrants were exercised during the years ended December 31, 2017 or 2016. During the year ended December 31, 2018, 27,880 of these warrants were exercised in a cashless transaction for 8,580 shares of common stock.

On August 14, 2015, in connection with an amendment to the SVB Loan Agreement and first tranche borrowings thereunder, the Company issued 112,903 common stock warrants to the Prior Lenders to purchase shares of the Company’s common stock, with an exercise price of $3.10 per share. The warrants expire seven years from their respective issue date. The Company concluded that the warrants are considered equity instruments. The warrants were recognized at the relative fair value on the issuance date as a debt discount and will be amortized using the effective interest method from issuance to the maturity of the note. None of these warrants were exercised during the years ended December 31, 2017 or 2016. During the year ended December 31, 2018, 67,742 of these warrants were exercised in a cashless transaction for 31,535 shares of common stock.

On April 28, 2017, the Company sold 24.9 million Units, each consisting of one share of Common Stock, a Series A Warrant to purchase one share of Common Stock with an exercise price of $1.00 per share, and a Series B Warrant to purchase 0.75 shares of Common Stock with an exercise price of $1.00 per share at an offering price of $1.00 per Unit. Each Series A Warrant may be exercised at any time beginning on the date of issuance, and from time to time thereafter, through and including the first anniversary of the issuance date, unless terminated earlier as provided in the Series A Warrant. Receipt of 510(k) clearance for the Senhance System on October 13, 2017, triggered the acceleration of the expiration date of the Series A Warrants to October 31, 2017. All of the Series A Warrants were exercised prior to the expiration date.

Each Series B Warrant has an initial exercise price of $1.00 per share and may be exercised at any time beginning on the date of issuance and from time to time thereafter through and including the fifth anniversary of the issuance date.

The exercise prices and the number of shares issuable upon exercise of each of the Series B Warrants are subject to adjustment upon the occurrence of certain events, including, but not limited to, stock splits or dividends, business combinations, sale of assets, similar recapitalization transactions, or other similar transactions. The Series B Warrants are subject to adjustment in the event that the Company issues or is deemed to issue shares of Common Stock for less than the then applicable exercise prices of each of the Series B Warrants. The exercisability of the Series B Warrants may be limited if, upon exercise, the holder or any of its affiliates would beneficially own more than 4.99% of the Common Stock. If, at any time Series B Warrants are outstanding, any fundamental transaction occurs, as described in the Series B Warrants and generally including any consolidation or merger into another corporation, the consummation of a transaction whereby another entity acquires more than 50% of the Company’s outstanding voting stock, or the sale of all or substantially all of its assets, the successor entity must assume in writing all of the obligations to the Series B Warrant holders. Additionally, in the event of a fundamental transaction, each Series B Warrant holder will have the right to require the Company, or its successor, to repurchase the Series B Warrants for an amount of cash equal to the Black-Scholes value of the remaining unexercised portion of such Series B Warrants. During the years ended December 31, 2018 and 2017, 7,052,215 and 8,893,700, respectively, Series B Warrants were exercised.

On May 10, 2017, in connection with the entry into the Innovatus Loan Agreement, the Company issued warrants to Innovatus to purchase shares of the Company’s common stock. The warrants are issued on the funding date of each tranche and will expire five (5) years from such issue date. The warrants issued in connection with funding of the first tranche will entitle Innovatus to purchase up to 1,244,746 shares of the Company’s common stock at an exercise price of $1.00 per share. None of these warrants were exercised as of December 31, 2018.

On September 12, 2017, the Company entered into a service agreement with a third party vendor. In connection with the service agreement, the Company issued 950,000 common stock warrants (“Service Warrants”) to purchase shares of the Company’s common stock, with an exercise price of $1.00 per share. The Service Warrants vest as follow: (a) twenty-five percent (25%) on the date of execution of the services agreement; (b) fifty percent (50%) upon completion of hiring the sales team; and (c) the remaining twenty-five percent (25%) upon achieving cumulative product revenue of $15.0 million. The Service Warrants expire ten years from their issue date. The Company concluded that the Service Warrants are considered equity instruments. The fair value of the Service Warrants on the issuance date was determined using a Black-Scholes Merton model. The initial expense of $0.6 million was recognized during the year ended December 31, 2017. The fair value of the remaining Service Warrants will be updated each reporting period and the expense will be recorded over the service period. During the year ended December 31, 2018 and 2017, 650,000 and none of these warrants were exercised, respectively.

						Weighted
				Weighted		Average
				Average		Remaining		Weighted
	Number of			Exercise		Contractual		Average
	Warrants			Price		Life (in years)		Fair Value
Outstanding at December 31, 2015		1,426,622		$	1.81		3.2	$	1.54
Granted		—			—		—		—
Exercised		—			—		—		—
Outstanding at December 31, 2016		1,426,622		$	1.81		2.2	$	1.54
Granted		45,769,746			1.00		4.8		0.22
Exercised		(34,033,700	)		1.00		—		—
Outstanding at December 31, 2017		13,162,668		$	1.08		4.5	$	0.39
Exercised		(8,737,631	)		1.09		—		—
Expired		(95,600	)		1.65		—		—
Outstanding at December 31, 2018		4,329,437		$	1.03		3.7	$	0.26

The aggregate intrinsic value of the common stock warrants in the above table was $5.3 million, $11.2 million and $0 at December 31, 2018, 2017 and 2016, respectively. The aggregate intrinsic value is before applicable income taxes and is calculated based on the difference between the exercise price of the warrants and the estimated fair market value of the applicable stock as of the respective dates.

Restructuring

12 Months Ended

Dec. 31, 2018

Restructuring And Related Activities [Abstract]

Restructuring

17.	Restructuring

On April 19, 2016, the FDA notified the Company that the SurgiBot System did not meet the criteria for substantial equivalence based on the data submitted in the 510(k) submission. In May 2016, the Company implemented a restructuring plan. Under the restructuring plan, the Company reduced headcount, discontinued efforts on the SurgiBot System, and cancelled certain contracts. The restructuring charges amounted to $5.7 million, of which $2.6 million was included as inventory write down related to restructuring and $3.1 million was included as restructuring and other charges in the consolidated statements of operations and comprehensive loss, during the second quarter of 2016.

The restructuring and other charges of $3.1 million included: (i) $0.5 million to be paid in cash, of which $0.4 million related to employee severance costs and $0.1 million related to cancellation of certain contracts; and (ii) $2.6 million for other non-cash charges, of which $1.0 million related to the disposal of long-lived assets for the abandonment of certain equipment and tooling directly relating to the SurgiBot System and $1.6 million related to the write-off of intellectual property for certain patents also relating to the SurgiBot System. There were no future payments under the restructuring plan as of December 31, 2018 or 2017.

Purchase Agreement, Controlled Equity Offering and Public Offering of Common Stock

12 Months Ended

Dec. 31, 2018

Purchase Agreement Controlled Equity Offering And Public Offering Of Common Stock [Abstract]

Purchase Agreement, Controlled Equity Offering and Public Offering of Common Stock

18.	Purchase Agreement, Controlled Equity Offering and Public Offering of Common Stock

On December 28, 2018, the Company entered into an At-the-Market Equity Offering Sales Agreement (the “2018 Sales Agreement”) with Stifel, as sales agent, pursuant to which the Company can sell through Stifel, from time to time, up to $75.0 million in shares of common stock in an at-the-market offering. The Company pays Stifel a commission of approximately 3% of the aggregate gross proceeds received from all sales of common stock under the 2018 Sales Agreement. Unless otherwise terminated earlier, the 2018 Sales Agreement continues until all shares available under the Sales Agreement have been sold or termination of the 2018 Sales Agreement by the Company or by Stifel. As of December 31, 2018, there were no sales of common stock under the 2018 Sales Agreement.

On April 28, 2017, the Company sold 24.9 million units, each consisting of one share of the Company’s common stock, a Series A warrant to purchase one share of common stock, and a Series B warrant to purchase 0.75 shares of common stock, at a public offering price of $1.00 per unit for aggregate gross proceeds of $24.9 million in an underwritten firm commitment public offering. Net proceeds after issuance costs were $23.2 million, assuming no exercise of the warrants. The closing of the public offering occurred on May 3, 2017.

On December 16, 2016, the Company entered into a purchase agreement (the “LPC Purchase Agreement”) with Lincoln Park Capital Fund, LLC, (“Lincoln Park”), pursuant to which the Company had the right to sell to Lincoln Park up to an aggregate of $25.0 million in shares of the Company’s common stock, (the “Common Stock”), subject to certain limitations and conditions set forth in the LPC Purchase Agreement. The Company issued to Lincoln Park 345,421 shares of Common Stock as commitment shares in consideration for the LPC Purchase Agreement through April 27, 2017. Sales under the LPC Purchase Agreement for the year ended December 31, 2016 were 300,000 shares, with gross proceeds of $412,500 and net proceeds of $392,500. Sales under the LPC Purchase Agreement for the year ended December 31, 2017 were 3,972,741 shares, with gross and net proceeds of $5,304,000. Effective April 27, 2017, the Company terminated the LPC Purchase Agreement. The LPC Purchase Agreement provided the Company with an election to terminate the Purchase Agreement for any reason or for no reason by delivering a notice to Lincoln Park, and the Company did not incur any early termination penalties in connection with the termination of the LPC Purchase Agreement.

On February 20, 2015, the Company entered into a Controlled Equity Offering SM Sales Agreement (the “2015 Sales Agreement”) with Cantor Fitzgerald & Co. (“Cantor”), as sales agent, pursuant to which the Company sold through Cantor, from time to time, up to $25.0 million in shares of common stock in an at-the-market offering. The Company paid Cantor a commission of approximately 3% of the aggregate gross proceeds received from all sales of common stock under the 2015 Sales Agreement.

On February 9, 2016, the Company entered into a Controlled Equity Offering SM Sales Agreement (the “2016 Sales Agreement”) with Cantor, as sales agent, pursuant to which the Company can sell through Cantor, from time to time, up to $43.6 million in shares of common stock in an at-the-market offering. The Company paid Cantor a commission of approximately 3% of the aggregate gross proceeds received from all sales of common stock under the 2016 Sales Agreement.

On August 31, 2017, the Company entered into an At-the-Market Equity Offering Sales Agreement (the “2017 Sales Agreement”) with Stifel, Nicolaus & Company, Incorporated (“Stifel”), as sales agent, pursuant to which the Company sold through Stifel, up to $50.0 million in shares of common stock in an at-the-market offering. The Company paid Stifel a commission of approximately 3% of the aggregate gross proceeds received from all sales of common stock under the 2017 Sales Agreement.

The amounts offered and sold under the 2015 Sales Agreement, 2016 Sales Agreement and the 2017 Sales Agreement are as set forth below (in thousands, except per share amounts):

	2017 Sales Agreement		2016 Sales Agreement		2015 Sales Agreement
	Year Ended December 31, 2017		Year Ended December 31, 2016		Year Ended December 31, 2016		Year Ended December 31, 2015
Total shares of common stock sold		15,998.5		8,763.4		5,710.2		2,014.3
Average price per share	$	3.13	$	4.70	$	3.23	$	3.25
Gross proceeds	$	50,000	$	41,156	$	18,454	$	6,546
Commissions earned by Cantor	$	1,500	$	1,235	$	553	$	197
Other issuance costs	$	97	$	185	$	—	$	259

Basic and Diluted Net Loss per Share

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Basic and Diluted Net Loss per Share

19.	Basic and Diluted Net Loss per Share

Basic net loss per common share is computed by dividing net loss attributable to common stockholders by the weighted average number of common shares outstanding during the period. Diluted net loss per common share is computed giving effect to all dilutive potential common shares that were outstanding during the period. Diluted potential common shares consist of incremental shares issuable upon exercise of stock options, warrants and restricted stock units. In computing diluted net loss per share for the years ended December 31, 2018, 2017, and 2016, no adjustment has been made to the weighted average outstanding common shares as the assumed exercise of outstanding options, warrants and restricted stock units would be anti-dilutive.

Potential common shares not included in calculating diluted net loss per share are as follows:

	December 31,
	2018		2017		2016
Stock options		19,899,631		15,693,675		12,488,551
Stock warrants		4,329,437		13,162,668		1,426,622
Nonvested restricted stock units		4,967,144		4,394,656		895,328
Total		29,196,212		33,250,999		14,810,501

Related Person Transactions

12 Months Ended

Dec. 31, 2018

Related Person Transactions

20.	Related Person Transactions

A member of the Company’s Board of Directors is an executive officer of Synecor, LLC. Various research and development services were purchased by the Company from Synecor, LLC and its wholly owned subsidiary Synchrony Labs LLC pursuant to arms’ length terms approved by the Audit Committee and totaled approximately $24,000, $0 and $5,000 for the years ended December 31, 2018, 2017 and 2016, respectively.

On September 18, 2015, TransEnterix Italia entered into a services agreement for receipt of administrative services from Sofar and payment of rent to Sofar, a stockholder that owned approximately 8.9% and 9.7% of the Company’s common stock at December 31, 2018 and 2017, respectively. Expenses under this agreement were approximately $0, $55,000 and $232,000 for the years ended December 31, 2018, 2017 and 2016, respectively. The services agreement terminated in 2017.

As discussed in Note 3, in September 2015, the Company completed the Senhance Acquisition using a combination of cash, stock and potential post-acquisition milestone payments. On December 30, 2016, the Company entered into an Amendment to the Senhance Acquisition purchase agreement with Sofar to restructure the terms of the Second Tranche of the Cash Consideration. Under the Amendment, the Second Tranche was restructured to reduce the contingent cash consideration by €5.0 million in exchange for the issuance of 3,722,685 shares of the Company’s common stock with an aggregate fair market value of €5.0 million. On January 4, 2017, the Company issued to Sofar 3,722,685 shares of the common stock with a fair value of €5.0 million. The price per share was $1.404 and was calculated based on the average of the closing prices of the Company’s common stock on ten consecutive trading days ending one day before the execution of the Amendment.

In March 2018, TransEnterix Europe entered into a Service Supply Agreement with 1Med S.A. for certain regulatory consulting services. Andrea Biffi, a current member of the Company’s Board of Directors, owns a non-controlling interest in 1Med S.A. Expenses under the Service Supply Agreement were approximately $71,000 for the year ended December 31, 2018.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

21.	Commitments and Contingencies

Contingent Consideration

As discussed in Note 3, in September 2015, the Company completed the Senhance Acquisition using a combination of cash, stock and potential post-acquisition milestone payments. These milestone payments may be payable in the future, depending on the achievement of certain regulatory and commercial milestones. On December 30, 2016, the Company entered into an Amendment to restructure the terms of the Second Tranche of the Cash Consideration. Under the Amendment, the Second Tranche was restructured to reduce the contingent cash consideration by €5.0 million in exchange for the issuance of 3,722,685 shares of the Company’s common stock with an aggregate fair market value of €5.0 million. As of December 31, 2018, the fair value of the contingent consideration was $10.6 million.

Legal Proceedings

When determining the estimated probable loss or range of losses, significant judgment is required to be exercised in order to estimate the amount and timing of the loss to be recorded. Estimating an amount or range of possible losses resulting from litigation proceedings is inherently difficult and requires an extensive degree of judgment, particularly where the matters involve indeterminate claims for monetary damages, are in the early stages of the proceedings, and are subject to appeal. In addition, because most legal proceedings are resolved over extended periods of time, potential losses are subject to change due to, among other things, new developments, changes in legal strategy, the outcome of intermediate procedural and substantive rulings and other parties’ settlement posture and their evaluation of the strength or weakness of their case against the Company. For these reasons, the Company is currently unable to predict the ultimate timing or outcome of, or reasonably estimate the possible losses or a range of possible losses resulting from, the matters described above. Based on information currently available, the Company does not believe that any reasonably possible losses arising from currently pending legal matters will be material to the Company’s results of operations or financial condition. However, in light of the inherent uncertainties involved in such matters, an adverse outcome in one or more of these matters could materially and adversely affect the Company’s financial condition, results of operations or cash flows in any particular reporting period.

No liability or related charge was recorded to earnings in the Company’s consolidated financial statements for legal contingencies for the year ended December 31, 2018, as all pending litigation, including two putative derivative claims were dismissed in 2017 with prejudice in the Company's favor.

Operating Leases

On November 2, 2009, TransEnterix Surgical entered into an operating lease for its corporate offices for a period of five years commencing in April 2010. On June 12, 2014, the Company entered into a lease amendment extending the term of the lease for a period of 3 years and 2 months commencing on May 1, 2015 and expiring on June 30, 2018, with an option to renew for an additional three years. On January 8, 2018, the Company entered into a lease amendment extending the term of the lease for a period of eighteen months commencing on July 1, 2018 and expiring on December 31, 2019, with an option to renew for an additional five years. On October 25, 2013, the Company entered into an operating lease for its warehouse for a period of four years and four months commencing in January 2014, with an option to renew for an additional six years. On December 27, 2017, the Company entered into an agreement to terminate this lease effective January 31, 2018. On May 12, 2016, TransEnterix Italia entered into an operating lease for research and development and demonstration facilities for a period of six years commencing in July 2016. Rent expense was approximately $1,186,000, $1,135,000 and $907,000 for the years ended December 31, 2018, 2017 and 2016, respectively. The Company’s approximate future minimum payments for its operating lease obligations that have initial or remaining noncancelable terms in excess of one year are as follow:

	Years ending December 31,
	(In thousands)
2019		929
2020		399
2021		385
2022		175
2023		38
Thereafter		—
Total	$	1,926

License and Supply Agreements

As discussed in Note 3, in September 2015, the Company completed the Senhance Acquisition. As part of this transaction, the Company assumed certain license and supply agreements. Commitments under these agreements amount to approximately $7,301,000 in 2019, $756,000 in 2020, $573,000 in 2021, $573,000 in 2022, $573,000 in 2023 and $1.7 million thereafter until termination in 2027.

The Company has placed orders with various suppliers for the purchase of certain tooling, supplies and contract engineering and research services. Each of these orders has a duration or expected completion within the next twelve months.

Quarterly Results of Operation (Unaudited)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Quarterly Results of Operation (Unaudited)

22.	Quarterly Results of Operation (Unaudited)

The following is a summary of the Company’s unaudited quarterly results of operations for the fiscal years ended December 31, 2018 and 2017 (in thousands, except per share amounts):

	Fiscal Year Ended December 31, 2018
	1st			2nd			3rd			4th			Total
	Quarter			Quarter			Quarter			Quarter			Year
Total revenues	$	4,767		$	6,389		$	5,422		$	7,524		$	24,102
Cost of revenue		2,555			3,732			4,249			5,635			16,171
Gross profit		2,212			2,657			1,173			1,889			7,931
Amortization of intangible assets		2,827			2,743			2,674			2,624			10,868
Change in fair value of contingent consideration		627			812			(1,358	)		(1,092	)		(1,011	)
Acquisition related costs		—			—			345			302			647
Gain from sale of SurgiBot assets, net		(11,996	)		37			44			75			(11,840	)
Other operating expenses		13,911			14,954			14,343			18,205			61,413
Change in fair value of warrant liabilities		(1,829	)		17,507			8,760			(10,118	)		14,320
Reversal of transfer fee accrual		—			—			(2,994	)		—			(2,994	)
Interest income, interest expense and other expense		444			1,735			346			(843	)		1,682
Loss before income taxes		(1,772	)		(35,131	)		(20,987	)		(7,264	)		(65,154	)
Income tax benefit		890			883			781			823			3,377
Net loss	$	(882	)	$	(34,248	)	$	(20,206	)	$	(6,441	)	$	(61,777	)
Net loss per share - basic and diluted	$	0.00		$	(0.17	)	$	(0.10	)	$	(0.03	)	$	(0.30	)

	Fiscal Year Ended December 31, 2017
	1st			2nd			3rd			4th			Total
	Quarter			Quarter			Quarter			Quarter			Year
Total revenues	$	1,946		$	1,584		$	183			3,398		$	7,111
Cost of revenue		1,334			972			921			3,500			6,727
Gross profit (loss)		612			612			(738	)		(102	)		384
Amortization of intangible assets		1,636			1,687			1,821			2,714			7,858
Change in fair value of contingent consideration		1,227			(774	)		773			800			2,026
Issuance costs for warrants		—			627			—			—			627
Other operating expenses		13,627			11,538			12,337			14,298			51,800
Change in fair value of warrant liabilities		—			2,326			22,887			58,521			83,734
Interest income, interest expense and other expense		394			662			695			684			2,435
Loss before income taxes		(16,272	)		(15,454	)		(39,251	)		(77,119	)		(148,096	)
Income tax benefit		858			741			738			963			3,300
Net loss	$	(15,414	)	$	(14,713	)	$	(38,513	)	$	(76,156	)	$	(144,796	)
Net loss per share - basic and diluted	$	(0.13	)	$	(0.11	)	$	(0.26	)	$	(0.40	)	$	(0.97	)

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Basis of Presentation

Use of Estimates

Cash and Cash Equivalents and Restricted Cash

The Company considers all highly liquid investments with original maturities of 90 days or less at the time of purchase to be cash equivalents.

Short-term Investments

The Company reviews its short-term investments for other-than-temporary impairment if the cost exceeds the fair value. No such impairment was recorded as of December 31, 2018.

Concentrations and Credit Risk

Accounts Receivable

Inventories

Identifiable Intangible Assets and Goodwill

In-Process Research and Development

The IPR&D from MST was acquired on October 31, 2018.

Property and Equipment

Property and equipment consists primarily of machinery, manufacturing equipment, demonstration equipment, computer equipment, furniture, and leasehold improvements, which are recorded at cost.

Depreciation is recorded using the straight-line method over the estimated useful lives of the assets as follows:

Machinery, manufacturing and demonstration equipment		3-5 years
Computer equipment		3 years
Furniture		5 years
Leasehold improvements		Lesser of lease term or 3 to 10 years

Impairment of Long-Lived Assets

Contingent Consideration

Deferred Gain from Sale of SurgiBot Assets

Warrant Liabilities

Translation of Foreign Currencies

Business Acquisitions

Risk and Uncertainties

Revenue Recognition

•

The following table presents revenue disaggregated by type and geography:

	Year Ended
	December 31,
	2018		2017		2016
	(in thousands)
U.S.
Systems	$	2,556	$	865	$	—
Instruments and accessories		967		390		—
Services		255		—		—
Total U.S. revenue		3,778		1,255		—

Outside of U.S. ("OUS")
Systems		16,193		4,198		1,445
Instruments and accessories		3,341		1,080		—
Services		790		578		74
Total OUS revenue		20,324		5,856		1,519

Total
Systems		18,749		5,063		1,445
Instruments and accessories		4,308		1,470		—
Services		1,045		578		74
Total revenue	$	24,102	$	7,111	$	1,519

The Company recognizes sales by geographic area based on the country in which the customer is based.

Cost of Revenue

Research and Development Costs

Reversal of Transfer Fee Accrual

Stock-Based Compensation

Income Taxes

Comprehensive Loss

Comprehensive loss is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources.

Segments

Impact of Recently Issued Accounting Standards

Classification of Certain Items Within the Company's Form 10-K

Classification of Certain Items Within the Company’s Form 10-K

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Summary of Estimated Lives of Assets

Depreciation is recorded using the straight-line method over the estimated useful lives of the assets as follows:

Machinery, manufacturing and demonstration equipment		3-5 years
Computer equipment		3 years
Furniture		5 years
Leasehold improvements		Lesser of lease term or 3 to 10 years

Summary of Revenue Disaggregated by Type and Geography

The following table presents revenue disaggregated by type and geography:

	Year Ended
	December 31,
	2018		2017		2016
	(in thousands)
U.S.
Systems	$	2,556	$	865	$	—
Instruments and accessories		967		390		—
Services		255		—		—
Total U.S. revenue		3,778		1,255		—

Outside of U.S. ("OUS")
Systems		16,193		4,198		1,445
Instruments and accessories		3,341		1,080		—
Services		790		578		74
Total OUS revenue		20,324		5,856		1,519

Total
Systems		18,749		5,063		1,445
Instruments and accessories		4,308		1,470		—
Services		1,045		578		74
Total revenue	$	24,102	$	7,111	$	1,519

Acquisitions (Tables)

12 Months Ended

Dec. 31, 2018

Medical Surgery Technologies Ltd. [Member]

Business Acquisition [Line Items]

Summary of Fair Value Consideration

The following table summarizes the acquisition date fair value of the consideration (in thousands).

Stock consideration	$	8,300
Cash consideration		5,800
Present value of deferred consideration		5,900
Other consideration		314
Total consideration	$	20,314

Schedule of Estimated Fair Values of Assets Acquired and Liabilities Assumed

The following table summarizes the estimated fair values of the assets acquired and liabilities assumed on October 31, 2018, the date of acquisition (in thousands):

Property and equipment	$	43
In-process research and development		10,633
Goodwill		9,638
Net assets acquired	$	20,314

Summary of Business Acquisition, Pro Forma Information

The pro forma consolidated financial information has been calculated after applying the Company’s accounting policies and includes adjustments for transaction-related costs.

	Year Ended December 31,
	2018			2017
	(In thousands except per share amounts)
	(unaudited)
Revenue	$	24,170		$	7,373
Net loss		(64,365	)		(149,985	)
Net loss per share	$	(0.31	)	$	(0.99	)

Senhance Surgical Robotic System Acquisition [Member]

Business Acquisition [Line Items]

Summary of Fair Value Consideration

The Senhance Acquisition-date fair value of the consideration is as follows (in thousands, except for per share amounts):

Common shares issued		15,543
Closing price per share	$	2.81
	$	43,677
Cash consideration		25,000
Contingent consideration		23,900
Total consideration	$	92,577

Schedule of Estimated Fair Values of Assets Acquired and Liabilities Assumed

The following table summarizes the estimated fair values of the assets acquired and liabilities assumed on September 21, 2015, the date of acquisition (in thousands):

Accounts receivable	$	78
Inventories		2,800
Current deferred tax asset		526
Other current assets		4,180
Property and equipment		1,384
Intellectual property		48,500
In-process research and development		17,100
Goodwill		38,348
Total assets acquired	$	112,916
Accounts payable and other liabilities		1,915
Long-term deferred tax liabilities		18,424
Net assets acquired	$	92,577

Cash, Cash Equivalents, and Restricted Cash (Tables)

12 Months Ended

Dec. 31, 2018

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents [Abstract]

Summary of Cash, Cash Equivalents and Restricted Cash

Cash, cash equivalents and restricted cash consist of the following:

	December 31,		December 31,
	2018		2017
	(In thousands)
Cash	$	1,485	$	4,039
Money market		19,576		87,178
Total cash and cash equivalents	$	21,061	$	91,217
Restricted cash	$	590	$	6,389
Total	$	21,651	$	97,606

Fair Value (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Measurements Disclosure [Line Items]

Summary of Assets Measured at Fair Value on Recurring Basis

	December 31, 2018
	(In thousands)
	(unaudited)
Description	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets measured at fair value
Cash and cash equivalents	$	21,061	$	—	$	—	$	21,061
Restricted cash		590		—		—		590
Total Assets measured at fair value	$	21,651	$	—	$	—	$	21,651
Liabilities measured at fair value
Contingent consideration	$	—	$	—	$	10,637	$	10,637
Warrant liabilities		—		—	$	4,636	$	4,636
Total liabilities measured at fair value	$	—	$	—	$	15,273	$	15,273

	December 31, 2017
	(In thousands)
Description	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets measured at fair value
Cash and cash equivalents	$	91,217	$	—	$	—	$	91,217
Restricted cash		6,389		—		—		6,389
Total Assets measured at fair value	$	97,606	$	—	$	—	$	97,606
Liabilities measured at fair value
Contingent consideration	$	—	$	—	$	12,418	$	12,418
Warrant liabilities		—		—		14,090		14,090
Total liabilities measured at fair value	$	—	$	—	$	26,508	$	26,508

Change in Fair Value for All Assets and Liabilities Using Unobservable Level 3 Inputs As Determined By Level 3 Inputs

	Fair Value Measurement at Reporting Date (Level 3)
	(In thousands)
	Common stock			Contingent
	warrants			consideration
Balance at December 31, 2015		—			23,500
Payment for contingent consideration		—			(1,182	)
Change in fair value		—			482
Balance at December 31, 2016		—			22,800
Issuance of common stock in exchange for contingent consideration		—			(5,227	)
Issuance of warrants		8,715			—
Payment for contingent consideration		—			(7,181	)
Exercise of warrants		(78,359	)		—
Change in fair value		83,734			2,026
Balance at December 31, 2017		14,090			12,418
Payment for contingent consideration		—			(770	)
Exercise of warrants		(23,774	)		—
Change in fair value		14,320			(1,011	)
Balance at December 31, 2018		4,636		$	10,637
Current portion		—			72
Long-term portion		4,636			10,565
Balance at December 31, 2018	$	4,636		$	10,637

Level 3 [Member]

Fair Value Measurements Disclosure [Line Items]

Quantitative Information about Inputs and Valuation Methodologies Used for Fair Value Measurements Classification

Valuation

Methodology

Significant

Unobservable Input

Weighted Average

(range, if

applicable)

Contingent consideration

Probability weighted

income approach

Milestone dates

2019 to 2022

Discount rate

11.5% to 12%

Series B Warrant [Member]

Fair Value Measurements Disclosure [Line Items]

Quantitative Information about Inputs and Valuation Methodologies Used for Fair Value Measurements Classification

The following table presents the inputs and valuation methodologies used for the Company’s fair value of the Series B warrants

April 28, 2017

Series B

December 31, 2018

December 31, 2017

(date of issuance)

Fair value

$4.6 million

$14.1 million

$6.2 million

Valuation methodology

Monte Carlo

Black-Scholes

Merton

Term

3.32 years

4.33 years

5 years

Risk free rate

2.47%

2.13%

1.81%

Dividends

—

Volatility

87.60%

80.60%

73.14%

Share price

2.26

1.93

0.65

Probability of additional financing

100% in 2019

25% in 2018

and 75% in 2019

Not Applicable

Accounts Receivable, Net (Tables)

12 Months Ended

Dec. 31, 2018

Receivables [Abstract]

Summary of Accounts Receivable

The following table presents the components of accounts receivable:

	December 31,			December 31,
	2018			2017
	(In thousands)
Gross accounts receivable	$	8,640		$	1,609
Allowance for uncollectible accounts		(80	)		(73	)
Total accounts receivable, net	$	8,560		$	1,536

Inventories (Tables)

12 Months Ended

Dec. 31, 2018

Inventory Disclosure [Abstract]

Schedule of Inventory

The components of inventories are as follows:

	December 31,		December 31,
	2018		2017
	(In thousands)
Finished goods	$	5,439	$	4,432
Raw materials		5,502		6,385
Total inventories	$	10,941	$	10,817

Other Current Assets (Tables)

12 Months Ended

Dec. 31, 2018

Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]

Schedule of Other Current Assets

The following table presents the components of other current assets:

	December 31,		December 31,
	2018		2017
	(In thousands)
Advances to vendors	$	7,758	$	6,403
Prepaid expenses		1,438		1,519
Other receivables		9		1,422
Total	$	9,205	$	9,344

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2018

Property Plant And Equipment [Abstract]

Summary of Property and Equipment

Property and equipment consisted of the following:

	December 31,			December 31,
	2018			2017
	(In thousands)
Machinery, manufacturing and demonstration equipment	$	12,320		$	10,866
Computer equipment		2,260			2,187
Furniture		639			598
Leasehold improvements		2,280			2,237
Total property and equipment		17,499			15,888
Accumulated depreciation and amortization		(11,162	)		(9,218	)
Property and equipment, net	$	6,337		$	6,670

Goodwill, In-Process Research and Development and Intellectual Property (Tables)

12 Months Ended

Dec. 31, 2018

Schedule of Goodwill and Intangible Assets [Line Items]

Carrying Value of Goodwill and Change in Balance

The carrying value of goodwill and the change in the balance for the years ended December 31, 2018, 2017 and 2016 is as follows:

	Goodwill
	(In thousands)
Balance at December 31, 2015	$	130,869
Foreign currency translation impact		(388	)
Impairment loss		(61,784	)
Balance at December 31, 2016	$	68,697
Foreign currency translation impact		2,671
Balance at December 31, 2017		71,368
Additions		9,638
Foreign currency translation impact		(875	)
Balance at December 31, 2018	$	80,131

Carrying Value of Company's Intangible Assets and Change in Balance

The components of gross intellectual property, accumulated amortization, and net intellectual property as of December 31, 2018 and 2017 are as follows:

	December 31, 2018									December 31, 2017
	(In thousands)									(In thousands)
	Gross Carrying Amount		Accumulated Amortization			Foreign currency translation impact		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Foreign currency translation impact		Net Carrying Amount
Developed technology	$	66,413	$	(30,550	)	$	3,495	$	39,358	$	66,413	$	(19,724	)	$	5,529	$	52,218
Technology and patents purchased		400		(72	)		30		358		400		(30	)		50		420
Total intellectual property	$	66,813	$	(30,622	)	$	3,525	$	39,716	$	66,813	$	(19,754	)	$	5,579	$	52,638

Summary of Estimated Future Amortization Expense of Intangible Assets

The estimated future amortization expense of intangible assets as of December 31, 2018 is as follows:

	Years ending December 31,
	(In thousands)
2019	$	10,540
2020		10,538
2021		10,538
2022		7,915
2023		42
Thereafter		143
Total	$	39,716

In-Process Research and Development [Member]

Schedule of Goodwill and Intangible Assets [Line Items]

Carrying Value of Company's Intangible Assets and Change in Balance

The carrying value of the Company’s IPR&D assets and the change in the balance for the years ended December 31, 2017 and 2018 is as follows:

	In-Process Research and Development
	(In thousands)
Balance at December 31, 2016	$	15,920
Foreign currency translation impact		1,993
Transfer to developed technology		(17,913	)
Balance at December 31, 2017		—
Additions		10,633
Foreign currency translation impact		114
Balance at December 31, 2018	$	10,747

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Summary of Components of Income Tax Benefit

The components for the income tax benefit are as follows for the years ended December 31 (in thousands):

	2018			2017			2016
Current income taxes
Federal	$	—		$	—		$	—
State		—			—			—
Foreign		—			—			—
Deferred income taxes
Federal		—			—			—
State		—			—			—
Foreign		(3,377	)		(3,300	)		(5,523	)
Total income tax benefit	$	(3,377	)	$	(3,300	)	$	(5,523	)

Schedule of Income (Loss) From Operations Before Taxes

The United States and foreign components of loss from operations before taxes are as follows for the years ended December 31 (in thousands):

	2018			2017			2016
United States	$	(44,744	)	$	(124,418	)	$	(88,624	)
Foreign		(20,410	)		(23,678	)		(36,879	)
Total loss from operations before taxes	$	(65,154	)	$	(148,096	)	$	(125,503	)

Summary of Deferred Tax Assets and Liabilities

Significant components of the Company’s deferred tax assets consist of the following at December 31 (in thousands):

	2018			2017
Noncurrent deferred tax assets:
Stock-based compensation	$	2,281		$	2,216
Inventory		—			375
Accrued expenses and other		795			637
Research credit carryforward		6,182			5,540
Fixed assets		392			450
Capitalized start-up costs and other intangibles		1,859			2,130
Net operating loss carryforwards		74,566			64,300
		86,075			75,648
Valuation allowance		(81,337	)		(71,520	)
Net noncurrent deferred tax asset		4,738			4,128
Noncurrent deferred tax liabilities
Fixed assets		(686	)		(334	)
Purchase accounting intangibles		(8,772	)		(12,183	)
Net noncurrent deferred tax liability		(9,458	)		(12,517	)
Net deferred tax asset (liability)	$	(4,720	)	$	(8,389	)

Summary of Change in Gross Unrecognized Tax Positions

The following is a tabular reconciliation of the Company’s change in gross unrecognized tax positions at December 31 (in thousands):

	2018		2017		2016
Beginning balance	$	1,202	$	1,048	$	862
Gross increases for tax positions related to current periods		161		143		186
Gross increases for tax positions related to prior periods		—		11		—
Ending balance	$	1,363	$	1,202	$	1,048

Summary of Provision for Income Taxes

Taxes computed at the then-current statutory federal income tax rate of 21% are reconciled to the provision for income taxes as follows for the years ended December 31:

	2018						2017						2016
				% of Pretax						% of Pretax						% of Pretax
	Amount			Earnings			Amount			Earnings			Amount			Earnings
United States federal tax at statutory rate	$	(13,682	)		21.0	%	$	(50,352	)		34.0	%	$	(42,671	)		34.0	%
State taxes (net of deferred benefit)		(1,080	)		1.7	%		(4,663	)		3.1	%		(2,487	)		2.0	%
Nondeductible expenses		(1,320	)		2.0	%		466			(0.3	%)		667			(0.5	%)
Change in fair market value of contingent consideration		(256	)		0.4	%		777			(0.5	%)		—			—
Warrant remeasurement and financing costs		3,630			(5.6	%)		32,348			(21.8	%)		—			—
Research & Development credits		(803	)		1.2	%		(712	)		0.5	%		(922	)		0.7	%
Change in unrecognized tax benefits		161			(0.2	%)		142			(0.1	%)		186			(0.1	%)
Foreign tax rate differential		(96	)		0.1	%		3,619			(2.4	%)		3,969			(3.2	%)
Goodwill impairment		—			—			—			—			20,816			(16.6	%)
Change in enacted tax rates and other, net		252			(0.3	%)		35,440			(24.1	%)		(1,069	)		0.8	%
Change in valuation allowance		9,817			(15.1	%)		(20,365	)		13.8	%		15,988			(12.7	%)
Income tax benefit	$	(3,377	)		5.2	%	$	(3,300	)		2.2	%	$	(5,523	)		4.4	%

Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2018

Accrued Liabilities Current [Abstract]

Schedule of Accrued Expenses

The following table presents the components of accrued expenses:

	December 31,		December 31,
	2018		2017
	(In thousands)
Compensation and benefits	$	6,225	$	4,533
Consulting and other vendors		895		1,414
Other		539		504
Royalties		498		41
Legal and professional fees		432		386
Deferred rent		391		595
Taxes and other assessments		383		3,192
Interest		256		309
Total	$	9,619	$	10,974

Notes Payable (Tables)

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Summary of Future Principal Payments under Hercules Loan Agreement

As of December 31, 2018 future principal payments, under the Hercules Loan Agreement are as follows:

Years ending December 31,
(In thousands)
2019	$	—
2020		1,466
2021		18,527
2022		10,007
Total		30,000
Less: Unamortized discount		(1,063	)
Notes payable, net of debt discount	$	28,937

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Share Based Fair Value Assumptions

The fair value of options granted were estimated using the Black-Scholes-Merton option pricing model based on the assumptions in the table below:

	Years ended December 31,
	2018	2017	2016
Expected dividend yield	0%	0%	0%
Expected volatility	73% - 75%	70% - 72%	47%
Risk-free interest rate	2.35% - 3.02%	1.84% - 2.29%	1.13% - 2.09%
Expected life (in years)	5.5 - 6.1	5.5 - 6.3	5.5 - 6.3

Schedule of Stock Option Activity

The following table summarizes the Company’s stock option activity, including grants to non-employees, for the year ended December 31, 2018:

						Weighted-
						Average
				Weighted-		Remaining
	Number of			Average		Contractual
	Shares			Exercise Price		Term (Years)
Options outstanding at December 31, 2017		15,693,675		$	2.32		7.78
Granted		8,705,617			2.39
Forfeited		(925,495	)		1.59
Cancelled		(192,633	)		2.11
Exercised		(3,381,533	)		2.11
Options outstanding at December 31, 2018		19,899,631		$	2.42		7.82

Schedule of Stock Options Outstanding

The following table summarizes information about stock options outstanding at December 31, 2018:

					Weighted
					Average
			Weighted		Remaining
	Number of		Average		Contractual
	Shares		Exercise Price		Term (Years)
Exercisable at December 31, 2018		7,574,932	$	2.72		6.53
Vested or expected to vest at December 31, 2018		18,960,684	$	2.42		7.76

Restricted Stock Units (Tables)

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Summary of Restricted Stock Unit Activity

The following is a summary of the RSU activity for the years ended December 31, 2018, 2017 and 2016:

				Weighted
	Number of			Average
	Restricted			Grant
	Stock Units			Date Fair
	Outstanding			Value
Unvested, December 31, 2015		422,500		$	3.64
Granted		660,331			3.74
Vested		(187,503	)		4.53
Unvested, December 31, 2016		895,328		$	3.53
Granted		3,873,000			0.82
Vested		(337,618	)		3.46
Forfeited		(36,054	)		3.60
Unvested, December 31, 2017		4,394,656		$	1.15
Granted		2,215,151			2.20
Vested		(1,605,997	)		1.34
Forfeited		(36,666	)		1.36
Unvested, December 31, 2018		4,967,144		$	1.56

Warrants (Tables)

12 Months Ended

Dec. 31, 2018

Text Block [Abstract]

Summary of Warrant Activity

Additionally, in the event of a fundamental transaction, each Series B Warrant holder will have the right to require the Company, or its successor, to repurchase the Series B Warrants for an amount of cash equal to the Black-Scholes value of the remaining unexercised portion of such Series B Warrants. During the years ended December 31, 2018 and 2017, 7,052,215 and 8,893,700, respectively, Series B Warrants were exercised.

						Weighted
				Weighted		Average
				Average		Remaining		Weighted
	Number of			Exercise		Contractual		Average
	Warrants			Price		Life (in years)		Fair Value
Outstanding at December 31, 2015		1,426,622		$	1.81		3.2	$	1.54
Granted		—			—		—		—
Exercised		—			—		—		—
Outstanding at December 31, 2016		1,426,622		$	1.81		2.2	$	1.54
Granted		45,769,746			1.00		4.8		0.22
Exercised		(34,033,700	)		1.00		—		—
Outstanding at December 31, 2017		13,162,668		$	1.08		4.5	$	0.39
Exercised		(8,737,631	)		1.09		—		—
Expired		(95,600	)		1.65		—		—
Outstanding at December 31, 2018		4,329,437		$	1.03		3.7	$	0.26

Purchase Agreement, Controlled Equity Offering and Public Offering of Common Stock (Tables)

12 Months Ended

Dec. 31, 2018

Purchase Agreement Controlled Equity Offering And Public Offering Of Common Stock [Abstract]

Schedule of Amounts Offered and Sold under 2015, 2016 and 2017 Sales Agreement

The amounts offered and sold under the 2015 Sales Agreement, 2016 Sales Agreement and the 2017 Sales Agreement are as set forth below (in thousands, except per share amounts):

	2017 Sales Agreement		2016 Sales Agreement		2015 Sales Agreement
	Year Ended December 31, 2017		Year Ended December 31, 2016		Year Ended December 31, 2016		Year Ended December 31, 2015
Total shares of common stock sold		15,998.5		8,763.4		5,710.2		2,014.3
Average price per share	$	3.13	$	4.70	$	3.23	$	3.25
Gross proceeds	$	50,000	$	41,156	$	18,454	$	6,546
Commissions earned by Cantor	$	1,500	$	1,235	$	553	$	197
Other issuance costs	$	97	$	185	$	—	$	259

Basic and Diluted Net Loss per Share (Tables)

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Summary of Potential Common Shares

Potential common shares not included in calculating diluted net loss per share are as follows:

	December 31,
	2018		2017		2016
Stock options		19,899,631		15,693,675		12,488,551
Stock warrants		4,329,437		13,162,668		1,426,622
Nonvested restricted stock units		4,967,144		4,394,656		895,328
Total		29,196,212		33,250,999		14,810,501

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Summary of Future Minimum Payments and Operating Lease Obligations

The Company’s approximate future minimum payments for its operating lease obligations that have initial or remaining noncancelable terms in excess of one year are as follow:

	Years ending December 31,
	(In thousands)
2019		929
2020		399
2021		385
2022		175
2023		38
Thereafter		—
Total	$	1,926

Quarterly Results of Operation (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Summary of Unaudited Quarterly Results of Operations

The following is a summary of the Company’s unaudited quarterly results of operations for the fiscal years ended December 31, 2018 and 2017 (in thousands, except per share amounts):

	Fiscal Year Ended December 31, 2018
	1st			2nd			3rd			4th			Total
	Quarter			Quarter			Quarter			Quarter			Year
Total revenues	$	4,767		$	6,389		$	5,422		$	7,524		$	24,102
Cost of revenue		2,555			3,732			4,249			5,635			16,171
Gross profit		2,212			2,657			1,173			1,889			7,931
Amortization of intangible assets		2,827			2,743			2,674			2,624			10,868
Change in fair value of contingent consideration		627			812			(1,358	)		(1,092	)		(1,011	)
Acquisition related costs		—			—			345			302			647
Gain from sale of SurgiBot assets, net		(11,996	)		37			44			75			(11,840	)
Other operating expenses		13,911			14,954			14,343			18,205			61,413
Change in fair value of warrant liabilities		(1,829	)		17,507			8,760			(10,118	)		14,320
Reversal of transfer fee accrual		—			—			(2,994	)		—			(2,994	)
Interest income, interest expense and other expense		444			1,735			346			(843	)		1,682
Loss before income taxes		(1,772	)		(35,131	)		(20,987	)		(7,264	)		(65,154	)
Income tax benefit		890			883			781			823			3,377
Net loss	$	(882	)	$	(34,248	)	$	(20,206	)	$	(6,441	)	$	(61,777	)
Net loss per share - basic and diluted	$	0.00		$	(0.17	)	$	(0.10	)	$	(0.03	)	$	(0.30	)

	Fiscal Year Ended December 31, 2017
	1st			2nd			3rd			4th			Total
	Quarter			Quarter			Quarter			Quarter			Year
Total revenues	$	1,946		$	1,584		$	183			3,398		$	7,111
Cost of revenue		1,334			972			921			3,500			6,727
Gross profit (loss)		612			612			(738	)		(102	)		384
Amortization of intangible assets		1,636			1,687			1,821			2,714			7,858
Change in fair value of contingent consideration		1,227			(774	)		773			800			2,026
Issuance costs for warrants		—			627			—			—			627
Other operating expenses		13,627			11,538			12,337			14,298			51,800
Change in fair value of warrant liabilities		—			2,326			22,887			58,521			83,734
Interest income, interest expense and other expense		394			662			695			684			2,435
Loss before income taxes		(16,272	)		(15,454	)		(39,251	)		(77,119	)		(148,096	)
Income tax benefit		858			741			738			963			3,300
Net loss	$	(15,414	)	$	(14,713	)	$	(38,513	)	$	(76,156	)	$	(144,796	)
Net loss per share - basic and diluted	$	(0.13	)	$	(0.11	)	$	(0.26	)	$	(0.40	)	$	(0.97	)

Organization and Capitalization - Additional Information (Detail) - USD ($)	1 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 06, 2013
Organization And Capitalization [Line Items]
Common stock, shares authorized	750,000,000	750,000,000
Preferred stock, shares authorized			25,000,000
Preferred stock, par value (in dollars per share)			$ 0.01
Minimum [Member]
Organization And Capitalization [Line Items]
Common stock, shares authorized			225,000,000
Maximum [Member]
Organization And Capitalization [Line Items]
Common stock, shares authorized			750,000,000
China National Scientific and Instruments and Materials Company [Member]
Organization And Capitalization [Line Items]
Proceeds from distribution agreement	$ 15,000,000
Distribution minimum royalties payment	14,000,000
China National Scientific and Instruments and Materials Company [Member] \| Minimum [Member]
Organization And Capitalization [Line Items]
Expected proceeds from distribution agreement	$ 29,000,000

Summary of Significant Accounting Policies - Additional Information (Detail)		3 Months Ended			12 Months Ended
	Sep. 21, 2015	Sep. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2018 USD ($) Segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Accounting Policies [Line Items]
Short-term investments					$ 51,790,000
Impairment charges					0	$ 0
Deferred gain from sale of SurgiBot assets					$ 7,500,000
Period of service sale arrangement					5 years
Period of service sale arrangement at stated service price					4 years
Product warranty					1 year
Revenue, remaining performance obligation					$ 5,600,000
Contract assets included in accounts receivable					200,000	100,000
Revenue recognized, included in deferred revenue					400,000	$ 300,000
Reversal of transfer fee accrual		$ 2,994,000			$ 2,994,000
Statutory income tax rate					21.00%	34.00%	34.00%
Decrease in deferred tax assets due to newly enacted tax rate						$ 36,100,000
Decrease in valuation allowance due to newly enacted tax rate						36,100,000
Number of business segments \| Segment					1
Assets					$ 239,307,000	250,251,000
Cumulative catch-up adjustment to retained earnings					11,000
Reductions in accounts receivable					(7,225,000)	(381,000)	$ (1,041,000)
Cash and cash equivalents used in operating activities					48,493,000	47,295,000	52,386,000
Cash and cash equivalents provided by investing activities					(53,481,000)	5,509,000	(1,361,000)
Restatement Adjustment [Member]
Accounting Policies [Line Items]
Cash and cash equivalents used in operating activities						7,500,000
Cash and cash equivalents provided by investing activities						$ 7,500,000
ASU 2014-09 [Member]
Accounting Policies [Line Items]
Cumulative catch-up adjustment to retained earnings			$ 11,000
Reductions in accounts receivable			4,000
Deferred revenue			$ 15,000
ASU 2014-09 [Member] \| Prior Standard, Revenue [Member]
Accounting Policies [Line Items]
Deferred revenue					$ (128,000)
U.S. [Member]
Accounting Policies [Line Items]
Percentage of total consolidated assets					54.00%	60.00%
International [Member]
Accounting Policies [Line Items]
Percentage of total consolidated assets, excluding goodwill					34.00%	31.00%
Stock Options [Member]
Accounting Policies [Line Items]
Share based compensation, expense recognized					$ 9,039,000	$ 7,078,000	$ 5,033,000
Senhance Surgical Robotic System Acquisition [Member]
Accounting Policies [Line Items]
Amortization period	7 years
Transfer fee accrual term				3 years
Reversal of transfer fee accrual				$ 3,000,000
Senhance Surgical Robotic System Acquisition [Member] \| Europe [Member]
Accounting Policies [Line Items]
Assets					$ 111,000,000	$ 99,900,000
Patents [Member]
Accounting Policies [Line Items]
Amortization period					10 years
Minimum [Member]
Accounting Policies [Line Items]
Amortization period					5 years
Minimum [Member] \| Developed Technology [Member]
Accounting Policies [Line Items]
Amortization period					5 years
Maximum [Member]
Accounting Policies [Line Items]
Amortization period					10 years
Maximum [Member] \| Developed Technology [Member]
Accounting Policies [Line Items]
Amortization period					7 years
Customer Concentration Risk [Member] \| Accounts Receivable [Member] \| Five Customer [Member]
Accounting Policies [Line Items]
Concentration Risk Percentage					89.00%
Customer Concentration Risk [Member] \| Accounts Receivable [Member] \| One Customer [Member]
Accounting Policies [Line Items]
Concentration Risk Percentage						88.00%
Customer Concentration Risk [Member] \| Sales [Member] \| One Customer [Member]
Accounting Policies [Line Items]
Concentration Risk Percentage							100.00%
Customer Concentration Risk [Member] \| Sales [Member] \| Four Customer [Member]
Accounting Policies [Line Items]
Concentration Risk Percentage						93.00%
Customer Concentration Risk [Member] \| Sales [Member] \| Twelve Customer [Member]
Accounting Policies [Line Items]
Concentration Risk Percentage					89.00%
Geographic Concentration Risk [Member] \| Sales [Member] \| U.S. [Member]
Accounting Policies [Line Items]
Concentration Risk Percentage					16.00%	18.00%	0.00%
Geographic Concentration Risk [Member] \| Sales [Member] \| Europe [Member]
Accounting Policies [Line Items]
Concentration Risk Percentage					78.00%	61.00%	100.00%
Geographic Concentration Risk [Member] \| Sales [Member] \| Asia [Member]
Accounting Policies [Line Items]
Concentration Risk Percentage					6.00%	21.00%	0.00%
U.S. Government Securities [Member]
Accounting Policies [Line Items]
Short-term investments					$ 51,800,000	$ 0
Short-term investments, other-than-temporary impairment					0
Held In Cash Collateral Accounts [Member]
Accounting Policies [Line Items]
Restricted cash					$ 590,000	389,000
Held In Cash Money Market Account [Member]
Accounting Policies [Line Items]
Restricted cash						$ 6,000,000

Summary of Significant Accounting Policies - Summary of Estimated Lives of Assets (Detail)	12 Months Ended
	Dec. 31, 2018
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful lives	3 years
Furniture [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful lives	5 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful lives	Lesser of lease term or 3 to 10 years
Minimum [Member] \| Machinery, Manufacturing Equipment and Demonstration Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful lives	3 years
Minimum [Member] \| Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful lives	3 years
Maximum [Member] \| Machinery, Manufacturing Equipment and Demonstration Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful lives	5 years
Maximum [Member] \| Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful lives	10 years

Summary of Significant Accounting Policies - Summary of Revenue Disaggregated by Type and Geography (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation Of Revenue [Line Items]
Total revenue	$ 24,102	$ 7,111	$ 1,519
Systems [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	18,749	5,063	1,445
Instruments and Accessories [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	4,308	1,470
Services [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	1,045	578	74
U.S. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	3,778	1,255
U.S. [Member] \| Systems [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	2,556	865
U.S. [Member] \| Instruments and Accessories [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	967	390
U.S. [Member] \| Services [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	255
Outside of U.S. [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	20,324	5,856	1,519
Outside of U.S. [Member] \| Systems [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	16,193	4,198	1,445
Outside of U.S. [Member] \| Instruments and Accessories [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	3,341	1,080
Outside of U.S. [Member] \| Services [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	$ 790	$ 578	$ 74

Acquisitions - Additional Information (Detail)						3 Months Ended								12 Months Ended
Acquisitions - Additional Information (Detail)	Oct. 31, 2018 USD ($) shares	Jan. 04, 2017 EUR (€)	Dec. 30, 2016 EUR (€) shares	Sep. 21, 2015 USD ($) shares	Sep. 21, 2015 EUR (€) shares	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2018 EUR (€)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 21, 2015 EUR (€)
Business Acquisition [Line Items]
Additional consideration payable in cash, stock or cash and stock														$ 10,637,000		$ 12,418,000
Revenue														24,102,000		7,111,000	$ 1,519,000
Net loss						$ (6,441,000)	$ (20,206,000)	$ (34,248,000)	$ (882,000)	$ (76,156,000)	$ (38,513,000)	$ (14,713,000)	$ (15,414,000)	$ (61,777,000)		$ (144,796,000)	(119,980,000)
Securities consideration held in escrow percentage				10.00%	10.00%
Escrow and security interest period				24 months	24 months
Escrow and security interest expiration date				Sep. 21, 2017	Sep. 21, 2017
Maximum [Member]
Business Acquisition [Line Items]
Amortization period														10 years	10 years
Minimum [Member]
Business Acquisition [Line Items]
Amortization period														5 years	5 years
Medical Surgery Technologies Ltd. [Member]
Business Acquisition [Line Items]
Cash consideration	$ 5,800,000
Acquisition agreement, description	The Lock-Up Agreement further provides that the Seller may sell, transfer or convey: (i) no more than 50% of the Securities Consideration during the period commencing on the six-month anniversary of the Closing Date and ending on the twelve-month anniversary of the Closing Date; and (ii) no more than 75% of the Securities Consideration during the period commencing on the twelve-month anniversary of the Closing Date and ending on the eighteen-month anniversary of the Closing Date. The restrictions on transfer contained in the Lock-Up Agreement cease to apply to the Securities Consideration following the eighteen-month anniversary of the closing date of the MST Acquisition, or earlier upon certain other conditions.
In-process research and development	$ 10,633,000
Revenue														$ 0
Net loss														400,000
Medical Surgery Technologies Ltd. [Member] \| Ending on Twelve Month Anniversary [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Percentage of securities consideration	50.00%
Medical Surgery Technologies Ltd. [Member] \| Ending on Eighteen Month Anniversary [Member] \| Maximum [Member]
Business Acquisition [Line Items]
Percentage of securities consideration	75.00%
Medical Surgery Technologies Ltd. [Member] \| First Tranche [Member]
Business Acquisition [Line Items]
Cash consideration	$ 5,800,000
Common shares issued \| shares	3,150,000
Medical Surgery Technologies Ltd. [Member] \| Second Tranche [Member]
Business Acquisition [Line Items]
Additional consideration payable in cash, stock or cash and stock	$ 6,600,000
Senhance Surgical Robotic System Acquisition [Member]
Business Acquisition [Line Items]
Cash consideration				$ 25,000,000
Common shares issued \| shares				15,543,413	15,543,413
Additional consideration payable in cash, stock or cash and stock				$ 23,900,000										$ 10,600,000
In-process research and development				17,100,000
Intellectual property, net				$ 48,500,000
Amortization period				7 years	7 years
Senhance Surgical Robotic System Acquisition [Member] \| U.S. Dollars [Member]
Business Acquisition [Line Items]
Cash consideration				$ 25,000,000
Senhance Surgical Robotic System Acquisition [Member] \| Euro [Member]
Business Acquisition [Line Items]
Cash consideration \| €					€ 27,500,000
Senhance Surgical Robotic System Acquisition [Member] \| First Tranche [Member]
Business Acquisition [Line Items]
Cash consideration				$ 25,000,000
Senhance Surgical Robotic System Acquisition [Member] \| Second Tranche [Member]
Business Acquisition [Line Items]
Common shares issued \| shares			3,722,685
Additional consideration payable in cash, stock or cash and stock \| €		€ 5,000,000
Aggregate fair market value \| €			€ 5,000,000
Aggregate fair market value payment \| €			€ 5,000,000
Senhance Surgical Robotic System Acquisition [Member] \| Second Tranche [Member] \| Lincoln Park Capital Fund, LLC [Member]
Business Acquisition [Line Items]
Gross proceeds from financing																	$ 50,000,000
Interest rate																	9.00%
Senhance Surgical Robotic System Acquisition [Member] \| Second Tranche [Member] \| Minimum [Member] \| Lincoln Park Capital Fund, LLC [Member]
Business Acquisition [Line Items]
Cash on hand																	$ 50,000,000
Senhance Surgical Robotic System Acquisition [Member] \| Third Tranche [Member]
Business Acquisition [Line Items]
Cash consideration payable \| €																		€ 15,000,000
Senhance Surgical Robotic System Acquisition [Member] \| Third Tranche [Member] \| Minimum [Member]
Business Acquisition [Line Items]
Target revenue to be achieved \| €																		25,000,000
Senhance Surgical Robotic System Acquisition [Member] \| Fourth Tranche [Member]
Business Acquisition [Line Items]
Cash consideration \| €															€ 2,400,000
Cash consideration payable \| €																		€ 2,500,000
TransEnterix Italia [Member]
Business Acquisition [Line Items]
Membership interests percentage under Security agreement				10.00%														10.00%

Acquisitions - Summary of Fair Value Consideration (Detail) - USD ($)			1 Months Ended	12 Months Ended
	Oct. 31, 2018	Sep. 21, 2015	Nov. 30, 2016	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Contingent consideration				$ 10,637,000	$ 12,418,000
Medical Surgery Technologies Ltd. [Member]
Business Acquisition [Line Items]
Stock consideration	$ 8,300,000
Cash consideration	5,800,000
Present value of deferred consideration	5,900,000
Other consideration	314,000
Total consideration	$ 20,314,000
Senhance Surgical Robotic System Acquisition [Member]
Business Acquisition [Line Items]
Common shares issued		15,543,413
Closing price per share		$ 2.81
Stock consideration		$ 43,677,000
Cash consideration		25,000,000
Contingent consideration		23,900,000		$ 10,600,000
Total consideration		$ 92,577,000	$ 400,000

Acquisitions - Schedule of Estimated Fair Values of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Oct. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 21, 2015
Business Acquisition [Line Items]
Goodwill	$ 80,131		$ 71,368	$ 68,697	$ 130,869
Medical Surgery Technologies Ltd. [Member]
Business Acquisition [Line Items]
Property and equipment		$ 43
In-process research and development		10,633
Goodwill	9,600	9,638
Net assets acquired		$ 20,314
Senhance Surgical Robotic System Acquisition [Member]
Business Acquisition [Line Items]
Accounts receivable						$ 78
Inventories						2,800
Current deferred tax asset						526
Other current assets						4,180
Property and equipment						1,384
Intellectual property						48,500
In-process research and development						17,100
Goodwill	$ 38,300					38,348
Total assets acquired						112,916
Accounts payable and other liabilities						1,915
Long-term deferred tax liabilities						18,424
Net assets acquired						$ 92,577

Acquisitions - Summary of Business Acquisition, Pro Forma Information (Detail) - Medical Surgery Technologies Ltd. [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Revenue	$ 24,170	$ 7,373
Net loss	$ (64,365)	$ (149,985)
Net loss per share	$ (0.31)	$ (0.99)

Cash, Cash Equivalents, and Restricted Cash - Summary of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents [Abstract]
Cash	$ 1,485	$ 4,039
Money market	19,576	87,178
Total cash and cash equivalents	21,061	91,217
Restricted cash	590	6,389
Total	$ 21,651	$ 97,606	$ 34,590	$ 38,449

Cash, Cash Equivalents, and Restricted Cash - Additional Information (Detail) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Restricted Cash And Cash Equivalents Items [Line Items]
Restricted cash	$ 590,000	$ 6,389,000
Held In Cash Money Market Account [Member]
Restricted Cash And Cash Equivalents Items [Line Items]
Restricted cash		6,000,000
Held In Cash Collateral Accounts [Member]
Restricted Cash And Cash Equivalents Items [Line Items]
Restricted cash	$ 590,000	$ 389,000

Fair Value - Additional Information (Detail)		3 Months Ended							12 Months Ended
Fair Value - Additional Information (Detail)	Apr. 28, 2017 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) $ / shares	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2018 USD ($) $ / shares	Dec. 31, 2017 USD ($) $ / shares
Fair Value Measurements Disclosure [Line Items]
Transfers of assets between Level 1, Level 2, and Level 3 of the fair value hierarchy \| $		$ 0				$ 0			$ 0	$ 0
Transfers of liabilities between Level 1, Level 2, and Level 3 of the fair value hierarchy \| $		0				0			0	0
Warrants to purchase common shares \| shares	24,900,000
Offering price \| $ / shares	$ 1.00
Change in fair value of warrant liabilities \| $		$ (10,118,000)	$ 8,760,000	$ 17,507,000	$ (1,829,000)	58,521,000	$ 22,887,000	$ 2,326,000	$ 14,320,000	83,734,000
Series A Warrant [Member]
Fair Value Measurements Disclosure [Line Items]
Warrants, exercise price \| $ / shares	$ 1.00
Warrant expiration date	Oct. 31, 2017
Series A Warrant [Member] \| Black-Scholes Merton Model [Member]
Fair Value Measurements Disclosure [Line Items]
Estimated fair value of warrants \| $	$ 2,500,000
Fair value input, share price \| $ / shares	$ 0.65
Series A Warrant [Member] \| Black-Scholes Merton Model [Member] \| Measurement Input, Expected Term [Member]
Fair Value Measurements Disclosure [Line Items]
Fair value input, term	1 year
Series A Warrant [Member] \| Black-Scholes Merton Model [Member] \| Measurement Input, Risk Free Interest Rate [Member]
Fair Value Measurements Disclosure [Line Items]
Fair value input, risk free rate	0.0107
Series A Warrant [Member] \| Black-Scholes Merton Model [Member] \| Measurement Input, Expected Dividend Payment [Member]
Fair Value Measurements Disclosure [Line Items]
Fair value input, risk free rate	0
Series A Warrant [Member] \| Black-Scholes Merton Model [Member] \| Measurement Input, Price Volatility [Member]
Fair Value Measurements Disclosure [Line Items]
Fair value input, risk free rate	0.7314
Series B Warrant [Member]
Fair Value Measurements Disclosure [Line Items]
Warrants, exercise price \| $ / shares	$ 1.00	$ 1.00							$ 1.00
Estimated fair value of warrants \| $	$ 6,200,000	$ 4,600,000				$ 14,100,000			$ 4,600,000	$ 14,100,000
Fair value input, share price \| $ / shares	$ 0.65	$ 2.26				$ 1.93			$ 2.26	$ 1.93
Change in fair value of warrant liabilities \| $									$ 14,300,000	$ 83,700,000
Series B Warrant [Member] \| Measurement Input, Expected Term [Member]
Fair Value Measurements Disclosure [Line Items]
Fair value input, term	5 years	3 years 3 months 25 days				4 years 3 months 29 days			3 years 3 months 25 days	4 years 3 months 29 days
Series B Warrant [Member] \| Measurement Input, Risk Free Interest Rate [Member]
Fair Value Measurements Disclosure [Line Items]
Fair value input, risk free rate	1.81	2.47				2.13			2.47	2.13
Series B Warrant [Member] \| Measurement Input, Price Volatility [Member]
Fair Value Measurements Disclosure [Line Items]
Fair value input, risk free rate	73.14	87.60				80.60			87.60	80.60
Common Stock [Member]
Fair Value Measurements Disclosure [Line Items]
Number of common stock or warrants in each unit \| shares	1
Common Stock [Member] \| Series A Warrant [Member]
Fair Value Measurements Disclosure [Line Items]
Number of common stock or warrants in each unit \| shares	1
Warrants, exercise price \| $ / shares	$ 1.00
Common Stock [Member] \| Series B Warrant [Member]
Fair Value Measurements Disclosure [Line Items]
Number of common stock or warrants in each unit \| shares	0.75
Warrants, exercise price \| $ / shares	$ 1.00
Senhance Surgical Robotic System Acquisition [Member]
Fair Value Measurements Disclosure [Line Items]
Fair value of contingent consideration \| $									$ 1,000,000	$ 2,000,000

Fair Value - Summary of Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Assets measured at fair value
Cash and cash equivalents	$ 21,061	$ 91,217
Restricted cash	590	6,389
Total Assets measured at fair value	21,651	97,606
Liabilities measured at fair value
Contingent consideration	10,637	12,418
Warrant liabilities	4,636	14,090
Total liabilities measured at fair value	15,273	26,508
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets measured at fair value
Cash and cash equivalents	21,061	91,217
Restricted cash	590	6,389
Total Assets measured at fair value	21,651	97,606
Significant Unobservable Inputs (Level 3) [Member]
Liabilities measured at fair value
Contingent consideration	10,637	12,418
Warrant liabilities	4,636	14,090
Total liabilities measured at fair value	$ 15,273	$ 26,508

Fair Value - Quantitative Information about Inputs and Valuation Methodologies Used for Fair Value Measurements Classification (Detail) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares	Dec. 31, 2017 USD ($) $ / shares	Apr. 28, 2017 USD ($) $ / shares
Senhance Surgical Robotic System Acquisition [Member] \| Significant Unobservable Inputs (Level 3) [Member] \| Contingent Consideration [Member] \| Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Milestone dates	2019
Senhance Surgical Robotic System Acquisition [Member] \| Significant Unobservable Inputs (Level 3) [Member] \| Contingent Consideration [Member] \| Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Milestone dates	2022
Measurement Input, Discount Rate [Member] \| Senhance Surgical Robotic System Acquisition [Member] \| Significant Unobservable Inputs (Level 3) [Member] \| Contingent Consideration [Member] \| Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rate	0.115
Measurement Input, Discount Rate [Member] \| Senhance Surgical Robotic System Acquisition [Member] \| Significant Unobservable Inputs (Level 3) [Member] \| Contingent Consideration [Member] \| Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rate	0.12
Series B Warrant [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value \| $	$ 4.6	$ 14.1	$ 6.2
Valuation methodology	trxc:MonteCarloMember	trxc:MonteCarloMember	trxc:BlackScholesMertonMember
Share price \| $ / shares	$ 2.26	$ 1.93	$ 0.65
Probability of additional financing in 2018		25.00%
Probability of additional financing in 2019	100.00%	75.00%
Series B Warrant [Member] \| Measurement Input, Expected Term [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Term	3 years 3 months 25 days	4 years 3 months 29 days	5 years
Series B Warrant [Member] \| Measurement Input, Risk Free Interest Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Risk free rate	2.47	2.13	1.81
Series B Warrant [Member] \| Measurement Input, Price Volatility [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Risk free rate	87.60	80.60	73.14

Fair Value - Change in Fair Value for All Assets and Liabilities Using Unobservable Level 3 Inputs As Determined By Level 3 Inputs (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Common Stock Warrants [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 14,090
Issuance of warrants		$ 8,715
Exercise of warrants	(23,774)	(78,359)
Change in fair value	14,320	83,734
Long-term portion	4,636
Ending balance	4,636	14,090
Contingent Consideration [Member]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	12,418	22,800	$ 23,500
Issuance of common stock in exchange for contingent consideration		(5,227)
Payment for contingent consideration	(770)	(7,181)	(1,182)
Change in fair value	(1,011)	2,026	482
Current portion	72
Long-term portion	10,565
Ending balance	$ 10,637	$ 12,418	$ 22,800

Accounts Receivable, Net - Summary of Accounts Receivable (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Gross accounts receivable	$ 8,640	$ 1,609
Allowance for uncollectible accounts	(80)	(73)
Total accounts receivable, net	$ 8,560	$ 1,536

Inventories - Schedule of Inventory (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Finished goods	$ 5,439	$ 4,432
Raw materials	5,502	6,385
Total inventories	$ 10,941	$ 10,817

Inventories - Additional Information (Detail) - USD ($)	12 Months Ended
Inventories - Additional Information (Detail) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Inventory [Line Items]
Write down of inventory			$ 2,565,000
SurgiBot System [Member]
Inventory [Line Items]
Write down of inventory	$ 0	$ 0	$ 2,600,000

Other Current Assets - Schedule of Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Advances to vendors	$ 7,758	$ 6,403
Prepaid expenses	1,438	1,519
Other receivables	9	1,422
Total	$ 9,205	$ 9,344

Property and Equipment - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 17,499	$ 15,888
Accumulated depreciation and amortization	(11,162)	(9,218)
Property and equipment, net	6,337	6,670
Machinery, Manufacturing and Demonstration Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	12,320	10,866
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	2,260	2,187
Furniture [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	639	598
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 2,280	$ 2,237

Property and Equipment - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Abstract]
Disposal of long-lived assets	$ 0	$ 0	$ 1,000,000
Depreciation	$ 2,420,000	$ 2,486,000	$ 1,942,000

Goodwill, In-Process Research and Development and Intellectual Property - Additional Information (Detail) - USD ($)			1 Months Ended	3 Months Ended		12 Months Ended
	Oct. 31, 2018	Sep. 21, 2015	Nov. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2009
Goodwill And Intangible Assets [Line Items]
Goodwill						$ 80,131,000	$ 71,368,000	$ 68,697,000	$ 130,869,000
Accumulated impairment of goodwill						61,800,000	61,800,000
Goodwill impairment				$ 0	$ 61,800,000	0	0	61,784,000
In-Process Research and Development [Member]
Goodwill And Intangible Assets [Line Items]
Discount rate	15.00%	45.00%
Patents [Member]
Goodwill And Intangible Assets [Line Items]
Patent purchased amount										$ 5,000,000
Patents [Member] \| SurgiBot System [Member]
Goodwill And Intangible Assets [Line Items]
Write-off of intellectual property						0	0	$ 1,600,000
Intellectual Property [Member]
Goodwill And Intangible Assets [Line Items]
Discount rate		45.00%
Patent purchased amount						66,813,000	66,813,000
Technology and Patents Purchased [Member]
Goodwill And Intangible Assets [Line Items]
Patent purchased amount						$ 400,000	400,000
Weighted average remaining useful life						8 years 3 months 18 days
Developed Technology [Member]
Goodwill And Intangible Assets [Line Items]
Patent purchased amount						$ 66,413,000	66,413,000
Weighted average remaining useful life						3 years 9 months 18 days
Safe Stitch Medical Inc [Member]
Goodwill And Intangible Assets [Line Items]
Goodwill						$ 93,800,000
Senhance Surgical Robotic System Acquisition [Member]
Goodwill And Intangible Assets [Line Items]
Goodwill		$ 38,348,000				38,300,000
Intellectual property		48,500,000
Acquisition price		92,577,000	$ 400,000
Senhance Surgical Robotic System Acquisition [Member] \| In-Process Research and Development [Member]
Goodwill And Intangible Assets [Line Items]
In-process research and development		$ 17,100,000
Senhance Surgical Robotic System Acquisition [Member] \| Technology and Patents Purchased [Member]
Goodwill And Intangible Assets [Line Items]
Acquisition price							$ 400,000
Medical Surgery Technologies Ltd. [Member]
Goodwill And Intangible Assets [Line Items]
Goodwill	$ 9,638,000					$ 9,600,000
Acquisition price	20,314,000
Medical Surgery Technologies Ltd. [Member] \| In-Process Research and Development [Member]
Goodwill And Intangible Assets [Line Items]
In-process research and development	$ 10,600

Goodwill, In-Process Research and Development and Intellectual Property - Carrying Value of Goodwill and Change in Balance (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill And Intangible Assets Disclosure [Abstract]
Beginning balance			$ 71,368,000	$ 68,697,000	$ 130,869,000
Additions			9,638,000
Foreign currency translation impact			(875,000)	2,671,000	(388,000)
Impairment loss	$ 0	$ (61,800,000)	0	0	(61,784,000)
Ending balance			$ 80,131,000	$ 71,368,000	$ 68,697,000

Goodwill, In-Process Research and Development and Intellectual Property - Carrying Value of Company's IPR&D Assets and Change in Balance (Detail) - In-Process Research and Development [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Beginning balance		$ 15,920
Additions	$ 10,633
Foreign currency translation impact	114	1,993
Transfer to developed technology		$ (17,913)
Ending balance	$ 10,747

Goodwill, In-Process Research and Development and Intellectual Property - Summary of Gross Intellectual Property, Accumulated Amortization, and Net Intellectual Property (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Developed Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 66,413	$ 66,413
Accumulated Amortization	(30,550)	(19,724)
Foreign currency translation impact	3,495	5,529
Net Carrying Amount	39,358	52,218
Technology and Patents Purchased [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	400	400
Accumulated Amortization	(72)	(30)
Foreign currency translation impact	30	50
Net Carrying Amount	358	420
Intellectual Property [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	66,813	66,813
Accumulated Amortization	(30,622)	(19,754)
Foreign currency translation impact	3,525	5,579
Net Carrying Amount	$ 39,716	$ 52,638

Goodwill, In-Process Research and Development and Intellectual Property - Summary of Estimated Future Amortization Expense of Intangible Assets (Detail) - Intellectual Property [Member] - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
2019	$ 10,540
2020	10,538
2021	10,538
2022	7,915
2023	42
Thereafter	143
Total	$ 39,716	$ 52,638

Income Taxes - Summary of Components of Income Tax Benefit (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current income taxes
Federal									$ 0	$ 0	$ 0
State									0	0	0
Foreign									0	0	0
Deferred income taxes
Federal									0	0	0
State									0	0	0
Foreign									(3,377)	(3,300)	(5,523)
Income tax benefit	$ (823)	$ (781)	$ (883)	$ (890)	$ (963)	$ (738)	$ (741)	$ (858)	$ (3,377)	$ (3,300)	$ (5,523)

Income Taxes - Schedule of Income (Loss) From Operations Before Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
United States									$ (44,744)	$ (124,418)	$ (88,624)
Foreign									(20,410)	(23,678)	(36,879)
Loss before income taxes	$ (7,264)	$ (20,987)	$ (35,131)	$ (1,772)	$ (77,119)	$ (39,251)	$ (15,454)	$ (16,272)	$ (65,154)	$ (148,096)	$ (125,503)

Income Taxes - Summary of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Noncurrent deferred tax assets:
Stock-based compensation	$ 2,281	$ 2,216
Inventory	0	375
Accrued expenses and other	795	637
Research credit carryforward	6,182	5,540
Fixed assets	392	450
Capitalized start-up costs and other intangibles	1,859	2,130
Net operating loss carryforwards	74,566	64,300
Deferred Tax Assets, Gross	86,075	75,648
Valuation allowance	(81,337)	(71,520)
Net noncurrent deferred tax asset	4,738	4,128
Noncurrent deferred tax liabilities
Fixed assets	(686)	(334)
Purchase accounting intangibles	(8,772)	(12,183)
Net noncurrent deferred tax liability	(9,458)	(12,517)
Net deferred tax asset (liability)	$ (4,720)	$ (8,389)

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Valuation allowance, deferred tax asset, change in amount	$ 9,800,000
Operating loss carry forwards	74,566,000	$ 64,300,000
Unrecognized tax benefits	1,363,000	1,202,000	$ 1,048,000	$ 862,000
Accrued interest or penalties related to uncertain tax positions	$ 0	$ 0
Statutory income tax rate	21.00%	34.00%	34.00%
Decrease in deferred tax assets due to newly enacted tax rate		$ 36,100,000
Decrease in valuation allowance due to newly enacted tax rate		36,100,000
GILTI deferred amounts		$ 0
GILTI income tax	$ 0
Domestic Tax Authority [Member]
Income Tax Contingency [Line Items]
Operating loss carry forwards	290,900,000
Operating loss carryforwards subject to expiration	$ 254,500,000
Operating loss carryforwards expiration period	2027
Remaining operating loss carryforwards	$ 36,400,000
State and Local Jurisdiction [Member]
Income Tax Contingency [Line Items]
Operating loss carry forwards	234,600,000
Operating loss carryforwards subject to expiration	$ 231,700,000
Operating loss carryforwards expiration period	2022
Remaining operating loss carryforwards	$ 2,900,000
Foreign Tax Authority [Member] \| Italy
Income Tax Contingency [Line Items]
Operating loss carry forwards	19,400,000
Foreign Tax Authority [Member] \| Luxembourg [Member]
Income Tax Contingency [Line Items]
Operating loss carry forwards	$ 200,000
Foreign Tax Authority [Member] \| Switzerland [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards expiration period	2023
Operating loss carry forwards	$ 24,100,000
Foreign Tax Authority [Member] \| Japan [Member]
Income Tax Contingency [Line Items]
Operating loss carryforwards expiration period	2028
Operating loss carry forwards	$ 800,000
Research Tax Credit Carryforward [Member]
Income Tax Contingency [Line Items]
Tax credit carry forward, amount	$ 6,200,000
Tax credit carry forward expiration period	2027

Income Taxes - Summary of Change in Gross Unrecognized Tax Positions (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Beginning balance	$ 1,202	$ 1,048	$ 862
Gross increases for tax positions related to current periods	161	143	186
Gross increases for tax positions related to prior periods	0	11	0
Ending balance	$ 1,363	$ 1,202	$ 1,048

Income Taxes - Summary of Provision for Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
United States federal tax statutory rate, Amount									$ (13,682)	$ (50,352)	$ (42,671)
State taxes (net of deferred benefit), Amount									(1,080)	(4,663)	(2,487)
Non-deductible expenses, Amount									(1,320)	466	667
Change in fair market value of contingent consideration, Amount									(256)	777
Warrant remeasurement and financing costs, Amount									(3,630)	(32,348)
Research & Development Credits, Amount									(803)	(712)	(922)
Change in unrecognized tax benefits, Amount									161	142	186
Foreign tax rate differential, Amount									(96)	3,619	3,969
Goodwill impairment, Amount											20,816
Change in enacted tax rates and other, net, Amount									252	35,440	(1,069)
Change in valuation allowance, Amount									9,817	(20,365)	15,988
Income tax benefit	$ (823)	$ (781)	$ (883)	$ (890)	$ (963)	$ (738)	$ (741)	$ (858)	$ (3,377)	$ (3,300)	$ (5,523)
United States federal tax statutory rate, Percent of Pretax Earnings									21.00%	34.00%	34.00%
State taxes (net of deferred benefit), Percent of Pretax Earnings									1.70%	3.10%	2.00%
Non-deductible expenses, Percent of Pretax Earnings									2.00%	(0.30%)	(0.50%)
Change in fair market value of contingent consideration, Percent of Pretax Earnings									0.40%	(0.50%)
Warrant remeasurement and financing costs, Percent of Pretax Earnings									(5.60%)	(21.80%)
Research & Development Credits, Percent of Pretax Earnings									1.20%	0.50%	0.70%
Change in unrecognized tax benefits, Percent of Pretax Earnings									(0.20%)	(0.10%)	(0.10%)
Foreign tax rate differential, Percent of Pretax Earnings									0.10%	(2.40%)	(3.20%)
Goodwill impairment, Percent of Pretax Earnings											(16.60%)
Change in enacted tax rates and other, net, Percent of Pretax Earnings									(0.30%)	(24.10%)	0.80%
Change in valuation allowance, Percent of Pretax Earnings									(15.10%)	13.80%	(12.70%)
Provision for income taxes, Percent of Pretax Earnings									5.20%	2.20%	4.40%

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accrued Liabilities Current [Abstract]
Compensation and benefits	$ 6,225	$ 4,533
Consulting and other vendors	895	1,414
Other	539	504
Royalties	498	41
Legal and professional fees	432	386
Deferred rent	391	595
Taxes and other assessments	383	3,192
Interest	256	309
Total	$ 9,619	$ 10,974

Notes Payable - Additional Information (Detail) - USD ($)			1 Months Ended		12 Months Ended
	May 23, 2018	May 10, 2017	May 31, 2018	May 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Oct. 23, 2018	Apr. 28, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Loss on Extinguishment of notes payable					$ (1,400,000)	$ (308,000)
Issue of warrants to purchase shares of company's common stock								24,900,000
Notes Payable [Member]
Debt Instrument [Line Items]
Debt issuance costs paid to prior lenders and third parties					371,000
Debt issuance cost					280,000
Debt unamortized balance									$ 107,000
Notes Payable [Member] \| Loss on Extinguishment of Notes Payable [Member]
Debt Instrument [Line Items]
Debt unamortized balance				$ 63,000
Hercules Loan Agreement [Member]
Debt Instrument [Line Items]
Debt discount liability, facility fee recorded as debt discount			$ 287,000
Debt Instrument, redemption price amount			$ 680,000
Hercules Loan Agreement [Member] \| Notes Payable [Member] \| Interest Expense [Member]
Debt Instrument [Line Items]
Loss on Extinguishment of notes payable					$ (1,400,000)
Hercules Loan Agreement [Member] \| Term Loan [Member]
Debt Instrument [Line Items]
Note issuance date					May 23, 2018
Term loans aggregate principal amount	$ 40,000,000
Repayment of term loans period	18 months
Debt instrument amortization schedule	18 months
Debt instrument repayment term					The Company is entitled to make interest-only payments until December 1, 2020, and at the end of the interest-only period, the Company will be required to repay the term loans over an eighteen-month period based on an eighteen-month amortization schedule, with a final maturity date of June 1, 2022.
Interest only payment date					Dec. 01, 2020
Maturity date of the term loans					Jun. 01, 2022
Debt discount liability, facility fee recorded as debt discount	$ 400,000
Debt issuance costs recorded as debt discount	$ 1,100,000
Prepayment fee percentage	6.95%
Term loans payment terms					In addition, the Company is permitted to prepay the term loans in full at any time, with a prepayment fee of 3.0% of the outstanding principal amount of the loan in the first year after the Initial Funding Date, 2.0% if the prepayment occurs in the second year after the Initial Funding Date and 1.0% thereafter. Upon prepayment of the term loans in full or repayment of the terms loans at the maturity date or upon acceleration, the Company is required to pay a final fee of 6.95% of the aggregate principal amount of term loans funded. The final payment fee is accreted to interest expense over the life of the term loan and included within notes payable on the consolidated balance sheet.
Percentage outstanding principal balance of term loans required to be maintained	120.00%
Percentage of maintained cash and investment property in accounts of aggregate cash of parent and subsidiaries	80.00%
Amount of investment to any future equity offering	$ 2,000,000
Hercules Loan Agreement [Member] \| Term Loan [Member] \| Fixed Rate and Prime Rate [Member]
Debt Instrument [Line Items]
Term loans interest rate	5.00%
Hercules Loan Agreement [Member] \| Term Loan [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Term loans fixed interest rate	9.55%
Hercules Loan Agreement [Member] \| Term Loan [Member] \| First Year After Initial Funding Date [Member]
Debt Instrument [Line Items]
Prepayment fee percentage	3.00%
Hercules Loan Agreement [Member] \| Term Loan [Member] \| Second Year After Initial Funding Date [Member]
Debt Instrument [Line Items]
Prepayment fee percentage	2.00%
Hercules Loan Agreement [Member] \| Term Loan [Member] \| Second Year After Initial Funding Date And Thereafter [Member]
Debt Instrument [Line Items]
Prepayment fee percentage	1.00%
Hercules Loan Agreement [Member] \| Term Loan [Member] \| First Tranche [Member]
Debt Instrument [Line Items]
Term loans aggregate principal amount	$ 20,000,000
Hercules Loan Agreement [Member] \| Term Loan [Member] \| Second Tranche [Member]
Debt Instrument [Line Items]
Term loans aggregate principal amount							$ 10,000,000
Hercules Loan Agreement [Member] \| Term Loan [Member] \| Third Tranche [Member]
Debt Instrument [Line Items]
Term loans aggregate principal amount							$ 10,000,000
Term loans fixed interest rate	9.20%
Loan and Security Agreement [Member]
Debt Instrument [Line Items]
Debt discount liability, facility fee recorded as debt discount				255,000
Debt Instrument, redemption price amount				$ 1,300,000
Loan and Security Agreement [Member] \| Notes Payable [Member] \| Interest Expense [Member]
Debt Instrument [Line Items]
Loss on Extinguishment of notes payable						(308,000)
Loan and Security Agreement [Member] \| Term Loan [Member]
Debt Instrument [Line Items]
Debt issuance costs recorded as debt discount		$ 1,200,000
Warrant expiration period		5 years
Loan and Security Agreement [Member] \| Term Loan [Member] \| Innovatus Life Sciences Lending Fund I, LP [Member]
Debt Instrument [Line Items]
Note issuance date		May 10, 2017
Term loans aggregate principal amount		$ 17,000,000
Repayment of term loans period		2 years
Debt instrument amortization schedule		24 months
Maturity date of the term loans					May 10, 2021
Term loans fixed interest rate		11.00%
Term loans fixed interest rate, paid in-kind percentage		2.50%
Interest only payment period		24 months
Loan and Security Agreement [Member] \| Term Loan [Member] \| First Tranche [Member]
Debt Instrument [Line Items]
Debt discount liability, facility fee recorded as debt discount		$ 170,000
Warrants, exercise price		$ 1.00
Estimated fair value of warrants		$ 300,000
Unamortized debt discount					$ 0	$ 1,000,000
Loan and Security Agreement [Member] \| Term Loan [Member] \| First Tranche [Member] \| Innovatus Life Sciences Lending Fund I, LP [Member]
Debt Instrument [Line Items]
Term loans aggregate principal amount		$ 14,000,000
Loan and Security Agreement [Member] \| Term Loan [Member] \| First Tranche [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Issue of warrants to purchase shares of company's common stock		1,244,746

Notes Payable - Summary of Future Principal Payments under Hercules Loan Agreement (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Notes payable, net of debt discount	$ 28,937	$ 8,385
Hercules Loan Agreement [Member] \| Term Loan [Member]
Debt Instrument [Line Items]
2020	1,466
2021	18,527
2022	10,007
Total	30,000
Less: Unamortized discount	(1,063)
Notes payable, net of debt discount	$ 28,937

Stock-Based Compensation - Additional Information (Detail)		1 Months Ended	12 Months Ended
	Sep. 03, 2013	Sep. 30, 2006 shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2014 shares	Dec. 31, 2013 shares	May 24, 2018 shares	May 25, 2017 shares	Jun. 08, 2016 shares	May 07, 2015 shares	Oct. 29, 2013 shares	Jun. 19, 2012 shares	Dec. 31, 2011 shares	Dec. 31, 2009 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance								40,940,000	25,940,000
Stock-based compensation expense \| $			$ 9,039,000	$ 7,078,000	$ 5,033,000
Expected dividend yield			0.00%	0.00%	0.00%
Aggregate intrinsic value of stock options outstanding \| $			$ 9,200,000
Aggregate intrinsic value of stock options exercisable \| $			2,300,000
Aggregate intrinsic value of stock options vested or expected to vest \| $			8,700,000
Intrinsic value of options exercised \| $			9,313,000	$ 2,179,000	$ 519,000
Proceeds from options exercised \| $			$ 7,128,000	$ 438,000	$ 166,000
Options granted			8,705,617	4,746,250	5,368,755
Weighted-average grant date fair value of options granted \| $ / shares			$ 1.59	$ 0.82	$ 1.30
Unrecognized employee stock-based compensation expense \| $			$ 14,429,000
Expected weighted-average period for compensation expense recognition			2 years 8 months 12 days
Incentive Compensation Plan 2006 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award limitations for options or stock appreciation rights per-person		80,000
Stock option, number of shares authorized for issuance														3,378,189	1,110,053
Options vesting period			4 years
Options expiration period			10 years
Stock Appreciation Rights (SARs) [Member] \| Incentive Compensation Plan 2007 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award limitations for options or stock appreciation rights per-person						1,000,000	200,000
Other Stock Based Awards [Member] \| Incentive Compensation Plan 2007 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award limitations for options or stock appreciation rights per-person						500,000	100,000
June 19, 2012 Amendment [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance													1,000,000
October 29, 2013 Amendment [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance												4,940,000
May 7, 2015 Amendment [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance											11,940,000
June 8, 2016 Amendment [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance										18,940,000
Merger Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option exchange ratio	1.1533

Stock-Based Compensation - Summary of Share Based Fair Value Assumptions (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%	0.00%
Expected volatility, Minimum	73.00%	70.00%
Expected volatility, Maximum	75.00%	72.00%
Expected volatility			47.00%
Risk-free interest rate , Minimum	2.35%	1.84%	1.13%
Risk-free interest rate , Maximum	3.02%	2.29%	2.09%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	5 years 6 months	5 years 6 months	5 years 6 months
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	6 years 1 month 6 days	6 years 3 months 18 days	6 years 3 months 18 days

Stock-Based Compensation - Schedule of Stock Option Activity (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share Based Compensation Stock Options Activity [Abstract]
Number of Shares, Outstanding, Beginning balance	15,693,675
Number of Shares, Granted	8,705,617	4,746,250	5,368,755
Number of Shares, Forfeited	(925,495)
Number of Shares, Cancelled	(192,633)
Number of Shares, Exercised	(3,381,533)
Number of Shares, Outstanding, Ending balance	19,899,631	15,693,675
Weighted Average Exercise Price, Outstanding	$ 2.32
Weighted Average Exercise Price, Granted	2.39
Weighted Average Exercise Price, Forfeited	1.59
Weighted Average Exercise Price, Cancelled	2.11
Weighted Average Exercise Price, Exercised	2.11
Weighted Average Exercise Price, Outstanding	$ 2.42	$ 2.32
Weighted-Average Remaining Contractual Term (Years)	7 years 9 months 25 days	7 years 9 months 10 days

Stock-Based Compensation - Schedule of Stock Options Outstanding (Detail)	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award Options Additional Disclosures [Abstract]
Number of Shares, Exercisable \| shares	7,574,932
Vested or expected to vest, Number of Shares \| shares	18,960,684
Exercisable, Weighted-Average Exercise Price \| $ / shares	$ 2.72
Vested or expected to vest, Weighted-Average Exercise Price \| $ / shares	$ 2.42
Weighted-Average Remaining Contractual Term, Exercisable	6 years 6 months 10 days
Weighted-Average Remaining Contractual Term, Vested or expected to vest	7 years 9 months 3 days

Restricted Stock Units - Summary of Restricted Stock Unit Activity (Detail) - Nonvested Restricted Stock Units [Member] - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Restricted Stock Units Outstanding, Beginning balance	4,394,656	895,328	422,500
Number of Restricted Stock Units Outstanding, Granted	2,215,151	3,873,000	660,331
Number of Restricted Stock Units Outstanding, Vested	(1,605,997)	(337,618)	(187,503)
Number of Restricted Stock Units Outstanding, Forfeited	(36,666)	(36,054)
Number of Restricted Stock Units Outstanding, Ending balance	4,967,144	4,394,656	895,328
Weighted Average Grant Date Fair Value, Unvested beginning balance	$ 1.15	$ 3.53	$ 3.64
Weighted Average Grant Date Fair Value, Granted	2.20	0.82	3.74
Weighted Average Grant Date Fair Value, Vested	1.34	3.46	4.53
Weighted Average Grant Date Fair Value, Forfeited	1.36	3.60
Weighted Average Grant Date Fair Value, Unvested ending balance	$ 1.56	$ 1.15	$ 3.53

Restricted Stock Units - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee service share-based compensation, nonvested awards, compensation cost not yet recognized, period for recognition	2 years 8 months 12 days
Nonvested Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred compensation liability, Current, total	$ 2,947,000	$ 1,751,000	$ 1,463,000
Employee service share-based compensation, nonvested awards, compensation not yet recognized, share-based awards other than options	$ 4,900,000
Employee service share-based compensation, nonvested awards, compensation cost not yet recognized, period for recognition	1 year 8 months 12 days

Warrants - Additional Information (Detail) $ / shares in Units, $ in Millions								12 Months Ended
	Sep. 12, 2017 USD ($) $ / shares shares	May 10, 2017 $ / shares shares	Apr. 28, 2017 $ / shares shares	Aug. 14, 2015 $ / shares shares	Sep. 26, 2014 $ / shares shares	Mar. 22, 2013 USD ($) Investor $ / shares shares	Jan. 17, 2012 $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2013 shares	Sep. 03, 2013 shares
Class of Warrant or Right [Line Items]
Offering price \| $ / shares			$ 1.00
Warrants to purchase common shares			24,900,000
Warrants outstanding												1,200,000
Warrants exercised			0
Warrants Not Settleable in Cash [Member]
Class of Warrant or Right [Line Items]
Share-based compensation arrangement by share-based payment award, Equity instruments other than options, aggregate intrinsic value, outstanding \| $								$ 5.3	$ 11.2	$ 0.0
Minimum [Member]
Class of Warrant or Right [Line Items]
Percentage of warrants exercisability limitation percentage								4.99%
Outstanding voting stock acquisition minimum threshold percentage to assume warrant obligations								50.00%
Series A Warrant [Member]
Class of Warrant or Right [Line Items]
Warrants, exercise price \| $ / shares			$ 1.00
Warrant expiration date			Oct. 31, 2017
Series B Warrant [Member]
Class of Warrant or Right [Line Items]
Warrants, exercise price \| $ / shares			$ 1.00					$ 1.00
Warrants exercised								8,893,700	7,052,215
Service Warrants [Member] \| Service Agreement [Member]
Class of Warrant or Right [Line Items]
Warrants, exercise price \| $ / shares	$ 1.00
Warrant, expiration period	10 years
Warrants exercised								650,000	0
Common stock warrants issued	950,000
Percentage of vesting date of execution agreement	25.00%
Percentage of vesting completion of hiring the sales term	50.00%
Percentage of vesting achieving cumulative product revenue	25.00%
Achieving cumulative product revenue \| $	$ 15.0
Recognized initial expense \| $									$ 0.6
Common Stock [Member]
Class of Warrant or Right [Line Items]
Number of common stock or warrants in each unit			1
Common Stock [Member] \| Series A Warrant [Member]
Class of Warrant or Right [Line Items]
Warrants, exercise price \| $ / shares			$ 1.00
Number of common stock or warrants in each unit			1
Common Stock [Member] \| Series B Warrant [Member]
Class of Warrant or Right [Line Items]
Warrants, exercise price \| $ / shares			$ 1.00
Number of common stock or warrants in each unit			0.75
First Amended SVB Loan Agreement [Member]
Class of Warrant or Right [Line Items]
Warrants, exercise price \| $ / shares					$ 4.015
Warrant, expiration period					7 years
Warrants exercised								27,880	0	0
Stock issued due to exercise of options								8,580
Common stock warrants issued					38,324
Second Amended SVB Loan Agreement [Member]
Class of Warrant or Right [Line Items]
Warrants, exercise price \| $ / shares				$ 3.10
Warrant, expiration period				7 years
Warrants exercised								67,742	0	0
Stock issued due to exercise of options								31,535
Common stock warrants issued				112,903
Stock Purchase Agreement 2013 [Member] \| 2013 PIPE investors [Member]
Class of Warrant or Right [Line Items]
Number of investors \| Investor						17
Stock issued, shares						2,420,000
Offering price \| $ / shares						$ 1.25
Proceeds from PIPE \| $						$ 3.0
Warrants to purchase common shares						1,209,600
Warrants, exercise price \| $ / shares						$ 1.65
Warrant, expiration period						5 years
Merger Agreement [Member]
Class of Warrant or Right [Line Items]
Exchange ratio												1.1533
Loan and Security Agreement [Member] \| Term Loan [Member]
Class of Warrant or Right [Line Items]
Warrant, expiration period		5 years
Warrants exercised								0
Loan and Security Agreement [Member] \| Term Loan [Member] \| First Tranche [Member]
Class of Warrant or Right [Line Items]
Warrants, exercise price \| $ / shares		$ 1.00
Loan and Security Agreement [Member] \| Maximum [Member] \| Term Loan [Member] \| First Tranche [Member]
Class of Warrant or Right [Line Items]
Warrants to purchase common shares		1,244,746
Related Parties [Member] \| Stock Purchase Agreement 2013 [Member] \| 2013 PIPE investors [Member]
Class of Warrant or Right [Line Items]
Stock issued, shares						1,280,000
Warrants to purchase common shares						640,000
Warrants exercised								800,000	240,000	0
Prior Lenders [Member]
Class of Warrant or Right [Line Items]
Warrants to purchase common shares							279,588
Warrants, exercise price \| $ / shares							$ 1.45
Warrant, expiration period							10 years
Warrants exercised								139,794	0	0	139,794
Stock issued due to exercise of options								104,845			112,766

Warrants - Summary of Warrant Activity (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Class of Warrant or Right [Line Items]
Weighted Average Exercise Price, Expired	$ 2.11
Warrants Not Settleable in Cash [Member]
Class of Warrant or Right [Line Items]
Number of Restricted Stock Units Outstanding, Beginning balance	13,162,668	1,426,622	1,426,622
Number of Warrants, Granted		45,769,746
Number of Warrants, Exercised	(8,737,631)	(34,033,700)
Number of Warrants, Expired	(95,600)
Number of Restricted Stock Units Outstanding, Ending balance	4,329,437	13,162,668	1,426,622	1,426,622
Weighted Average Exercise Price, Outstanding, Beginning balance	$ 1.08	$ 1.81	$ 1.81
Weighted Average Exercise Price, Granted		1.00
Weighted Average Exercise Price, Exercised	1.09	1.00
Weighted Average Exercise Price, Expired	1.65
Weighted Average Exercise Price, Outstanding, Ending balance	$ 1.03	$ 1.08	$ 1.81	$ 1.81
Weighted Average Remaining Contractual Life, Outstanding	3 years 8 months 12 days	4 years 6 months	2 years 2 months 12 days	3 years 2 months 12 days
Weighted Average Remaining Contractual Life, Granted		4 years 9 months 18 days
Weighted Average Fair Value, Outstanding, Beginning balance	$ 0.39	$ 1.54	$ 1.54
Weighted Average Fair Value, Granted		0.22
Weighted Average Fair Value, Outstanding, Ending balance	$ 0.26	$ 0.39	$ 1.54	$ 1.54

Restructuring - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
	May 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost And Reserve [Line Items]
Inventory write-down related to restructuring				$ 2,565,000
Restructuring and other charges				3,064,000
Restructuring and other charges related to other non-cash charges				2,556,000
Disposal of long-lived assets		$ 0	$ 0	1,000,000
SurgiBot System [Member]
Restructuring Cost And Reserve [Line Items]
Inventory write-down related to restructuring		0	0	2,600,000
SurgiBot System [Member] \| Patents [Member]
Restructuring Cost And Reserve [Line Items]
Write-off of intellectual property		0	0	$ 1,600,000
Headcount, Discontinued Efforts and Cancellation of Contracts [Member] \| SurgiBot System [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	$ 5,700,000
Inventory write-down related to restructuring	2,600,000
Restructuring and other charges	3,100,000
Restructuring amount paid in cash	500,000
Employee severance costs	400,000
Restructuring and other charges related to cancellation of contracts	100,000
Restructuring and other charges related to other non-cash charges	2,600,000
Disposal of long-lived assets	1,000,000
Headcount, Discontinued Efforts and Cancellation of Contracts [Member] \| SurgiBot System [Member] \| Accrued Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Total future payments under plan		$ 0	$ 0
Headcount, Discontinued Efforts and Cancellation of Contracts [Member] \| SurgiBot System [Member] \| Patents [Member]
Restructuring Cost And Reserve [Line Items]
Write-off of intellectual property	$ 1,600,000

Purchase Agreement, Controlled Equity Offering and Public Offering of Common Stock - Additional Information (Detail) - USD ($)						4 Months Ended	12 Months Ended
	Dec. 28, 2018	Aug. 31, 2017	Apr. 28, 2017	Feb. 09, 2016	Feb. 20, 2015	Apr. 27, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 16, 2016
Stockholders Equity Common Stock [Line Items]
Warrants to purchase common shares			24,900,000
Offering price			$ 1.00
Gross proceeds from public offering			$ 24,900,000
Net proceeds from public offering			$ 23,200,000
Warrants exercised			0
Series B Warrant [Member]
Stockholders Equity Common Stock [Line Items]
Warrants exercised							8,893,700	7,052,215
Stifel, Nicolaus & Company, Incorporated [Member]
Stockholders Equity Common Stock [Line Items]
Percentage of commission paid	3.00%	3.00%
Total shares of common stock sold							0
Stifel, Nicolaus & Company, Incorporated [Member] \| Maximum [Member]
Stockholders Equity Common Stock [Line Items]
Sale of common stock in an at-the-market offering	$ 75,000,000	$ 50,000,000
Lincoln Park Capital Fund, LLC [Member]
Stockholders Equity Common Stock [Line Items]
Right to sell common stock										25,000,000
Stock issued, shares								3,972,741	300,000
Gross proceeds								$ 5,304,000	$ 412,500
Proceeds from issuance of common stock, net of issuance costs								$ 5,304,000	$ 392,500
Lincoln Park Capital Fund, LLC [Member] \| Commitment Shares [Member]
Stockholders Equity Common Stock [Line Items]
Stock issued, shares						345,421
Cantor Fitzgerald & Co. [Member]
Stockholders Equity Common Stock [Line Items]
Percentage of commission paid				3.00%	3.00%
Cantor Fitzgerald & Co. [Member] \| Maximum [Member]
Stockholders Equity Common Stock [Line Items]
Sale of common stock in an at-the-market offering				$ 43,600,000	$ 25,000,000
Common Stock [Member]
Stockholders Equity Common Stock [Line Items]
Number of common stock or warrants in each unit			1
Common Stock [Member] \| Series A Warrant [Member]
Stockholders Equity Common Stock [Line Items]
Number of common stock or warrants in each unit			1
Common Stock [Member] \| Series B Warrant [Member]
Stockholders Equity Common Stock [Line Items]
Number of common stock or warrants in each unit			0.75

Purchase Agreement, Controlled Equity Offering and Public Offering of Common Stock - Schedule of Amounts Offered and Sold under 2015, 2016 and 2017 Sales Agreement (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stifel, Nicolaus & Company, Incorporated [Member]
Sale And Issue Of Shares Under Agreement [Line Items]
Total shares of common stock sold	0
Stifel, Nicolaus & Company, Incorporated [Member] \| 2017 Sales Agreement [Member]
Sale And Issue Of Shares Under Agreement [Line Items]
Total shares of common stock sold		15,998,500
Average price per share		$ 3.13
Gross proceeds		$ 50,000
Commissions earned by Cantor		1,500
Other issuance costs		$ 97
Cantor Fitzgerald & Co. [Member] \| 2016 Sales Agreement [Member]
Sale And Issue Of Shares Under Agreement [Line Items]
Total shares of common stock sold			8,763,400
Average price per share			$ 4.70
Gross proceeds			$ 41,156
Commissions earned by Cantor			1,235
Other issuance costs			$ 185
Cantor Fitzgerald & Co. [Member] \| 2015 Sales Agreement [Member]
Sale And Issue Of Shares Under Agreement [Line Items]
Total shares of common stock sold			5,710,200	2,014,300
Average price per share			$ 3.23	$ 3.25
Gross proceeds			$ 18,454	$ 6,546
Commissions earned by Cantor			$ 553	197
Other issuance costs				$ 259

Basic and Diluted Net Loss per Share - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Basic And Diluted Earning Per Share [Abstract]
Adjustment to weighted average outstanding common shares	0	0	0

Basic and Diluted Net Loss per Share - Summary of Potential Common Shares (Detail) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	29,196,212	33,250,999	14,810,501
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	19,899,631	15,693,675	12,488,551
Stock Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	4,329,437	13,162,668	1,426,622
Nonvested Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	4,967,144	4,394,656	895,328

Related Person Transactions - Additional Information (Detail) $ / shares in Units, € in Millions				1 Months Ended	12 Months Ended
	Jan. 04, 2017 EUR (€) shares	Dec. 30, 2016 EUR (€) shares	Sep. 21, 2015 USD ($) shares	Nov. 30, 2016 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jan. 04, 2017 $ / shares
Related Party Transaction [Line Items]
Fair value of contingent consideration					$ 10,637,000	$ 12,418,000
Senhance Surgical Robotic System Acquisition [Member]
Related Party Transaction [Line Items]
Acquisition price			$ 92,577,000	$ 400,000
Reduction of contingent consideration					1,000,000	2,000,000
Common shares issued \| shares			15,543,413
Fair value of contingent consideration			$ 23,900,000		10,600,000
Senhance Surgical Robotic System Acquisition [Member] \| Second Tranche [Member]
Related Party Transaction [Line Items]
Reduction of contingent consideration \| €		€ (5.0)
Common shares issued \| shares		3,722,685
Aggregate fair market value of common stock \| €		€ 5.0
Fair value of contingent consideration \| €	€ 5.0
Share price \| $ / shares								$ 1.404
Number of consecutive trading days	10 days
Sofar [Member]
Related Party Transaction [Line Items]
Expenses for administrative services with related party					$ 0	$ 55,000	$ 232,000
Service agreement termination period					2017
Sofar [Member] \| Senhance Surgical Robotic System Acquisition [Member] \| Second Tranche [Member]
Related Party Transaction [Line Items]
Common shares issued \| shares	3,722,685
Sofar [Member] \| TransEnterix Italia [Member] \| Common Stock [Member]
Related Party Transaction [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners					8.90%	9.70%
1Med S.A [Member] \| Service Supply Agreement [Member]
Related Party Transaction [Line Items]
Expenses incurred under related party transactions					$ 71,000,000
Synecor, LLC [Member]
Related Party Transaction [Line Items]
Payments to Acquire in Process Research and Development					$ 24,000	$ 0	$ 5,000

Commitments and Contingencies - Additional Information (Detail) € in Millions									12 Months Ended
	Jan. 08, 2018	Dec. 27, 2017	Jan. 04, 2017 EUR (€)	Dec. 30, 2016 EUR (€) shares	Sep. 21, 2015 USD ($) shares	Jun. 12, 2014	Oct. 25, 2013	Nov. 02, 2009	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Operating Leased Assets [Line Items]
Fair value of contingent consideration									$ 10,637,000	$ 12,418,000
Liability or related charge recorded for legal contingencies									0
Corporate offices [Member]
Operating Leased Assets [Line Items]
Lease expiration date	Dec. 31, 2019					Jun. 30, 2018
Operating lease agreement period								5 years
Operating lease amended extension period						3 years 2 months
Operating lease, lease not yet commenced, term of contract	18 months
Operating lease, renew option period						3 years
Operating lease, lease not yet commenced, renewal term	5 years
Operating lease, lease not yet commenced, existence of option to extend	true
Warehouse [Member]
Operating Leased Assets [Line Items]
Operating lease agreement period							4 years 4 months
Operating lease additional renewed period							6 years
Operating lease termination on lease effective date		Jan. 31, 2018
Operating leases, rent expense									1,186,000	1,135,000	$ 907,000
Senhance Surgical Robotic System Acquisition [Member]
Operating Leased Assets [Line Items]
Contingent consideration related to acquisition									1,000,000	$ 2,000,000
Common shares issued \| shares					15,543,413
Fair value of contingent consideration					$ 23,900,000				10,600,000
Senhance Surgical Robotic System Acquisition [Member] \| License and Supply Agreements [Member]
Operating Leased Assets [Line Items]
Commitments under agreements, in 2019									7,301,000
Commitments under agreements, in 2020									756,000
Commitments under agreements, in 2021									573,000
Commitments under agreements, in 2022									573,000
Commitments under agreements, in 2023									573,000
Commitments under agreements, thereafter until termination in 2027									$ 1,700,000
Senhance Surgical Robotic System Acquisition [Member] \| Second Tranche [Member]
Operating Leased Assets [Line Items]
Contingent consideration related to acquisition \| €				€ (5.0)
Common shares issued \| shares				3,722,685
Aggregate fair market value of common stock \| €				€ 5.0
Fair value of contingent consideration \| €			€ 5.0
TransEnterix Italia [Member] \| Research and Development and Demonstration Facilities [Member]
Operating Leased Assets [Line Items]
Operating lease agreement period										6 years

Commitments and Contingencies - Summary of Future Minimum Payments and Operating Lease Obligations (Detail) $ in Thousands	Dec. 31, 2018 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2019	$ 929
2020	399
2021	385
2022	175
2023	38
Total	$ 1,926

Quarterly Results of Operation (Unaudited) - Summary of Unaudited Quarterly Results of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 7,524	$ 5,422	$ 6,389	$ 4,767	$ 3,398	$ 183	$ 1,584	$ 1,946	$ 24,102	$ 7,111
Cost of revenue	5,635	4,249	3,732	2,555	3,500	921	972	1,334	16,171	6,727
Gross profit	1,889	1,173	2,657	2,212	(102)	(738)	612	612	7,931	384	$ 450
Amortization of intangible assets	2,624	2,674	2,743	2,827	2,714	1,821	1,687	1,636	10,868	7,858	6,967
Change in fair value of contingent consideration	(1,092)	(1,358)	812	627	800	773	(774)	1,227	(1,011)	2,026	482
Acquisition related costs	302	345							647
Gain from sale of SurgiBot assets, net	75	44	37	(11,996)					(11,840)
Issuance costs for warrants							627			627
Other operating expenses	18,205	14,343	14,954	13,911	14,298	12,337	11,538	13,627	61,413	51,800
Change in fair value of warrant liabilities	(10,118)	8,760	17,507	(1,829)	58,521	22,887	2,326		14,320	83,734
Reversal of transfer fee accrual		(2,994)							(2,994)
Interest income, interest expense and other expense	(843)	346	1,735	444	684	695	662	394	1,682	2,435
Loss before income taxes	(7,264)	(20,987)	(35,131)	(1,772)	(77,119)	(39,251)	(15,454)	(16,272)	(65,154)	(148,096)	(125,503)
Income tax benefit	823	781	883	890	963	738	741	858	3,377	3,300	5,523
Net loss	$ (6,441)	$ (20,206)	$ (34,248)	$ (882)	$ (76,156)	$ (38,513)	$ (14,713)	$ (15,414)	$ (61,777)	$ (144,796)	$ (119,980)
Net loss per share - basic and diluted	$ (0.03)	$ (0.10)	$ (0.17)	$ 0.00	$ (0.40)	$ (0.26)	$ (0.11)	$ (0.13)	$ (0.30)	$ (0.97)	$ (1.07)