Hansen Medical (HNSN) 10-K 25 Apr 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Apr. 15, 2016	Jun. 30, 2015
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Trading Symbol	HNSN
Entity Registrant Name	HANSEN MEDICAL INC
Entity Central Index Key	1,276,591
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	Accelerated Filer
Entity Common Stock, Shares Outstanding		18,989,280
Entity Public Float			$ 75.4

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 20,375	$ 24,528
Short-term investments	1,501	1,973
Accounts receivable, net of allowance of $23 and $0 at December 31, 2015 and 2014	4,551	5,121
Inventories	8,659	11,492
Prepaids and other current assets	1,814	1,678
Total current assets	36,900	44,792
Property and equipment, net	2,325	2,328
Restricted cash	6,113	5,376
Other assets	380	1,179
Total assets	45,718	53,675
Current liabilities:
Accounts payable	664	2,534
Accrued liabilities	4,113	4,942
Current portion of deferred revenue	3,923	3,422
Current portion of long-term debt	35,141	0
Total current liabilities	43,841	10,898
Deferred rent, net of current portion	262	366
Deferred revenue, net of current portion	91	105
Long-term debt, net of current portion	0	34,385
Other long-term liabilities	76	152
Total liabilities	$ 44,270	$ 45,906
Commitments and contingencies (Note 7)
Stockholders’ equity:
Preferred stock, par value $0.0001: Authorized: 10,000 shares Issued and outstanding: none	$ 0	$ 0
Common stock, par value $0.0001: Authorized: 30,000 shares Issued and outstanding: 18,897 and 13,326 at December 31, 2015 and 2014	2	13	[1]
Additional paid-in capital	455,585	414,361
Accumulated other comprehensive income	(210)	305
Accumulated deficit	(453,929)	(406,910)
Total stockholders’ equity	1,448	7,769
Total liabilities and stockholders’ equity	$ 45,718	$ 53,675
[1]	The Company’s financial statements have been retroactively adjusted to reflect the reverse stock split of its outstanding shares of common stock at a ratio of one-for-ten effective on September 22, 2015.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) $ in Thousands	Dec. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2014USD ($)$ / sharesshares
Statement of Financial Position [Abstract]
Accounts receivable, allowance | $	$ 23	$ 0
Preferred stock, par value (in USD per share) | $ / shares	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in USD per share) | $ / shares	$ 0.0001	$ 0.0001
Common stock, shares authorized	30,000,000	30,000,000
Common stock, shares issued	18,897,000	13,326,000
Common stock, shares outstanding	18,897,000	13,326,000

Consolidated Statements of Oper

Consolidated Statements of Operations shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2014USD ($)$ / sharesshares	Dec. 31, 2013USD ($)$ / sharesshares
Revenues:
Product		$ 10,719	$ 13,812	$ 11,790
Service		5,349	5,683	5,192
Total revenues		16,068	19,495	16,982
Cost of revenues:
Product		12,016	13,123	11,150
Service		3,049	3,368	2,331
Total cost of revenues		15,065	16,491	13,481
Gross profit		1,003	3,004	3,501
Operating expenses:
Research and development		13,812	18,034	16,139
Selling, general and administrative		23,495	31,254	31,765
Restructuring expense		1,539	0	0
Loss on settlement of litigation (Note 7)		0	0	4,500
Total operating expenses		38,846	49,288	52,404
Loss from operations		(37,843)	(46,284)	(48,903)
Interest income		21	23	25
Loss on extinguishment of debt		0	0	(1,935)
Interest expense		(5,287)	(4,789)	(3,952)
Warrant exchange and change in fair value of warrant liability (Note 10)		(2,993)	(2,914)	0
Other expense, net		(58)	(254)	(842)
Loss before income taxes		(46,160)	(54,218)	(55,607)
Income tax expense		(47)	(28)	(115)
Net loss		(46,207)	(54,246)	(55,722)
Deemed dividend related to beneficial conversion feature of Series A convertible preferred stock and accretion of discount		(35,546)	0	0
Cumulative dividend on Series A convertible preferred stock		(812)	0	0
Net loss attributable to common stockholders		$ (82,565)	$ (54,246)	$ (55,722)
Basic and diluted net loss per share (in USD per share) | $ / shares	[1]	$ (4.89)	$ (4.63)	$ (7.05)
Shares used to compute basic and diluted net loss per share (in shares) | shares	[1]	16,871	11,723	7,905
[1]	The Company’s financial statements have been retroactively adjusted to reflect the reverse stock split of its outstanding shares of common stock at a ratio of one-for-ten effective on September 22, 2015.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net loss	$ (46,207)	$ (54,246)	$ (55,722)
Other comprehensive income (loss), net:
Change in unrealized gains (losses) on investments	(464)	19	276
Amounts reclassified to other income	0	0	627
Foreign currency translation adjustment	(51)	(74)	35
Change in other comprehensive income (loss)	(515)	(55)	938
Comprehensive loss	$ (46,722)	$ (54,301)	$ (54,784)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands		Total	Private Placemen	Convertible Preferred Stock	Common Stock		Common StockPrivate Placemen	Additional Paid- In Capital	Additional Paid- In CapitalPrivate Placemen	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning Balances (in shares) at Dec. 31, 2012	[1]				6,708
Beginning Balances at Dec. 31, 2012		$ 24,739			$ 7			$ 322,252		$ (578)	$ (296,942)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under equity incentive plan (in shares)	[1]				79
Issuance of common stock under equity incentive plan		114						114
Withholding taxes paid on vested restricted stock units		(18)						(18)
Issuance of common stock under employee stock purchase plan (in shares)	[1]				39
Issuance of common stock under employee stock purchase plan		560						560
Issuance of common stock and warrants pursuant to private placement (in shares)	[1]						2,846
Issuance of common stock and warrants pursuant to private placement			$ 37,126				$ 3		$ 37,123
Issuance of common shares in connection with the litigation settlement		4,250						4,250
Issuance of common shares in connection with the litigation settlement, shares	[1]				230
Employee share-based compensation expense		4,889						4,889
Net loss		(55,722)									(55,722)
Change in unrealized gain on investments		276								276
Amounts reclassified to other income		627								627
Translation adjustment		35								35
Ending Balances (in shares) at Dec. 31, 2013	[1]				9,902
Ending Balances at Dec. 31, 2013		16,876			$ 10			369,170		360	(352,664)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under equity incentive plan (in shares)	[1]				187
Issuance of common stock under equity incentive plan		2,586						2,586
Withholding taxes paid on vested restricted stock units		(620)						(620)
Issuance of common stock under employee stock purchase plan (in shares)	[1]				55
Issuance of common stock under employee stock purchase plan		519						519
Issuance of common stock under employee stock purchase plan		14,000			$ 1			13,999
Issuance of common stock upon exercise of Series A warrants, shares	[1]				1,138
Issuance of common stock upon Series B/C warrant exchange		25,877			$ 2			25,875
Issuance of common stock upon Series B/C warrant exchange, shares	[1]				2,044
Employee share-based compensation expense		2,832						2,832
Net loss		(54,246)									(54,246)
Change in unrealized gain on investments		19								19
Amounts reclassified to other income		0
Translation adjustment		(74)								(74)
Ending Balances (in shares) at Dec. 31, 2014	[1]				13,326
Ending Balances at Dec. 31, 2014		$ 7,769			$ 13			414,361		305	(406,910)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under equity incentive plan (in shares)		1
Issuance of common stock under equity incentive plan		$ 3						3
Issuances of common stock from restricted stock units (in shares)	[1]				29
Withholding taxes paid on vested restricted stock units		(26)						(26)
Issuance of common stock under employee stock purchase plan (in shares)	[1]				44
Issuance of common stock under employee stock purchase plan		214						214
Issuance of common stock and warrants pursuant to private placement (in shares)				54
Issuance of common stock and warrants pursuant to private placement				$ 19,678
Beneficial conversion feature of Series A convertible preferred stock		20,224		(20,224)				20,224
Deemed dividend related to beneficial conversion feature of Series A Convertible preferred stock and accretion of discount		(35,546)		35,546				(35,546)
Reclassification of Series E warrant liability to equity		17,774						17,774
Cumulative dividend on Series A convertible preferred stock		(812)		$ 812							(812)
Conversion of shares, stock issued (in shares)				(54)	5,510	[1]
Issuance of common stock upon conversion of Series A convertible preferred stock		35,000		$ (35,000)	$ 5			34,995
Issuance of common stock related to Series A convertible preferred stock dividend		812		$ (812)	$ 1			811
Retire Treasury shares	[1]				(12)
Retire fraction shares due to reverse stock split		0			$ (17)			17
Employee share-based compensation expense		2,758						2,758
Net loss		(46,207)									(46,207)
Change in unrealized gain on investments		(464)								(464)
Amounts reclassified to other income		0
Translation adjustment		(51)								(51)
Ending Balances (in shares) at Dec. 31, 2015	[1]				18,897
Ending Balances at Dec. 31, 2015		$ 1,448			$ 2			$ 455,585		$ (210)	$ (453,929)
[1]	The Company's financial statements have been retroactively adjusted to reflect the reverse stock split of its outstanding shares of common stock at a ratio of one-for-ten effective on September 22, 2015.

Consolidated Statements of Sto7

Consolidated Statements of Stockholders' Equity (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)	Mar. 11, 2015USD ($)
Issuance costs	$ 546
Convertible Preferred Stock
Discount related to warrants		$ 14,776
Issuance costs	$ 546

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities
Net loss	$ (46,207)	$ (54,246)	$ (55,722)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	1,027	2,555	2,949
Stock-based compensation	2,758	2,832	4,889
Warrant exchange and change in fair value of warrant liability	2,993	2,914	0
Payment-in-kind interest on loan	1,058	1,026	597
Reserve for excess and obsolescence in inventory	1,083	706	0
Loss on settlement of litigation	0	0	4,500
Amortization of deferred financing costs and discount on debt	(67)	387	184
Amortization of common stock warrants	0	0	195
Gain on disposal of property and equipment	(36)	0	0
Net realized gains and losses on investments	0	0	677
Loss on extinguishment of debt	0	0	1,935
Provision (recovery) of doubtful accounts	49	(100)	0
Changes in operating assets and liabilities:
Accounts receivable	558	93	120
Inventories	1,044	(775)	(3,069)
Prepaids and other current assets	(127)	227	315
Other assets	564	1,387	(1,464)
Accounts payable	(1,870)	(803)	226
Accrued liabilities	(828)	1,034	568
Deferred revenue	486	412	345
Other liabilities	(179)	(47)	0
Net cash used in operating activities	(37,694)	(42,398)	(42,755)
Cash flows from investing activities
Purchase of property and equipment	(357)	(462)	(550)
Proceeds from sales and maturities of short-term investments	36	0	6,704
Changes in restricted cash	(737)	19	(5,394)
Net cash (used) provided by investing activities	(1,058)	(443)	760
Cash flows from financing activities
Proceeds from issuance of common stock and warrants	35,000	0	39,268
Proceeds from exercise of Series A, B and C warrants	0	37,100	0
Costs related to issuance of preferred stock, common stock and warrants	(546)	(137)	(2,087)
Proceeds from loans	0	0	33,000
Costs related to issuance of loans	0	0	(1,538)
Repayments of loan principal	0	0	(30,000)
Final loan repayment fees	0	0	(2,058)
Proceeds from exercise of common stock options	3	2,586	114
Proceeds from employee stock purchase plan	214	519	560
Withholding taxes paid on vested restricted stock units	(21)	(620)	(18)
Net cash provided by financing activities	34,650	39,448	37,241
Effect of exchange rate changes on cash and cash equivalents	(51)	(74)	0
Net (decrease) in cash and cash equivalents	(4,153)	(3,467)	(4,754)
Cash and cash equivalents at beginning of year	24,528	27,995	32,749
Cash and cash equivalents at end of year	20,375	24,528	27,995
Supplemental disclosures of cash flow information
Cash paid during the period for interest	3,878	3,763	5,207
Supplemental schedule of non-cash investing and financing activities
Equity issuance costs not yet paid	0	0	55
Equipment transfers from inventories to property and equipment	705	779	0
Cumulative dividend on Series A convertible preferred stock	812	0	0
Deemed dividend related to beneficial conversion feature of Series A convertible preferred stock and accretion of discount	$ 35,546	$ 0	$ 0

The Company

The Company	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
The Company	The Company Nature of Operations Hansen Medical, Inc. (the “Company”) develops, manufactures and markets a new generation of medical robotics designed for accurate positioning, manipulation and stable control of catheters and catheter-based technologies. The Company was incorporated in the state of Delaware in September 2002 and is headquartered in Mountain View, California. The Company has wholly-owned subsidiaries located in the United Kingdom and Germany. Both subsidiaries are engaged in marketing the Company’s products in the Europe, Middle East and Africa (“EMEA”) region. Going Concern These consolidated financial statements are prepared on a going concern basis that contemplates the realization of assets and discharge of liabilities in the normal course of business. Since inception, the Company has incurred cumulative net losses of approximately $453.9 million . The Company expects such losses to continue through at least the year ending December 31, 2016 as it continues to commercialize its technologies and develop new applications and products. The Company also has a negative working capital of $6.9 million . The Company continues to face significant uncertainties and challenges. The Company faces uncertainty related to the commercialization of its Magellan TM Robotic System ("Magellan System") and its projected revenue is heavily dependent on a successful commercialization of this system. In addition, the Company is also subject to minimum liquidity requirements under its existing borrowing arrangements with White Oak Global Advisors, LLC ("White Oak"), which require the Company to maintain $15.0 million in liquidity at all times, consisting of at least $13.0 million in cash, cash equivalents, restricted cash and investments and the lesser of $2.0 million or 65% in eligible accounts receivable. Additionally, the Company is required by White Oak to obtain an audit opinion from its independent certified public accountants on the annual financial statements that does not include an explanatory uncertainty paragraph raising substantial doubt about its ability to continue as a going concern or any qualification or exception as to the scope of such audit. As of December 31, 2015, the Company was in compliance with all covenants; however, there was an anticipated default of the covenants listed in Section 6.2(a)(i) and Section 8.2(a), with respect to Section 6.2(a)(i), as of December 31, 2015, which was cured by the Forbearance Agreement as discussed below. As of March 31, 2016, the Company was no longer in compliance with certain covenants and events of default listed in Sections 6.1(c), 6.2(a)(i), 6.2(a)(iv), 6.10, 8.2(a) and 8.2(b) of the loan and security agreement with White Oak (the “Specified Events of Default”). On April 19, 2016, the Company entered into a Forbearance Agreement with White Oak (“Forbearance Agreement”) whereby White Oak granted forbearance of the Specified Events of Default until August 17, 2016 in exchange for a $150,000 non-refundable transaction fee. Pursuant to the Forbearance Agreement, on April 21, 2016, the Company made a prepayment to White Oak, with respect to our obligations under the loan and security agreement with White Oak, in the amount of $5.0 million from the Company’s restricted account. Additionally, the outstanding obligations under the White Oak loan will become due on or before August 17, 2016. As of December 31, 2015, the debt was classified as a short-term liability. In connection with this arrangement, White Oak also requires that the Company’s investment in a Certificate of Deposit of $5.0 million , along with investments in Luna Innovations, Inc., to be restricted subject to lenders’ control. As of December 31, 2015, the Company’s cash, cash equivalents, short-term investments and restricted cash balances were $28.0 million . The Company anticipates that its existing available capital resources as of December 31, 2015 and the estimated amounts received through the sale of its products and services will not be sufficient to meet its anticipated cash requirements for the next twelve months. These factors raise substantial doubt about the Company’s ability to continue as a going concern. The Company will need to obtain sufficient additional funding to satisfy its current and longer term liquidity requirements and may attempt to do so at any time by, for example, selling equity or debt securities, licensing core or non-core intellectual property assets, entering into future research and development funding arrangements, refinancing or restructuring existing debt arrangements or entering into a credit facility in order to meet its continuing cash needs. The Company cannot guarantee that future equity or debt financing or credit facilities will be available in amounts or on terms acceptable to it, if at all, that it will achieve or maintain compliance with debt covenants, that it will be able to license core or non-core intellectual property assets or enter into future research and development funding arrangements. If such financing, licensing, funding or credit arrangements do not meet the Company’s current and longer term needs, the Company may be required to extend its existing cash and liquidity by adopting additional cost-cutting measures, including reductions in its work force, reducing the scope of, delaying or eliminating some or all of its planned research, development and commercialization activities and/or reducing marketing, customer support or other resources devoted to the Company’s products. Any of these factors could harm the Company’s financial condition. Failure to raise additional funding or manage spending may adversely impact the Company’s ability to achieve its long term intended business objectives. The Company will continue to evaluate its financial condition based upon changing future economic conditions, and will consider the implementation of additional cost reductions if and as circumstances warrant. The accompanying consolidated financial statements do not include any adjustments that might result from the outcome of this uncertainty. Reclassification of Prior Period Balances Certain reclassifications have been made to prior period amounts to conform to the current-year presentation.Such reclassifications did not have a material impact on the Company’s results of operations or financial position.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The Company has prepared the accompanying consolidated financial statements in accordance with generally accepted accounting principles in the United States of America (“GAAP”). The Company’s fiscal year ends on December 31. The consolidated financial statements include the accounts of the Company and its subsidiaries. All significant intercompany accounts and transactions have been eliminated. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Significant estimates relate to the recognition of revenue, the evaluation of customer credit risk, the valuation of investments, inventory valuations, warrant valuations, the determination of impairment of assets, stock-based compensation, loss contingencies and the valuation of our deferred tax assets, among others. Actual results could differ from those estimates. Reverse Split of Common Stock On May 12, 2015, at the Annual Meeting of Stockholders of the Company, the stockholders approved a series of alternate amendments to the Company’s Certificate of Incorporation (the "Certificate") to effect, at the discretion of the Company’s Board of Directors (the "Board"), a reverse stock split of the Company’s common stock whereby each outstanding four, six, eight or ten shares would be combined into one share of common stock and a proportional reduction in the number of authorized shares of common stock. On September 18, 2015, the Board approved a reverse stock split of the Company’s outstanding shares of common stock at a ratio of one-for-ten and the related amendment to the Certificate providing for the combination of each outstanding ten shares of Company common stock into one share of Company common stock. The amendment to the Certificate was filed with the Secretary of State of the State of Delaware on September 22, 2015, decreasing the Company’s authorized common stock from 300,000,000 to 30,000,000 . Historical share information presented in the accompanying financial statements has been retroactively adjusted to reflect this reverse stock split. Revenue Recognition The Company’s revenues are primarily derived from the sale of the Sensei System and the Magellan System and the associated catheters as well as the sale of customer service contracts, which includes post-contract customer support (“PCS”). The Company sells its products directly to customers as well as through distributors. Under the Company’s revenue recognition policy, revenues are recognized when persuasive evidence of an arrangement exists, title and risk of loss has passed, delivery to the customer has occurred or the services have been fully rendered, the sales price is fixed or determinable and collectability is reasonably assured. • Persuasive Evidence of an Arrangement . Persuasive evidence of an arrangement for sales of systems is generally determined by a sales contract signed and dated by both the customer and the Company, including approved terms and conditions or the receipt of an approved purchase order. Evidence of an arrangement for the sale of disposable products is determined through an approved purchase order from the customer. Evidence of an arrangement for the sale of customer service is determined through either a signed sales contract or an approved purchase order from the customer. Sales are generally not subject to any performance, cancellation, termination or return rights. • Delivery . • Systems and Disposable Products. Typically, ownership of systems, catheters and other disposable products passes to customers upon shipment, at which time delivery is deemed to be complete. • Customer Service Revenue. The Company recognizes customer service revenue from the sale of its PCS contracts which includes planned and corrective maintenance services, software updates, bug fixes, and warranty. Revenue from customer services, whether sold individually or as a separate unit of accounting in a multi-element arrangement, is deferred and amortized over the service period, which is typically one year. • Multiple-element Arrangements. It is common for the sale of Sensei and Magellan Systems to include multiple elements which have standalone value and qualify as separate units of accounting. These elements commonly include the sale of the system and a product maintenance plan, in addition to installation of the system and initial training. Less commonly, these elements may include the sale of certain disposable products or other elements. For multiple-element arrangements revenue is allocated to each element based on their relative selling prices. Relative selling prices are based first on vendor specified objective evidence (“VSOE”), then on third-party evidence of selling price (“TPE”) when VSOE does not exist, and then on management’s best estimate of the selling price (“ESP”) when VSOE and TPE do not exist. Because the Company has neither VSOE nor TPE for its system, the allocation of revenue is based on ESP for the systems sold. The objective of ESP is to determine the price at which the Company would transact a sale, had the product been sold on a stand-alone basis. The Company determines ESP for its systems by considering multiple factors, including, but not limited to, features and functionality of the system, geographies, type of customer, and market conditions. The Company regularly reviews ESP and maintains internal controls over the establishment and updates of these estimates. • Sales Price Fixed or Determinable. The Company assesses whether the sales price is fixed or determinable at the time of the transaction. Sales prices are documented in the executed sales contract or purchase order received prior to shipment The Company’s standard terms do not allow for contingencies, such as trial or evaluation periods, refundable orders, or extended payment terms payments contingent upon the customer obtaining financing or other contingencies which would impact the customer’s obligation. In situations where these or other contingencies are included, all related revenue is deferred until the contingency is resolved. In the third quarter of 2012, the Company began shipping systems under a limited commercial evaluation program to allow certain strategic accounts to install and utilize systems for a limited trial period of three to six months while the purchase opportunity is being evaluated by the hospital. Systems under this program remain the property of the Company and are recorded in inventory and a sale only occurs upon the issuance of a purchase order from the customer. • Collectability. The Company assesses whether collection is probable based on a number of factors, including the customer’s past transaction history and credit worthiness. If collection of the sales price is not deemed probable, the revenue is deferred and recognized at the time collection becomes probable, which is usually upon receipt of cash. The Company’s sales contracts generally do not allow the customer the right of cancellation, refund or return, except as provided under the Company’s standard warranty. If such rights were allowed, all related revenues would be deferred until such rights expired. Significant management judgments and estimates are made in connection with the determination of revenue to be recognized and the period in which it is recognized. If different judgments and estimates were utilized, the amount of revenue to be recognized and the period in which it is recognized could differ materially from the amounts reported. Concentration of Credit Risk and Other Risks and Uncertainties Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents, short-term investments and accounts receivable. Cash and cash equivalents are deposited in demand and money market accounts at one financial institution. At times, such deposits may be in excess of insured limits. The Company has not experienced any losses on its deposits of cash and cash equivalents. The Company had four customers who constituted 19% , 18% , 12% and 12% , respectively of the Company’s net accounts receivable at December 31, 2015. The Company had four customers who constituted 26% , 14% , 12% , and 12% , respectively of the Company’s net accounts receivable at December 31, 2014. The Company carefully monitors the creditworthiness of potential customers. As of December 31, 2015, the Company has not experienced any significant losses on its accounts receivable. Two customers accounted for 11% and 11% , respectively of total revenues for fiscal year 2015. Two customers accounted for 13% and 10% , respectively of total revenues for fiscal year 2014. One customer accounted for 10% of total revenues for fiscal year 2013. Most of the products developed by the Company require clearance from the U.S. Food and Drug Administration (“FDA”) or corresponding approval by foreign regulatory agencies prior to commercial sales. These clearances and approvals are required for both the Sensei and Magellan Systems and all related catheters and accessories: Sensei: The Company received CE Mark approval to market its Sensei System in Europe in the fourth quarter of 2006 and received CE Mark approval to market its Artisan ® Control Catheter in Europe in May 2007. The Company received FDA clearance for the marketing of its Sensei System and Artisan Extend catheters for manipulation, positioning and control of certain mapping catheters during electrophysiology (“EP”) procedures in the United States in May 2007. Magellan: At the current time the Company has received clearance and approval for the Magellan System and the Magellan 6Fr, 9Fr and 10Fr Robotic Catheters and related accessories in various territories. The Company received CE Mark approval for its Magellan System in July 2011 and received CE Mark approval for the Magellan 9Fr Robotic Catheter and related accessories in October 2011. The Magellan 6Fr Robotic Catheter received CE Mark approval in October 2014, while the Magellan 10Fr Robotic Catheter received CE Mark approval in April 2015. The Company received FDA clearance for marketing its Magellan System, including the Magellan 9Fr Robotic Catheter and accessories in June 2012, the Magellan 6Fr Robotic Catheter in February 2014, and the Magellan 10Fr Robotic Catheter in July 2015. The FDA clearances and CE Mark approvals enable the company to initiate use of all Magellan Systems and catheters with its customers in the United States, the European Union and certain other geographies. However, there can be no assurance that current products or any new products the Company develops in the future will receive the clearances or approvals necessary to allow the Company to market those products in certain desirable markets. If the Company is denied clearance or approvals or clearance or approvals are delayed, it could have a material adverse impact on the Company. The medical device industry is characterized by frequent and extensive litigation and administrative proceedings over patent and other intellectual property rights. Whether a product infringes a patent involves complex legal and factual issues, the determination of which is often difficult to predict, and the outcome may be uncertain until the court has entered final judgment and all appeals are exhausted. The Company’s competitors may assert, and have asserted in the past, that the Company’s products or the use of the Company’s products are covered by United States or foreign patents held by them. This risk is heightened due to the numerous issued and pending patents relating to the use of catheter-based procedures in the medical technology field. Loss Contingencies The Company evaluates potential loss contingencies as circumstances dictate. Should a specific loss contingency meet the definition of a liability under authoritative accounting guidance, the Company would record a loss and a liability. As of December 31, 2015, the Company had not recorded any loss contingencies as liabilities. However, if estimates and assumptions change in the future, the Company may record charges to its financial statements. This could materially impact its operating results and financial position. Foreign Currency Assets and liabilities of non-U.S. subsidiaries that operate in a local currency environment, where that local currency is the functional currency, are translated at current exchange rates as of the end of the accounting period. The related revenues and expenses are translated at average exchange rates in effect during the period. Net exchange gains and losses resulting from translation are excluded from income and are recorded as part of accumulated other comprehensive income. Transactions denominated in a foreign currency are revalued at the current exchange rate at the transaction date and any related gains and losses are reflected in investment and other income, net in the consolidated statements of income. Fair Value Measurements GAAP defines fair value as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, authoritative guidance establishes a three-tier value hierarchy, which prioritizes the inputs used in measuring fair value as follows: • Level 1 Inputs Quoted prices (unadjusted) in active markets for identical assets or liabilities. • Level 2 Inputs Inputs other than quoted prices in active markets that are observable either directly or indirectly. • Level 3 Inputs Unobservable inputs in which there is little or no market data, which require the Company to develop its own assumptions. This hierarchy requires the use of observable market data when available and to minimize the use of unobservable inputs when determining fair value. Fair Value of Financial Instruments Carrying amounts of certain of the Company’s financial instruments, including cash and cash equivalents, accounts receivable, and accounts payable approximate fair value due to their short maturities. Cash and Cash Equivalents, and Restricted Cash The Company considers all highly liquid investments with maturities of three months or less at the time of purchase to be cash equivalents. Cash and cash equivalents, and restricted cash include money market funds and various deposit accounts, which are readily convertible to cash and are stated at cost, which approximates market. Pursuant to the Company’s loan and security agreement executed in 2013, the Company is obligated to maintain $5.0 million of restricted cash subject to lenders’ control. The Company also maintains $750,000 in restricted cash as collateral to obtain a letter of credit used as a lease security for its new office in San Jose, California. Short-Term Investments Available-for-sale investments. The Company determines the appropriate classification of investments at the time of purchase and evaluates such classification as of each balance sheet date. The Company classifies all investments with maturities greater than three months at the time of purchase as short-term investments as they are subject to use within one year in current operations. The Company makes investments based upon specific guidelines approved by its board of directors with a view to liquidity and capital preservation and regularly reviews its investments for performance. As of December 31, 2015, all of the Company’s investments have been classified as available-for-sale and are carried on the balance sheet at fair value with the unrealized gains and losses, if any, included in other comprehensive income within stockholders’ equity. Any unrealized losses which are determined to be other than temporary are included in earnings. Other-than-temporary impairment. The Company periodically evaluates its investments for impairment. In the event that the carrying value of an investment exceeds its fair value and the decline in fair value is determined to be other than temporary, an impairment charge is recorded and a new cost basis for the investment is established. The primarily differentiating factors the Company considered to determine whether a decline in value is other than temporary are our intent and ability to retain its investment in the issuer for a period of time sufficient to allow for any anticipated recovery in market value, the length of the time and the extent to which the market value of the investment has been less than cost, the financial condition and near-term prospects of the issuer. Given the current market conditions, these judgments could prove to be wrong, and companies with relatively high credit ratings and solid financial conditions may not be able to fulfill their obligations. During the year ended December 31, 2013, the Company recorded pre-tax losses of $0.6 million related to a decline in the value of our investment in Luna Innovations Incorporated common stock that the Company concluded were other-than-temporary. No impairment loss were recorded during the years ended December 31, 2015 and 2014. As of December 31, 2015 and 2014, net unrealized gains (loss) on investments of $(0.4) million and $0.02 million , net of tax, respectively, were included in accumulated other comprehensive income (loss). Significant management judgment is required in determining whether an other-than-temporary decline in the fair value of an investment exists. Changes in the Company’s assessment of the valuation of investments could materially impact future operating results and financial position. Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable primarily include amount due from hospitals and distributors. The Company establishes allowances for doubtful accounts based on a review of the credit profiles of customers, contractual terms and conditions, current economic trends and historical collection experience. The allowance for doubtful accounts is reassessed each period based on management’s assessment of historical expected net collections and other collection indicators. Inventories Inventories, which includes material, labor and overhead costs, are stated at standard cost, which approximates actual cost, determined on a first-in, first-out basis, and not in excess of net realizable value. The cost basis of the Company’s inventory is reduced for any products that are considered excessive or obsolete based upon assumptions about future demand and market conditions. In the event actual demand for our inventory differs from our best estimates or we fail to receive necessary regulatory approvals, further reduction in our basis of inventory may become necessary. Property and Equipment, Net Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation of property and equipment is computed using the straight-line method over their estimated useful lives of two to five years. Leasehold improvements are amortized on a straight-line basis over the lesser of their useful life or the term of the lease. Depreciation expense was $1.0 million , $2.6 million and $2.9 million for the years ended December 31, 2015, 2014 and 2013, respectively. Impairment of Long-Lived Assets The Company evaluates the recoverability of its long-lived assets in accordance with authoritative accounting guidance. When events or changes in circumstances indicate that the carrying value of long-lived assets may not be recoverable, the Company recognizes such impairment if the net book value of such assets exceeds the future undiscounted cash flows attributable to such assets. Should an impairment exist, the impairment loss would be measured based on the excess carrying value of the asset over the asset’s fair value or discounted estimates of future cash flows attributable to the assets. As of December 31, 2015, the Company had $2.3 million of property and equipment, net. If estimates or the related assumptions change in the future, the Company may record impairment charges to reduce the carrying value of certain groups of these assets. Changes in the valuation of long-lived assets could materially impact the Company’s operating results and financial position. Advertising Expense The Company expenses advertising costs as incurred. Advertising costs are recorded in general, sales and marketing expenses within the accompanying consolidated statements of operations was $0.6 million and $0.7 million for fiscal year 2015 and 2014, respectively and was immaterial for fiscal year 2013. Stock-Based Compensation The Company accounts for share-based compensation plan in accordance with the provisions of the Financial Accounting Standards Board (“FASB”) Accounting Standard Codification ("ASC") No. 718-10-30, Stock Compensation Initial Measurement, which requires the measurement and recognition of compensation expense for all stock-based awards made to employees and directors including employee stock options, restricted stock units (“RSUs”), performance stock units (“PSUs”) and employee stock purchases under our Employee Stock Purchase Plan (“ESPP”) based on estimated fair values and recognizes stock-based compensation expense, net of estimated forfeitures, on a ratable basis over the requisite service period. The Company estimates the fair value of stock options granted using the Black-Scholes-Merton (“BSM”) option valuation model. The BSM option valuation model is used to determine the fair value of stock-based awards with the following assumptions • Expected Volatility . The Company’s estimate of volatility is based on the historical volatilities of its stock price. • Expected Term . The Company estimates the expected term based on its historical settlement experience related to vesting and contractual terms while giving consideration to awards that have life cycles less than the contractual terms and vesting schedules in accordance with authoritative guidance. • Risk-Free Interest Rate. The risk-free interest rate that the Company uses in the BSM option valuation model is the implied yield in effect at the time of option grant based on U.S. Treasury zero-coupon issues with a remaining term equivalent to the expected term of its option grants. For ESPP grants, the Company uses the 6-month Constant Maturity Treasury rate. • Dividend Yield. The Company has never paid any cash dividends on its common stock and it does not anticipate paying any cash dividends in the foreseeable future. Consequently, the Company uses a dividend yield of zero in the BSM option valuation model. The Company measures the fair value of RSUs and PSUs using the closing stock price of a share of the Company’s common stock on the grant date. In addition, the Company also estimates a forfeiture rate for its stock options and RSUs. The Company estimates its forfeiture rate based on an analysis of its actual forfeitures based on actual forfeiture experience, analysis of employee turnover behavior and other factors. The impact from any forfeiture rate adjustment would be recognized in full in the period of adjustment and, if the actual number of future forfeitures differs from its estimates, the Company might be required to record adjustments to its stock-based compensation in future periods. For PSUs, the Company recognizes stock-based compensation expense based on the probable outcome that the performance condition will be achieved. Research and Development Research and development costs are charged to expense as incurred. Research and development costs include, but are not limited to, payroll and other personnel expenses, prototype materials, laboratory supplies, and consulting costs. Income Taxes The Company accounts for income taxes using the liability method whereby deferred tax asset and liability account balances are determined based on differences between financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. Valuation allowances are established to reduce deferred tax assets when management estimates, based on available objective evidence, that it is more likely than not that the benefit will not be realized for the deferred tax assets. The Company accounts for uncertainty in income taxes using a two-step approach to recognizing and measuring uncertain tax positions. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained on audit, including resolution of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount that is more than 50% likely of being realized upon settlement. The Company recognizes interest and penalties related to unrecognized tax benefits as a component of income tax expense. As of December 31, 2015, the Company has no accrued interest or penalties related to uncertain tax positions. The Company does not anticipate that total unrecognized tax benefits will significantly change due to the settlement of audits and the expiration of statute of limitations periods in 2015. Comprehensive Loss The Company follows the accounting standards for the reporting and presentation of comprehensive income (loss) and its components. Comprehensive loss includes all changes in stockholders’ equity during a period from non-owner sources. Comprehensive loss for each of the years ended December 31, 2015, 2014 and 2013 was equal to net loss adjusted for unrealized gains and losses on investments, reclassifications of realized gains and losses on investments to other income (expense) and foreign currency translation adjustments. Computation of Net Loss Per Share Basic net loss per 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 share is computed using the weighted-average number of shares and diluted potential shares outstanding during the period. Dilutive potential shares are excluded when the effect would be to reduce a net loss per share. The Company’s dilutive potential shares primarily consists of outstanding common stock options, warrants, estimated shares to be issued under the Company’s employee stock purchase plan and unvested restricted stock, which have not been included in the computation of diluted net loss per share for all periods as the result would be anti-dilutive. Recent Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes the revenue recognition requirements in ASC 605, Revenue Recognition . ASU 2014-09 is based on the principle that revenue is recognized to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. This new guidance is effective for annual reporting periods beginning after December 15, 2016, including interim periods within those fiscal years. Early adoption is not permitted. The Company is currently assessing the impact of the adoption of ASU 2014-09 on its consolidated financial statements. In August 2014, the FASB issued ASU No. 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 205-40 ): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. The ASU provides guidance on determining when and how to disclose going-concern uncertainties in the financial statements. The new standard requires management to perform interim and annual assessments of an entity’s ability to continue as a going concern within one year of the date the financial statements are issued. An entity must provide certain disclosures if “conditions or events raise substantial doubt about the entity’s ability to continue as a going concern.” The ASU applies to all entities and is effective for annual periods ending after December 15, 2016, and interim periods thereafter, with early adoption permitted. The Company has been assessing the going concern issue since 2010 on an interim and annual basis and will continue to assess whether the financial conditions based on this new guidance have an impact on the Company’s consolidated financial statements or footnotes. In January 2015, the FASB issued ASU 2015-01, Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items. This ASU eliminates from GAAP the concept of extraordinary items, and is effective for annual periods beginning after December 15, 2015, with early adoption permitted. The change primarily involves presentation and disclosure and, therefore, is not expected to have a material impact on the Company’s financial condition, results of operations or cash flows. In April 2015, the FASB issued ASU 2015-03, Interest-Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Cost , which changes the presentation of debt issuance costs in financial statements. Under the ASU, an entity presents costs in the balance sheet as a direct deduction from the related debt liability rather than as an asset. Amortization of the costs is reported as interest expense. Under current guidance, an entity reports debt issuance costs in the balance sheet as deferred charges (i.e. as an asset). For public companies, the ASU is effective for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years, with early adoption permitted. Entities would apply the new guidance retrospectively to all prior periods. The Company is currently assessing the impact of the adoption of ASU 2015-03 on its consolidated financial statements. In July 2015, the FASB issued ASU 2015-11, Simplifying the Measurement of Inventory . Under this ASU, inventory will be measured at the “lower of cost and net realizable value” and options that currently exist for “market value” will be eliminated. The ASU defines net realizable value as the “estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation.” No other changes were made to the current guidance on inventory measurement. ASU 2015-11 is effective for interim and annual periods beginning after December 15, 2016. Early adoption is permitted and should be applied prospectively. The Company does not expect the adoption of this accounting standard update to impact its consolidated financial statements. In November 2015, the FASB issued ASU 2015-17, Balance Sheet Classification of Deferred Taxes , which simplifies the presentation of deferred income taxes. This ASU amends the existing guidance to require presentation of deferred tax assets and liabilities as noncurrent within a classified statement of financial position. The Company early adopted ASU 2015-17 effective December 2015 on a prospective basis. The adoption did not have an impact on the financial statements of the Company. In February 2016, the FASB issued ASU 2016-02, Leases , which require a lessee to recognize lease assets and liabilities on the balance sheet for all arrangements with terms longer than 12 months. Lessor accounting remains largely consistent with existing U.S. GAAP. The new standard takes effect in 2019 for public business entities and 2020 for all other entities. The Company is currently assessing the impact of the adoption of ASU 2016-02 on its consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting . ASU 2016-09 requires among other things that all excess tax benefits and tax deficiencies (including tax benefits of dividends on share-based payment awards) to be recognized as income tax expense or benefit in the income statement. The tax effects of exercised or veste

Fair Value of Assets and Liabil

Fair Value of Assets and Liabilities	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value of Assets and Liabilities	Fair Value of Assets and Liabilities The Company’s financial instruments consist principally of cash and cash equivalents, short-term investments, accounts receivable, accounts payable and short-term and long-term debt. Cash and cash equivalents, short-term investments and accounts receivable, net of allowance, are reported at their respective fair values on the Consolidated Balance Sheets. Short-term and long-term debt are reported at their amortized cost on our Consolidated Balance Sheets. The remaining financial instruments are reported on the Consolidated Balance Sheets at amounts that approximate current fair values. The amortized cost and fair value of assets, along with gross unrealized gains and losses, were as follows (in thousands): Cash, Cash Equivalents, Short-term Investments and Restricted Cash Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Balance Sheet Classification Cash and cash Equivalents Short-term Investments Restricted Cash December 31, 2015: Cash $ 1,408 $ — $ — $ 1,408 $ 1,408 $ — $ — Money market funds 25,080 — — 25,080 18,967 — 6,113 Corporate equity securities 1,572 — (71 ) 1,501 — 1,501 — $ 28,060 $ — $ (71 ) $ 27,989 $ 20,375 $ 1,501 $ 6,113 December 31, 2014: Cash $ 3,586 $ — $ — $ 3,586 $ 3,586 $ — $ — Money market funds 26,318 — — 26,318 20,942 — 5,376 Corporate equity securities 1,572 401 — 1,973 — 1,973 — $ 31,476 $ 401 $ — $ 31,877 $ 24,528 $ 1,973 $ 5,376 Gross unrealized losses at December 31, 2015 include our investment in Luna Innovations (“Luna”) equity securities which have been in a gross unrealized loss for less than 12 months. Fair Value Measurements The fair value hierarchy of the Company’s assets and liabilities that are measured at fair value, by level, is as follows (in thousands): Fair Value Measurements Using Quoted Prices in Active Markets for Identical Assets (Level 1 Inputs) Significant other Observable Inputs (Level 2 Inputs) Unobservable Inputs (Level 3 Inputs) Total December 31, 2015: Assets: Money market funds $ 25,080 $ — $ — $ 25,080 Corporate equity securities 1,501 — — 1,501 $ 26,581 $ — $ — $ 26,581 December 31, 2014: Money market funds $ 26,318 $ — $ — $ 26,318 Corporate equity securities 1,973 — — 1,973 $ 28,291 $ — $ — $ 28,291 Investment instruments valued using Level 1 inputs include the Company’s money market securities and certain of the corporate equity securities which were obtained by the Company as part of the Luna litigation settlement. The Company periodically assesses whether significant facts and circumstance have arisen to indicate that an impairment, which is other than temporary, of the fair value of any underlying investment has occurred. In 2013, the Company determined that there was an other than temporary impairment of its investment in Luna Innovations, or Luna, which the Company received as part of a litigation settlement entered into in January 2010 and had recorded as an available for sale corporate equity security. As such, the Company wrote down the value of that investment and recorded a loss of $0.6 million in other expense in the consolidated statement of operations. No other investments have been in an unrealized loss position for longer than twelve months. The changes in Level 3 liabilities measured at fair value on a recurring basis was as follow (in thousands): Level 3 Input for Year Ended December 31, 2015 (In thousands) Balance at December 31, 2014 $ — Additions at March 11, 2015 (14,776 ) Change in fair value of warrant liability (2,993 ) Reclassification to additional paid-in capital 17,769 Balance at December 31, 2015 $ — Warrant Liability In connection with the issuance of Series A convertible preferred stock on March 11, 2015, the Company also issued Series E Warrants to the participating investors to purchase an aggregate of 5,384,600 shares of common stock with an exercise period of two years from the date of issuance. On the date of issuance, the exercise price for the Series E Warrants was the lesser of $9.75 per share or a 50% premium on the per share trailing volume weighted average share price of the common stock on NASDAQ for the ten trading days ending on dates specified in the form of Series E Warrants filed with the SEC. The Series E Warrants were not exercisable until receipt of stockholder approval to among other things increase the number of authorized shares of common stock of the Company. The proposal relating to such approval was presented and received the stockholder approval at the 2015 Annual Meeting of Stockholders of the Company held on May 12, 2015 (the “Requisite Stockholder Approval”). As a result of the contingency which was deemed outside the Company’s control, such Series E Warrants did not originally meet the criteria for classification as equity under ASC 815. As such, the Company classified the Series E Warrants as current liabilities at fair value upon issuance of $14.8 million . The Company used a third party valuation that utilized the Monte Carlo simulation model to estimate the fair value of the Series A convertible preferred stock and Series E Warrants. The valuation used a simulation of the Company’s periodic stock price, expected volatility of the price, adjusted for conversion price, and the remaining contractual term of the warrants. The Series E Warrants were subject to re-measurement at each balance sheet date, with any change in fair value recognized as warrant expense, a component of other income (expense) reflected within the statement of operations. The Company recorded the change in fair value of $3.0 million on the consolidated statements of operations for the year ended December 31, 2015. Upon receipt of Requisite Stockholder Approval, all criteria for the Series E Warrants to be classified as equity were met. Using the BSM model with an exercise price of $9.75 per share for the Series E Warrants, the Company revalued the warrants and reclassified the warrant liability of $17.8 million , representing the fair value of the Company’s warrant liability as of the Requisite Stockholder Approval date, to additional paid-in capital. See Note 10 for further information regarding the Company’s 2015 private placement of Series A convertible preferred stock and Series E Warrants. All of the Series E Warrants are currently issued and outstanding as of December 31, 2015. Long-term Debt The fair value of the Company’s long-term debt was estimated to be $35.1 million as of December 31, 2015 based on an internal valuation model that utilized the then-current rates available to the Company for debt of a similar term and remaining maturity, which constitutes Level 2 inputs under the fair value hierarchy. Considerable judgment is required in interpreting market data to develop estimates of fair value. Accordingly, the fair value estimate presented herein is not necessarily indicative of the amount that the Company or holders of the instruments could realize in a current market exchange. The use of different assumptions and/or estimation methodologies may have a material effect on the estimated fair value. See Note 8 for further information regarding the Company’s long-term debt.

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Components	Balance Sheet Components Allowance for Doubtful Accounts (in thousands) December 31, 2015 2014 2013 Balance at Beginning of the Year $ — $ 554 $ 554 Additions Charges to Cost and Expenses 49 21 — Write-offs (26 ) (475 ) — Balance Before Recoveries $ 23 $ 100 $ 554 Less: Recoveries — (100 ) — Balance at the End of the Year $ 23 $ — $ 554 Inventories, net (in thousands) December 31, 2015 2014 Raw materials $ 2,613 $ 4,996 Work in process 3,575 4,571 Finished goods 2,471 1,925 Inventories $ 8,659 $ 11,492 Property and equipment, net (in thousands) December 31, 2015 2014 Furniture and leasehold improvements $ 11,329 $ 11,455 Laboratory equipment 12,158 11,374 Computer equipment and software 2,956 2,911 26,443 25,740 Less: Accumulated depreciation and amortization (24,118 ) (23,412 ) Property and equipment, net $ 2,325 $ 2,328 Accrued liabilities (in thousands) December 31, 2015 2014 Accrued restructuring $ 1,581 $ — Accrued salaries, commission, bonus and benefits 1,094 2,835 Tax accruals 333 274 Accrued royalties 330 594 Accrued legal and other professional fees 228 169 Clinical related accruals 60 394 Other accrued expenses 487 676 Total $ 4,113 $ 4,942

Agreements with Intuitive Surgi

Agreements with Intuitive Surgical	12 Months Ended
	Dec. 31, 2015
Updated License Agreement And Stock Sell Agreement Textual [Abstract]
Agreements with Intuitive Surgical	Agreements with Intuitive In October 2012, the Company signed an updated license agreement with Intuitive Surgical Operations, Inc. and Intuitive Surgical, Inc. (collectively, “Intuitive”), under which Intuitive paid the Company a $20.0 million licensing fee, and entered into a stock purchase agreement to buy 529,101 shares of the Company’s common stock for an aggregate purchase price of $10.0 million . The amendment of the license agreement updated the co-exclusive cross license agreement signed by the companies in 2005. Under the terms of the amended agreement, Intuitive’s co-exclusive rights extended to include intellectual property rights filed or conceived by the Company in the non-vascular space subsequent to the original 2005 agreement through October 26, 2015. The Company retained the right to use its intellectual property for all clinical applications, both vascular and non-vascular. The Company previously concluded that the value associated with patents filed or conceived in the three years subsequent to the amendment was de minimis and therefore the $20.0 million upfront payment for the licensing of intellectual property was recognized in the statement of operations in fiscal year 2012. The $10.0 million associated with the stock purchase agreement was recorded to common stock and additional paid-in capital on the balance sheet in 2012. The term of the intellectual property capture period expired on October 26, 2015. The cross-licenses and royalty obligations remain in effect. The Company has minimum royalty obligations of $0.2 million per year under the terms of its cross license agreement with Intuitive Surgical. For fiscal years 2015, 2014 and 2013, the Company incurred cost in the amount of $0.2 million , $0.3 million and $0.2 million , respectively related to the royalty obligations to Intuitive Surgical.

Agreements with Philips

Agreements with Philips	12 Months Ended
	Dec. 31, 2015
Agreements With Philips Additional Textual [Abstract]
Agreements with Philips	Agreements with Philips In February 2011, the Company entered, directly and through a wholly-owned subsidiary, into various agreements with Koninklijke Philips Electronics N.V. (“Philips”) to allow Philips to develop and commercialize the non-robotic applications of the Company’s Fiber Optic Shape Sensing and Localization (“FOSSL”) technology (the “FOSSL Agreement”). Under the terms of the FOSSL Agreement, Philips obtained exclusive right to develop and commercialize the FOSSL technology in the non-robotic vascular, endoluminal and orthopedic fields. Philips also received non-exclusive rights in other non-robotic medical device fields, but not to any multi-degree of freedom robotic applications. Under the terms of the FOSSL Agreement, if Philips did not meet certain specified commercialization obligations, the Company reserved rights to re-acquire the licenses granted to Philips for pre-determined payments, which payments in the aggregate would be greater than the upfront payment amounts received by the Company from Philips in connection with the agreements related to the FOSSL technology. The FOSSL Agreement also contains customary representations, warranties and indemnification provisions by each party. Each party may terminate the agreement for material breach by the other party. Philips also has the right to terminate the agreement and its rights under the agreement if the Company is acquired by a competitor of the relevant business unit of Philips. In February 2011, the Company amended its extended joint development agreement with Philips (the “JDA”), increasing the amount of funding provided by Philips for the development of the Vascular System and potentially extending and increasing certain royalty fees to be paid to Philips based on sales of the Vascular System, subject to caps based on the amounts Philips contributed to the development of the system. Under the amendment, the Company was eligible to receive up to an additional $78.0 million in future payments associated with the successful commercialization by Philips or its collaborators of products containing FOSSL technology. Approximately two-thirds of these potential future payments could arise from Philips’ sublicensing the FOSSL technology and approximately one-third of the potential future payments were based on Philips’ royalty obligations on its sales of products containing the FOSSL technology. The Company would receive less than half of Philips’ proceeds for its sublicensing FOSSL technology if and following Philips entering into an applicable sublicensing transaction. Philips’ FOSSL-related royalty obligations were to be calculated on a consistent annual basis between 2014 and 2020 in any year only to the extent that Philips achieved a substantial number of commercial placements of FOSSL-enabled products in the calendar year. The Company’s royalty obligations under the JDA provided for the payment of royalties to Philips through October 2017 . In August 2015, the Company and Philips entered into an amendment to the FOSSL Agreement and the JDA (the “Amended Agreements”), extinguishing the Company’s rights to re-acquire the licenses in the non-robotic vascular, endoluminal and orthopedic fields in FOSSL technology in exchange for a reduction of all royalties owed or due between the parties of fifty percent (50%) . Under the Amended Agreements, the Company’s royalty obligations to Philips based on sales of the Vascular Systems were reduced by fifty percent (50%) . The Company’s royalty obligations continue through October 2017. Similarly, Philips royalty obligations were also all reduced by fifty percent (50%) , including but not limited to all royalty obligations due under the Amended Agreements that arise from Philips’ sublicensing the FOSSL technology. Under the Amended Agreements, Philips’ FOSSL-related royalty obligations will be calculated on a consistent basis for the royalty period starting with the first calendar year after the first sale by Philips of a FOSSL system and ending with the sixth calendar year after the first sale, but only to the extent that Philips achieves certain number of commercial placements of FOSSL-enabled products during the royalty period. The Amended Agreements contain customary representations, warranties and indemnification provisions by each party. Each party may terminate the agreements for material breach by the other party. Philips also has the right to terminate the agreement and its rights under the agreement if the Company is acquired by a competitor of the relevant business unit of Philips. Under the terms of the Amended Agreements, the Company continues to have no minimum obligation with Philips, and the royalty obligation is based on per unit sales of the Magellan Systems and vascular catheters. For fiscal years 2015, 2014 and 2013, the Company incurred cost in the amount of $0.7 million , $1.2 million and $0.9 million , respectively related to the royalty obligations to Philips.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Leases The Company rents its office and laboratory facilities in Mountain View, California under an operating lease. On December 15, 2015, the Company entered into a Lease Termination Agreement with its landlord for the termination of the Company's existing lease in Mountain View, California. The Lease Termination is to become effective not earlier than June 1, 2016 but no later than August 31, 2016. Upon the effective date of the Lease Termination, the Company will be released from all of its obligations under the Existing lease, except for certain expenses and indemnification obligations as set forth in the Lease Termination. Concurrently, the Company entered into a lease agreement with LBA Realty Fund11-WBP VII, Inc. to rent 32,552 square feet of office and manufacturing space located in San Jose, California with a commencement date of June 1, 2016 but no later than August 1, 2016, and expiring in February 2027. The Company also leases approximately 3,300 square feet of office space in London, England under an operating lease of which ends in June 30, 2020 . As of December 31, 2015, the Company has exercised the option to exit the 3,300 square feet of office lease space in London, England in 2015 and incurred $0.1 million exit cost recorded on the consolidated statement of operations. On March 17, 2015, the Company signed a rental agreement with Regus Management (UK) limited to rent office space for our London office. Rent expense on a straight-line basis was as follows (in thousands): Years Ended December 31, 2015 2014 2013 Rent expense $ 2,782 $ 2,613 $ 2,310 At December 31, 2015, future minimum payments under the leases are as follows (in thousands): Years ended December 31, Future Minimum Lease Payments 2016 $ 1,728 2017 297 2018 610 2019 628 2020 647 Thereafter 4,443 Total $ 8,353 Warranties The Company generally provides one year of post-contract customer service on the sale of its systems. Post-contract customer service revenue is recognized ratably over the term of the service period and associated expenses are charged to cost of revenues as incurred. The Company provides a limited warranty on the sale of robotic systems and records a warranty reserve at the time of sale to cover the estimated warranty costs. The Company’s warranty obligation may be impacted by product failure rates, material usage and service costs associated with its warranty obligations. The Company periodically evaluates and adjusts the warranty reserve to the extent actual warranty expense differs from the original estimates. Movement in the warranty liability has not been significant for the years ended December 31, 2015 and 2014, respectively. Other Royalty Obligations The Company has minimum royalty obligations of $100,000 per year under a license agreement with Mitsubishi Electric Research Laboratories, Inc. which reduces to $55,000 per year if the license becomes non-exclusive. The royalty obligation expires in 2018 The Company incurred cost in the amount of $0.1 million related to the royalty obligations to Mitsubishi in each of the fiscal years 2015, 2014 and 2013. Indemnification The Company has agreements with each member of its Board of Directors, its President and Chief Executive Officer, its former President and its Interim Chief Financial Officer indemnifying them against liabilities arising from actions taken against the Company. To date, the Company has not incurred any material costs as a result of such indemnifications and has not accrued any liabilities related to such obligations in the accompanying financial statements. The Company has agreements with certain customers indemnifying them against liabilities arising from legal actions relating to the customer’s use of intellectual property owned by the Company. To date, the Company has not incurred any material costs as a result of such indemnifications and has not accrued any liabilities related to such obligations in the accompanying financial statements. Legal Proceedings Following the Company’s October 19, 2009 announcement that it would restate certain of its financial statements, a securities class action lawsuit was filed on October 23, 2009 in the United States District Court for the Northern District of California, naming the Company and certain of its now former officers. Curry v. Hansen Medical, Inc. et al., Case No. 9-5094. The complaint asserted claims for violation of Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 on behalf of a putative class of purchasers of Hansen stock between May 1, 2008 and October 18, 2009, inclusive, and alleged, among other things, that defendants made false and/or misleading statements and/or failed to make disclosures regarding the Company’s financial results and compliance with GAAP while improperly recognizing revenue; that these misstatements and/or nondisclosures resulted in overstatement of Company revenue and financial results and/or artificially inflated the Company’s stock price; and that following the Company’s October 19, 2009 announcement, the price of the Company’s stock declined. On November 4, 2009 and November 13, 2009, substantively identical complaints were filed in the Northern District of California by other purported Hansen stockholders asserting the same claims on behalf of the same putative class of Hansen stockholders. Livingstone v. Hansen Medical, Inc. et al., Case No. 9-5212 and Prenter v. Hansen Medical, Inc., et al., Case No. 9-5367. All three complaints sought certification as a class action and unspecified compensatory damages plus interest and attorneys’ fees. On December 22, 2009, two purported Hansen stockholders, Mina and Nader Farr, filed a joint application for appointment as lead plaintiffs and for consolidation of the three actions. On February 25, 2010, the Court issued an order granting Mina and Nader Farr’s application for appointment as lead plaintiffs and consolidating the three securities class actions. On July 15, 2010, the Court entered an order granting lead plaintiffs’ motion for leave to file a second amended complaint. Lead plaintiffs’ second amended complaint, in addition to alleging that shareholders suffered damages as a result of the decline in the Company’s stock price following the October 19, 2009 announcement, also alleged that shareholders suffered additional damages as the result of share price declines on July 28, 2009, July 31, 2009, January 8, 2009, July 6, 2009, and August 4, 2009, all of which lead plaintiffs alleged were caused by the disclosure of what they claim was previously misrepresented information. The Defendants filed their motion to dismiss the second amended complaint on October 13, 2010. The Court granted Defendants’ motion to dismiss with leave to amend on August 25, 2011. Plaintiffs’ third amended complaint was filed on October 18, 2011. Defendants filed their motions to dismiss on January 9, 2012. On August 10, 2012, the Court denied in part and granted in part Defendants’ motions to dismiss. On January 4, 2013, lead plaintiffs sought leave to amend their complaint to add certain of Hansen’s current and former directors and Hansen’s former auditor. Hansen filed an opposition to lead plaintiffs’ motion on February 11, 2013. On May 9, 2013, the parties entered a stipulation of settlement pursuant to which the plaintiffs would receive an aggregate of $8.5 million , $4.0 million of which would be funded in cash by the Company’s insurer and other sources. The Company would fund the remaining portion by issuing $4.25 million worth of the Company’s common stock, the number of shares to be determined based on the average closing price of the common stock for the 10 trading days preceding final Court approval of the settlement of the class action, and paying $250,000 in cash. The Company recorded a loss on litigation settlement of $4.5 million in its first quarter ended March 31, 2013. On December 5, 2013, the U.S. District Court for the Northern District of California granted final approval of a settlement. On December 19, 2013, the Company issued 229,854 shares, as determined by the average closing price of the Company’s common stock for the 10 trading days preceding final court approval of the settlement, which average was $18.49 per share.

Short-term and Long-term Debt

Short-term and Long-term Debt	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Short-term and Long-term Debt	Short-term and Long-term Debt Oxford Loan In December 2011, the Company entered into a $30.0 million loan and security agreement with Oxford Finance LLC and Silicon Valley Bank (the “Oxford Loan”). Under the loan agreement, the Company was obligated to pay interest only payments on the Oxford Loan through June 30, 2013, following which time the Oxford Loan required interest and principal payments through January 1, 2016. The Oxford Loan accrued interest at a stated rate of 9.45% and included an additional final interest payment of 3.95% of the original principal amount. The Oxford Loan provided for a prepayment option that allowed the Company to prepay all of the outstanding principal balance, subject to a pre-payment fee. In connection with the Oxford Loan, the Company issued warrants to purchase 66,079 shares of common stock. The warrants have an exercise price of $22.70 per share and expire in December 2018 . In August 2013, the Oxford Loan was fully repaid and extinguished under the loan agreement’s prepayment option. The Company paid a final interest balloon of $1.2 million plus accrued interest and a prepayment penalty. Following the repayment of the Oxford Loan, the Company recognized a loss on extinguishment of debt of $1.9 million , which included $0.9 million prepayment penalty, $0.5 million additional end of term payment and $0.5 million unamortized discount from warrants and issuance costs. White Oak Loan In July 2013, the Company executed a loan and security agreement with White Oak, as a lender and agent for several lenders. On August 23, 2013, the loan agreement was amended and restated and the loan was funded. The amended loan and security agreement provides for term loan debt financing of $33.0 million with a single principal balloon payment due at maturity on December 30, 2017 . Cash interest accrues at an 11.0% per annum rate and is payable quarterly. Additionally, a 3.0% per annum payment-in-kind accrues quarterly and is accretive to the principal amount owed under the agreement. Substantially all of the proceeds from the loan were used to fully repay and extinguish previous indebtedness. In connection with the loan, the Company incurred costs of approximately $1.5 million including payments to the lender agent totaling $0.7 million and the placement agent totaling $0.3 million which in aggregate are accounted for as debt issuance costs and amortized to interest expense over the life of the loan. Under the loan and security agreement, the Company is obligated to pay White Oak certain servicing, administration and monitoring fees of $32,000 annually. The Company may prepay all or a portion of the outstanding principal balance, subject to paying a prepayment fee of 3.5% of the principal amount of the loan prepaid if the prepayment is made on or before the third anniversary of the funding of the loan or 1.0% of the principal amount of the loan prepaid if the prepayment is made after the third anniversary and on or before the fourth anniversary of the funding of the loan. The Company is also required to make mandatory prepayments upon certain events of loss and certain dispositions of the Company’s assets as described in the loan and security agreement. For fiscal years 2015, 2014 and 2013, the Company recognized expense of $0.4 million , $0.4 million and 0.1 million , respectively, for the amortization of debt issuance costs related to the White Oak loan. The loan is collateralized by substantially all of the Company’s assets then owned or thereafter acquired, other than its intellectual property, and all proceeds and products thereof. Two of the Company’s wholly-owned subsidiaries, AorTx, Inc. and Hansen Medical International, Inc., have entered into agreements to guarantee the Company’s obligations under the loan and security agreement and have granted first priority security interests in their assets, excluding any of their intellectual property, to secure their guarantee obligations. Under the loan and security agreement, neither the Company nor AorTx, Inc. and Hansen Medical International, Inc. may grant a lien on any intellectual property to third parties. The Company additionally pledged to the lenders shares of each of its direct and indirect subsidiaries as collateral for the loan. Pursuant to the loan and security agreement, the Company is subject to certain affirmative and negative covenants and also to minimum liquidity requirements which require the Company to maintain $15.0 million in liquidity at all times, consisting of at least $13.0 million in cash, cash equivalents and investments, of which $5.0 million is required to be restricted subject to lenders’ control and the lesser of $2.0 million or 65% of eligible accounts receivable. Additionally, the Company is required to obtain an audit opinion from its independent certified public accountants on the annual financial statements that does not include an explanatory uncertainty paragraph raising substantial doubt about its ability to continue as a going concern or any qualification or exception as to the scope of such audit. The loan also limits the Company’s ability to (a) undergo certain change of control events; (b) convey, sell, lease, transfer, assign or otherwise dispose of any of its assets; (c) create, incur, assume, or be liable with respect to certain indebtedness, not including, among other items, subordinated debt; (d) grant liens; (e) pay dividends and make certain other restricted payments; (f) make certain investments; (g) make payments on any subordinated debt; or (h) enter into transactions with any of its affiliates outside of the ordinary course of business, or permit its subsidiaries to do the same. The Company is also required to make mandatory prepayments upon certain events of loss and certain dispositions of its assets described in the loan and security agreement. In the event the Company were to violate any covenants or if White Oak has reason to believe that the Company has violated any covenants, including a significant adverse event clause, and such violations are not cured pursuant to the terms of the loan and security agreement, the Company would be in default under the loan and security agreement, which would entitle lenders to exercise their remedies, including the right to accelerate the debt, upon which the Company may be required to repay all amounts then outstanding under the loan and security agreement. As of December 31, 2015, the Company was in compliance with all covenants except for the covenant relating to obtaining and audit opinion that does not include a going concern explanatory paragraph. As of December 31, 2015, the Company was in compliance with all covenants; however, there was an anticipated default of the covenants listed in Section 6.2(a)(i) and Section 8.2(a), with respect to Section 6.2(a)(i), as of December 31, 2015, which was cured by the Forbearance Agreement as discussed below. The Company is currently in default of this requirement and certain covenants and other events of default listed in Sections 6.1(c), 6.2(a)(i), 6.2(a)(iv), 6.10, 8.2(a) and 8.2(b) of the loan and security agreement with White Oak (the “Specified Events of Default”). On April 19, 2016, the Company entered into a Forbearance Agreement with White Oak (“Forbearance Agreement”) whereby White Oak granted forbearance of the Specified Events of Default until August 17, 2016 in exchange for a $150,000 non-refundable transaction fee. Pursuant to the Forbearance Agreement, on April 21, 2016, the Company made a prepayment to White Oak, with respect to our obligations under the loan and security agreement with White Oak, in the amount of $5.0 million from the Company’s restricted account. Additionally, the outstanding obligations under the White Oak loan will become due on or before August 17, 2016. As of December 31, 2015, the debt was classified as a short-term liability. Future annual payments due on the debt outstanding as of December 31, 2015 are as follows (in thousands): 2016 45,790 Total remaining payments 45,790 Less: Amount representing interest (10,649 ) 35,141 Less: Current portion of long-term debt 35,141 Long-term debt, net of current portion $ —

Restructuring

Restructuring	12 Months Ended
	Dec. 31, 2015
Restructuring and Related Activities [Abstract]
Restructuring	Restructuring In November 2015, the Company initiated a cost-saving restructuring plan in order to align its headcount to reduce operating expenses, consolidate its back-office operations by closing its office in United Kingdom and relocate its headquarter. This restructuring plan would impact approximately 35 full-time positions in its Mountain View, California office and 9 full-time employees in its international offices. The Company recorded restructuring charges of approximately $1.7 million consisting of employee severance and termination benefits, operating lease cancellation fees and expenses related to closing down its United Kingdom office. The Company recorded employee severance costs provided under an ongoing benefit arrangement once they are both probable and estimable in accordance with the provisions of ASC 712. The Company accounted for lease cancellation fees and closing down our United Kingdom office in accordance with ASC 420. Under ASC 420, the Company established a liability for a cost associated with an exit or disposal activity, when the liability was incurred, rather than at the date that the Company committed to an exit plan. The Company reassesses the expected cost to complete the exit or disposal activities at the end of each reporting period and adjusts its remaining estimated liabilities, if necessary. The Company agreed to pay $0.5 million of broker commission to the third party who assisted the Company to negotiate an early termination of its office in Mountain View, California. The Company recorded $0.2 million as exit costs related to the closing off its office in United Kingdom. The Company has classified approximately $1.5 million of these charges as restructuring expense and $188,000 as a component of cost of sales. The Company has completed phase one of its restructuring activities in the fourth quarter of 2015 and expects to complete phase 2 by the end of 2016. The Company's restructuring activities for the year ended December 31, 2014 and 2013 were not material. The table below presents the restructuring activities for the year ended December 31, 2015 (in thousands): Employee Severance and Termination Benefits Operating Lease Cancellation Exit Cost Total Accrued restructuring balance as of January 1, 2015 $ — $ — $ — $ — Additional accruals 1,027 500 200 1,727 Cash payments (146 ) — — (146 ) Accrued restructuring balance as of December 31, 2015 $ 881 $ 500 $ 200 $ 1,581

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2015
Equity [Abstract]
Stockholders' Equity	Stockholders' Equity 2013 Private Placement Transaction In March 2013, the Company executed an “at the market” agreement pursuant to which the Company may have offered to sell shares of common stock up to an aggregate offering price of up to $25.0 million . In July 2013, the Company exercised its right to terminate the agreement. No shares were offered or sold pursuant to the agreement. On July 30, 2013, the Company entered into a securities purchase agreement to sell an aggregate of 2,845,528 shares of its common stock at a per share price of $12.30 and warrants to purchase an aggregate of 3,414,634 shares of common stock at a per warrant price of $1.25 in a private placement transaction. The warrants were comprised of the following three series: Series A warrants exercisable for an aggregate 1,138,211 shares of common stock, with an exercise price equal to $12.30 ; Series B warrants exercisable for an aggregate 1,138,211 shares of common stock, with an exercise price equal to $15.00 per share; and Series C warrants exercisable for an aggregate 1,138,211 shares of common stock, with an exercise price equal to $20.00 per share. Series A warrants were subject to mandatory exercise subsequent to the receipt of regulatory approval for the new 6Fr Magellan catheter in the U.S., which occurred in February 2014. The financing resulted in gross proceeds to the Company of approximately $39.3 million prior to placement fees and offering costs of approximately $2.1 million . At the closing of the private placement financing, the Company entered into an investor rights agreement with the purchasers of the shares and warrants in which the Company agreed to file a registration statement covering resale of the shares and the purchasers agreed not to transact in any shares of the Company’s common stock for a one -year period following the closing, subject to certain exceptions. In the first quarter of 2014, subsequent to the receipt of regulatory approval for the new Magellan 6Fr Robotic Catheter in the U.S., Series A warrants for 1.1 million shares of the Company’s common stock were exercised for total proceeds of $14.0 million in accordance with the terms and conditions of a securities purchase agreement dated July 30, 2013. All of the Series A Warrants were mandatorily exercised in the first quarter of 2014 pursuant to the Company’s achievement of a regulatory milestone as set forth in the Series A Warrants. 2014 Warrant Exchange On July 30, 2014, the Company entered into a definitive agreement (the “Exchange Agreement”) with certain warrantholders to cancel and exchange (the “Exchange”) an aggregate of 1,022,117 of the Company’s outstanding Series B Warrants and an aggregate of 1,022,117 of the Company’s outstanding Series C Warrants. In exchange, the Company issued warrants (the “Exchange Warrants”) to purchase an aggregate of 2,672,837 shares of common stock. The Exchange was completed in August 2014. The Exchange Warrants are comprised of the following two tranches: (a) Series B/C Exchange Warrants (“Series B/C Exchange Warrants”) exercisable for an aggregate of 2,044,235 shares of common stock, with an exercise price equal to $11.30 per share, the NASDAQ consolidated closing bid price for the Common Stock on July 29, 2014, the last completed trading day before the Exchange Agreement was executed (the “Closing Bid Price”); and (b) Series D Warrants (“Series D Warrants”) exercisable for an aggregate of 628,602 shares of common stock, with an exercise price equal to the Closing Bid Price. The Series B/C Exchange Warrants were subject to mandatory exercise within 14 days of issuance and were exercised in August 2014, resulting in gross proceeds to the Company of approximately $23.1 million . The Series D Warrants have an exercise period of five years, and if fully exercised, would result in additional gross proceeds to the Company of approximately $7.1 million . The Series B Warrants and Series C Warrants previously carried an expiration date of August 2015 . The remaining Series B Warrants and Series C Warrants not included in the Exchange will remain outstanding until their exercise or expiration. As a result of a change in the terms and conditions of the Series B and C Warrants, the transaction was treated as a modification of the original award using the accounting guidance in ASC 718-20-35-3, this guidance implies that the entity repurchases the original instrument by issuing a new instrument of equal or greater value, incurring additional incremental value. Incremental cost shall be measured as the excess, if any, of the fair value of the modified award over the fair value of the original award immediately before its terms are modified, measured based on the share price, Black-Scholes options pricing model and other pertinent factors at that date. These variables include the Company’s expected stock price volatility over the term of the award, expected term, risk-free interest rate and expected dividend rate. The Company recorded $2.9 million warrant exchange charge in the consolidated statement of operations during the year ended December 31, 2014 based upon the difference between the fair value of the Series B and C Warrants immediately prior to the exchange and the fair value of the newly issued Series B/C Exchange Warrants and Series D Warrants. 2015 Private Placement of Redeemable Convertible Preferred Stock and Warrants On March 11, 2015, the Company entered into a securities purchase agreement (“Purchase Agreement”) to sell an aggregate of 53,846 shares of Series A convertible preferred stock at a per share price of $650 . After receipt of Requisite Stockholder Approval on May 12, 2015, the Series A convertible preferred stock converted into 5,509,492 shares of common stock. The conversion ratio was equal to the number obtained by dividing (i) the sum of $650 and the amount of any accrued but unpaid dividends by (ii) $0.65 . The amount of accrued but unpaid dividends included as part of the conversion calculation included an initial rate of 2% (the “first period dividend”) plus an increase of 2% in the second quarter of 2015 (the “second period dividend”) based on the number of days the Series A convertible preferred stock remained outstanding. As a result of the Requisite Stockholder Approval, the first period dividend and second period dividend were the only dividends included in the conversion calculation. On the date of the issuance, the allocated fair value of the common stock was greater than the proceeds received for the Series A convertible preferred stock. As such, the Company accounted for the beneficial conversion features under ASC 470-20, Debt with Conversion and Other Options . The Company recorded a deemed dividend charge of $35.5 million for the accretion of a discount on the Series A convertible preferred stock resulting from an allocation of a portion of the proceeds to the warrants and a beneficial conversion feature embedded within the Series A convertible preferred stock, which equals the amount by which the estimated fair value of the common stock issuable upon conversion of the issued Series A convertible preferred stock exceeded the proceeds from such issuance, and a cumulative Series A convertible preferred stock dividend of $0.8 million . Additionally, upon conversion of the preferred stock, a deemed dividend of $15.3 million was recorded due to the discount on the preferred stock created by allocating a portion of the proceeds to the warrants. The deemed dividend and cumulative dividend were non-cash transactions and reflected below net loss to arrive at net loss allocable to common stockholders. As part of the Purchase Agreement, the Company also issued Series E Warrants to the participating investors to purchase an aggregate of 5,384,600 shares of common stock with an exercise period of two years from the date of issuance. On the issuance date, the exercise price for the Series E Warrants was the lesser of $9.75 per share or a 50% premium on the per share trailing volume-weighted average share price of the common stock on NASDAQ for the ten trading days ending on dates specified in the form of Series E Warrants filed with the SEC. However, certain of the Series E Warrants could not be exercised until the Requisite Stockholder Approval was obtained. As a result of this contingency which was deemed outside the Company’s control as well as the variable number of underlying shares due to the floating exercise price, such Series E Warrants did not meet the criteria for classification as equity under ASC 815. As such, the Company classified the Series E Warrants as current liabilities at fair value upon issuance. The Series E Warrants were subject to re-measurement at each balance sheet date, with any change in fair value recognized as warrant expense, a component of other income (expense) reflected within the statement of operations. The Company used a third party valuation that utilized the Monte Carlo simulation model to estimate the fair value of the Series A convertible preferred stock and Series E Warrants. The valuation used a simulation of the Company’s periodic stock price, expected volatility of the price, adjusted for conversion price, and the remaining contractual term of the Series E Warrants. The fair value of the Series E Warrants was $14.8 million upon issuance. Once the Requisite Stockholder Approval was obtained on May 12, 2015, there was sufficient authorized shares underlying the warrants and the exercise price was fixed at $9.75 per share such that the variable number of shares that could be issued became fixed. As a result, all criteria for classification of the Series E Warrants as equity were met. The Company reclassified the warrant liability amounting to $17.8 million to additional paid-in capital, which equals to the fair value of the Company’s warrant liability on May 12, 2015. The change in fair value of $3.0 million was recorded on the consolidated statements of operations for the year ended December 31, 2015. The Company had incurred and capitalized approximately $0.5 million of costs associated with this offering, which were recorded as an offset to additional paid-in capital on the consolidated balance sheets. Accumulated Other Comprehensive Income (Loss) The component of accumulated other comprehensive income (loss), net of tax for years ended December 31, 2015 and 2014 are as follows (in thousands): Unrealized Gains (Losses) on Securities Foreign Currency Translation Losses Total December 31, 2015: Beginning balance $ 392 $ (87 ) $ 305 Net current-period other comprehensive loss (464 ) (51 ) (515 ) Ending Balance $ (72 ) $ (138 ) $ (210 ) December 31, 2014 : Beginning balance $ 373 $ (13 ) $ 360 Net current-period other comprehensive loss 19 (74 ) (55 ) Ending Balance $ 392 $ (87 ) $ 305

Stock-based Compensation

Stock-based Compensation	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based Compensation	Stock-Based Compensation On September 22, 2015, the Company effected a reverse stock split of its common stock by a ratio of 1-for-10 (the “Reverse Split”). As a result of the Reverse Split every ten outstanding shares of common stock became one share of common stock. No fractional shares were issued in connection with the Reverse Split. A stockholder who would otherwise have been entitled to receive a fractional share of common stock received a cash payment equal to the closing sales price of the Company’s common stock on September 22, 2015 as reported on the NASDAQ times the amount of the fractional share. The Reverse Split also changed the number of shares of common stock that the Company is authorized to issue from 300,000,000 to 30,000,000 but did not change the par value of the Company’s common or preferred stock or the number of authorized shares of preferred stock. The Reverse Split resulted in a proportionate adjustment to the per share exercise price and the number of shares of common stock issuable upon the exercise of outstanding warrants and stock options, as well as the number of shares of common stock issuable upon the vesting of restricted stock units. All of the information in these financial statements has been presented to reflect the impact of the 1-for-10 Reverse Split on a retroactive basis. Stock Option and Equity Incentive Plans 2002 Stock Option Plan The Company’s 2002 Stock Option Plan (the “2002 Plan”) was created for the purpose of issuing stock options to employees, directors and consultants of the Company. Options granted under the 2002 Plan were either incentive stock options (“ISO”) or nonqualified stock options (“NSO”). ISOs may be granted only to Company employees (including officers and directors), whereas NSOs may be granted to Company employees and consultants. Options expire on terms as determined by the board of directors but not more than ten years after the date of grant. The Company reserved a total of 457,901 shares of its common stock for issuance under its 2002 Plan. Upon effectiveness of the Company’s IPO in November 2006, the Company ceased issuing stock options under the 2002 Plan. At that time, all shares remaining available for grant under the 2002 Plan became available for grant instead under the 2006 Equity Incentive Plan. However, cancelled shares under the 2002 Plan do not become available for grant under the 2006 Equity Incentive Plan. All outstanding options granted under the 2002 Plan continue to be administered under the 2002 Plan. Stock options granted under the 2002 Plan provided employee option holders the right to elect to exercise unvested options in exchange for restricted common stock. Unvested shares were subject to a repurchase right held by the Company at the original issuance price in the event the optionees’ employment is terminated either voluntarily or involuntarily. For exercises of employee options, this right usually lapsed 25% on the first anniversary of the vesting start date and in 36 equal monthly amounts thereafter. These repurchase terms were considered to be a forfeiture provision and did not result in variable accounting. As of December 31, 2015, there were no unvested shares outstanding. 2006 Equity Incentive Plan In August 2006, the Company’s board of directors approved the 2006 Equity Incentive Plan (the “2006 Plan”) to be effective on the date of the Company’s IPO. The 2006 Plan provides for the grant of ISOs, non-statutory stock options, restricted stock awards, restricted stock unit awards, stock appreciation rights, performance-based stock awards, and other forms of equity compensation, or collectively, stock awards, and performance-based cash awards, all of which may be granted to employees, including officers, non-employee directors and consultants. Options expire on terms as determined by the board of directors but not more than ten years after the date of grant. The Company initially reserved a total of 200,000 shares for issuance under the 2006 Plan in addition to those shares which remained available for grant under the 2002 Plan. In addition, the number of shares of common stock reserved for issuance under the 2006 Plan automatically increases on January 1 st each year by the lowest of (a) 4% of the total number of shares of our common stock outstanding on December 31st of the preceding calendar year, (b) 350,000 shares, or (c) a number determined by the board of directors that is less than (a) or (b). At December 31, 2015, 336,642 shares were available for grant under the 2006 Plan. Option activity under both the 2002 Plan and the 2006 Plan for 2015 is as follows: Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term Aggregate Intrinsic Value (in thousands) (in years) (in thousands) Balance at January 1, 2015 919 $ 16.88 7.8 $ — Granted 91 $ 9.18 Exercised (1 ) $ 5.23 2 Cancelled (219 ) $ 24.06 23 Balance at December 31, 2015 790 $ 14.08 7.4 $ — Options vested and expected to vest at December 31, 2015 673 $ 14.56 6.0 $ — Options vested at December 31, 2015 361 $ 19.49 7.2 $ — The weighted-average grant-date fair value of options granted in 2015, 2014, and 2013 was $5.11 , $6.22 and $12.49 per share, respectively. The total fair value of options that vested in 2015, 2014 and 2013 was $1.6 million , $1.9 million and $2.6 million , respectively. The estimated grant date fair values of the employee stock options were calculated using the following assumptions: Years Ended December 31, 2015 2014 2013 Expected volatility 73% 73% 77% - 89% Risk-free interest rate 1.3% 1.4% 0.6% - 1.5% Expected term (in years) 4.13 4.31 4.38 - 4.57 Dividend yield —% —% —% As of December 31, 2015, total unamortized stock-based compensation related to unvested stock options was $1.6 million , with a weighted-average remaining recognition period of 2.17 years. The intrinsic value of exercised stock options is calculated based on the difference between the exercise price and the quoted closing market price of the Company’s common stock on the exercise date. The total intrinsic value of stock options exercised in 2014, 2013 and 2012 was $2,000 , $0.6 million , and $19,000 , respectively. The options outstanding, vested and currently exercisable by exercise price under both the 2002 Plan and the 2006 Plan at December 31, 2015 are as follows (share options in thousands): Options Outstanding Options Exercisable and Vested Exercise Price Number of Options Weighted- Average Remaining Contractual Life Number of Options Weighted- Average Exercise Price Weighted- Average Remaining Contractual Life (in years) (in years) $6.45-$6.48 145 8.94 — $ — 0 $6.49-$9.18 214 9.03 65 $ 7.69 9.09 $9.19-$20.75 206 7.45 107 $ 14.79 6.60 $20.76-$77.60 225 4.83 189 $ 26.24 4.62 790 7.41 361 $ 19.49 6.02 Restricted stock unit activity under the 2006 Plan is as follows: Restricted Stock Units Weighted- Average Grant- Date Fair Value (in thousands) Balance at January 1, 2015 84 $ 18.02 Awarded 568 $ 8.93 Vested (29 ) $ 14.18 Cancelled (138 ) $ 11.14 Balance at December 31, 2015 485 $ 9.57 The fair value of restricted stock units is the quoted market price of the Company’s common stock as of the close of the grant date. The total fair value of shares vested pursuant to restricted stock units in 2015, 2014, and 2013 was $2.6 million , $2.5 million and $2.6 million , respectively. As of December 31, 2015, total unamortized stock-based compensation related to unvested restricted stock units was $1.0 million , with a weighted-average remaining recognition period of 2.67 years. 2006 Employee Stock Purchase Plan In August 2006, the Company’s board of directors approved the 2006 Employee Stock Purchase Plan (the “Stock Purchase Plan”) which became effective upon the Company’s IPO. Commencing on January 1, 2007, the Stock Purchase Plan allows participating employees to contribute up to 15% of their earnings, up to a maximum of $25,000 , to purchase shares of the Company’s stock at a price per share equal to the lower of (a) 85% of the fair market value of a share of our common stock on the first date of the offering period, or (b) 85% of the fair market value of a share of our common stock on the date of purchase. The Company’s board of directors may specify offerings with durations of not more than 27 months, and may specify shorter purchase periods within each offering. Each offering will have one or more purchase dates on which shares of the Company’s common stock will be purchased for employees participating in the offering. The Company initially reserved a total of 62,500 shares of common stock for issuance under the Stock Purchase Plan. In addition, the plan provides for automatic increases on January 1st, from January 1, 2007 through January 1, 2016, by the lesser of (a) 2% of the total number of shares of common stock outstanding on December 31st of the preceding calendar year, (b) 75,000 shares of common stock or (c) a number determined by the board of directors that is less than (a) and (b). The estimated fair values of the shares issued under the Stock Purchase Plan were calculated using the following assumptions: Years Ended December 31, 2015 2014 2013 Expected volatility 78% 111% 65% Risk-free interest rate 0.1% 0.1% 0.1% Expected term (in years) 0.50 0.50 0.50 Dividend yield —% —% —% Total Stock-based Compensation Total stock-based compensation expense was allocated to cost of revenues, research and development and selling, general and administrative expense as follows (in thousands): Years Ended December 31, 2015 2014 2013 Cost of revenues $ 233 $ 230 $ 402 Research and development 632 704 1,320 Selling, general and administrative 1,893 1,898 3,167 Total $ 2,758 $ 2,832 $ 4,889 Stock-based compensation expense related to stock options granted to non-employees is recognized on an accelerated basis as the stock options are earned. The final measurement occurs at the later of a performance commitment or when performance is complete. The Company believes that the fair value of the stock options is more reliably measurable than the fair value of the services received. The fair value of the stock options granted is calculated at each reporting date using the Black-Scholes option valuation model. Stock-based compensation expense charged to operations for options granted to non-employees for the years ended December 31, 2015 and 2014, 2013 was immaterial. In fiscal 2015, the Company granted 318,721 PSUs to executives and employees in-lieu of cash bonuses with vesting based on the Company’s 2015 corporate goals and department goals over the vesting period of 1 year. Each PSU represents the right to receive one share of the Company’s common stock upon the vesting of such PSU, and is subject to the terms of the Company’s 2006 Equity Incentive Plan. Any PSUs not vesting on a vesting date due to the Company’s corporate goals and department goals for the fiscal year 2015 not meeting the target for such fiscal year established by the Compensation Committee shall be forfeited. The grant date fair value of these awards was $2.9 million . The Company recognized stock-based compensation expense of $0.8 million related to the PSUs as a result of achieving department goals. In fiscal 2014, the Company awarded 41,407 restricted stock units to certain executives, which are subject to certain financial performance targets for the year ending December 31, 2015 and their continued employment, before vesting can occur. The Compensation Committee will determine the achievement for these restricted stock units within 30 days after the Company files its annual report on Form 10-K for the year ended December 31, 2015. Of these awards, 22,388 awards were cancelled as a result of employee terminations. No compensation cost related to these awards was recorded in 2015 and 2014 based on the estimated probability of achieving the financial performance targets for the year ending December 31, 2015.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company’s pre-tax loss consists of the following (in thousands): Years Ended December 31, 2015 2014 2013 Domestic $ (46,382 ) $ (54,457 ) $ (55,877 ) Foreign 222 239 270 Pre-tax loss $ (46,160 ) $ (54,218 ) $ (55,607 ) The Company had significant losses in 2015 and as such the $47,000 tax expense for fiscal year 2015 relates to foreign taxes. The Company’s effective tax rate differs from the U.S. federal statutory rate as follows: Years Ended December 31, 2015 2014 2013 Federal tax benefit at statutory rate (34 )% (34 )% (34 )% Permanent difference due to non-deductible expenses 3 % 2 % 1 % State tax benefit, net of federal impact — % — % — % Change in deferred tax asset valuation allowance 31 % 33 % 33 % General business credits — % (1 )% — % Effective tax rate — % — — % — — % The tax effects of temporary differences and carryforwards that give rise to significant portions of the deferred tax assets are as follows (in thousands): December 31, 2015 2014 Net operating loss carryforwards $ 46,942 $ 108,245 Research and development credits 4,193 10,564 Capitalized research and development 19,803 19,926 Fixed assets 2,243 2,464 Stock-based compensation 1,442 3,214 Accruals, reserves and other 2,637 2,259 Intangibles 694 857 77,954 147,529 Less: Valuation allowance (77,954 ) (147,529 ) Net deferred tax asset $ — $ — At December 31, 2015 , the Company has federal and state net operating loss carryforwards of approximately $117.1 million and $125.3 million , respectively, available to offset future taxable income. These net operating loss carryforwards will expire in varying amounts from 2016 through 2035 if not utilized. The net operating loss carryforwards include $1.9 million which relates to stock option deductions that will be recognized through additional paid-in capital when utilized. As such, these deductions are not reflected in our deferred tax assets. The Company also has federal and California research and development tax credit carryforwards of $0.2 million and $8.2 million , respectively, available to offset future taxes payable. The federal credits begin to expire in 2035 , while the state credits have no expiration. Due to uncertainty surrounding realization of the deferred tax assets in future periods, the Company has placed a 100% valuation allowance against its net deferred tax assets. The valuation allowance increased (decreased) by $(69.6) million , $17.1 million and $21.4 million during the years ended December 31, 2015 , 2014 and 2013 , respectively. At such time as it is determined that it is more likely than not that the deferred tax assets are realizable, the valuation allowance will be reduced. Sections 382 and 383 of the Internal Revenue Code of 1986, as amended, provide for annual limitations on the utilization of net operating loss and research and experimentation credit carryforwards if the Company were to undergo an ownership change, as defined in Section 382. In general, an ownership change occurs whenever the percentage of the shares of a corporation owned, directly or indirectly, by 5 -percent shareholders, as defined in Section 382, increases by more than 50% percentage points over the lowest percentage of the shares of such corporation owned, directly or indirectly, by such 5 -percent shareholders at any time over the preceding three years. Based on an analysis under Section 382 of the Internal Revenue Code, we experienced various ownership changes through 2015 which substantially limit the future use of our pre-change NOLs and certain other pre-change tax attributes per year. We have excluded the NOLs and R&D credits that will expire as a result of the annual limitations in the deferred tax assets as of December 31, 2015. To the extent that we do not utilize our carry-forwards within the applicable statutory carry-forward periods, either because of Section 382 limitations or the lack of sufficient taxable income, the carry-forwards will expire unused. The Company has not provided for U.S. federal income and foreign withholding taxes on any undistributed earnings from non-U.S. operations because such earnings are intended to be reinvested indefinitely outside of the United States. If these earnings were distributed, foreign tax credits may become available under current law to reduce or eliminate the resulting U.S. income tax liability. As of December 31, 2015 , there is $0.8 million in cumulative foreign earnings upon which U.S. income taxes have not been provided. The Company files income tax returns in the United States, various state jurisdictions and in the countries of United Kingdom and Germany. As of December 31, 2015 , the Company’s federal tax returns for years ended 2012 through the current period and most state returns for the years ended 2011 through the current period are still open to examination. In addition, all of the net operating loss and research and development credit carryforwards that may be used in future years are still subject to adjustment. The Company is also subject to examination in the United Kingdom and Germany beginning in 2010 through the current period. There are no tax examinations currently in progress. A reconciliation of the beginning and ending balance of unrecognized tax benefits is as follows (in thousands): Years Ended December 31, 2015 2014 2013 Balance at beginning of period $ 4,220 $ 3,864 $ 3,358 Additions based on tax positions related to the current year 165 384 301 Additions (Reduction) based on tax positions related to prior years (2,287 ) (28 ) 205 Balance at end of period $ 2,098 $ 4,220 $ 3,864 As of December 31, 2015 , the company had a total of $2.1 million unrecognized tax benefits, none of which would affect the effective tax rate upon realization. While it is often difficult to predict the final outcome of any particular uncertain tax position, management does not believe that it is reasonably possible that the estimates of unrecognized tax benefits will change significantly in the next twelve months. We recognize interest and penalties related to uncertain tax positions in income tax expense. As of December 31, 2015 , we have no accrued interest or penalties related to uncertain tax positions. The Company does not anticipate that total unrecognized tax benefits will significantly change due to the settlement of audits and the expiration of statute of limitations period to December 31, 2015.

Net Loss per Share

Net Loss per Share	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Net Loss per Share	Net Loss per Share The following table sets forth the computation of basic and diluted net loss per share (in thousands, except per share data): Year Ended December 31, 2015 2014 2013 Net loss $ (46,207 ) $ (54,246 ) $ (55,722 ) Deemed dividend related to beneficial conversion feature of Series A convertible preferred stock and accretion of discount (35,546 ) — — Cumulative dividend on Series A convertible preferred stock (812 ) — — Net loss attributable to common stockholders $ (82,565 ) $ (54,246 ) $ (55,722 ) Weighted average shares used to compute basic and diluted net loss per share 16,871 11,723 7,905 Basic and diluted net loss per share $ (4.89 ) $ (4.63 ) $ (7.05 ) The following securities that could potentially dilute basic net loss per share are not included in the calculation of diluted net loss per share because to do so would be anti-dilutive as of the end of each period presented (in thousands): December 31, 2015 2014 2013 Stock options outstanding 790 919 778 Unvested restricted stock units 485 84 132 Estimated shares to be issued under the employee stock purchase plan 3 13 4 Warrants 6,079 927 3,481

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Segment Information	Segment Information The Company operates its business in one operating segment: the development and marketing of medical devices. The Company’s chief operating decision maker is its Chief Executive Officer who reviews the financial information presented on a consolidated basis for the purpose of making operating decisions and assessing financial performance. The Company’s medical robotics systems are developed and marketed to a broad base of hospitals and distributors in the United States and internationally. The Company considers all such sales to be part of a single operating segment. Information regarding total revenue is as follows (in thousands): Years ended December 31, 2015 2014 2013 Revenues: United States $ 7,124 $ 10,041 $ 8,580 International (1) 8,944 9,454 8,402 Total revenues $ 16,068 $ 19,495 $ 16,982 The majority of the Company’s long-lived assets are located in the United States. Revenues are attributed to countries based on the location of the customer. (1) For fiscal year 2015, Italy and Belgium accounted for 11% and 10% of total revenues, respectively. For fiscal year 2014, only Japan within international accounted for 13% of total revenues. No single location within international accounted for greater than 10% of total revenues in fiscal year 2013.

Quarterly Data (unaudited)

Quarterly Data (unaudited)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Quarterly Data (unaudited)	Quarterly Data (unaudited) The following table represents certain unaudited quarterly information for the eight quarters ended December 31, 2015. This data has been derived from unaudited consolidated financial statements that, in the opinion of the Company’s management, include all adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of such information when read in conjunction with the Company’s annual audited consolidated financial statements and notes thereto appearing elsewhere in this report. These operating results are not necessarily indicative of results for any future period (in thousands, except per share data): First Quarter Second Quarter As Restated (2)(3) Third Quarter (5) Fourth Quarter (4) 2015: Revenues $ 5,794 $ 3,092 $ 3,183 $ 3,999 Gross profit 1,156 358 204 (715 ) Net loss (11,933 ) (12,507 ) (10,227 ) (11,540 ) Net loss attributable to common stockholders (11,933 ) (48,865 ) (10,227 ) (11,540 ) Basic and diluted net loss per common share (1) (0.90 ) (3.00 ) (0.54 ) (0.61 ) 2014: Revenues $ 3,699 $ 6,887 $ 3,877 $ 5,032 Gross profit 398 1,902 702 2 Net loss attributable to common stockholders (14,445 ) (12,290 ) (15,594 ) (11,917 ) Basic and diluted net loss per common share (1) (1.40 ) (1.10 ) (1.30 ) (0.90 ) (1) The Company’s financial statements have been retroactively adjusted to reflect the reverse stock split of its outstanding shares of common stock at a ratio of one-for-ten effective on September 22, 2015. (2) Net loss, net loss attributable to common stockholders and basic and diluted net loss per common share for the second quarter of 2015 includes the impact of $2.9 million of change in fair value for warrant liability. (3) Net loss attributable to common stockholders and basic and diluted net loss per common share for the second quarter of 2015 includes the impact of non-cash charges of $35.5 million and $0.8 million for the deemed dividend related to beneficial conversion feature of Series A convertible preferred stock and accretion of discount, and cumulative dividend on Series A convertible preferred stock, respectively. The net loss attributable to common stockholders and basic and diluted net loss per common share during the second quarter of 2015 have been restated to reflect a $15.3 million adjustment for the portion of the deemed dividend relating to the accretion of discount. (4) Net loss, Net loss attributable to common stockholders and basic and diluted net loss per common share for the fourth quarter of 2015 include the impact of $1.7 million in restructuring expense. (5) Net income and basic and diluted net loss per common share for the third quarter of 2014 include the impact of the warrant exchange of $2.9 million .

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2015
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events As disclosed in the Company’s Current Report on Form 8-K filed with the SEC on April 20, 2016, the Company, Auris Surgical Robotics, Inc. ("Parent"), and Pineco Acquisition Corp., a wholly owned subsidiary of Parent ("Merger Sub"), entered into an Agreement and Plan of Merger (the "Merger Agreement"), pursuant to which, subject to satisfaction or waiver of the conditions therein, Merger Sub will merge with and into the Company (the "Merger"), with the Company surviving the Merger as a wholly owned subsidiary of Parent. Subject to the terms of the Merger Agreement, which has been unanimously approved by the board of directors of the Company, at the effective time of the Merger (the "Effective Time"), each share of Company common stock issued and outstanding immediately prior to the Effective Time (other than shares owned by Parent or any of its subsidiaries, shares held by the Company as treasury stock, and shares held by stockholders who have perfected their statutory rights of appraisal under Section 262 of the Delaware General Corporation Law) will be converted into the right to receive $4.00 in cash, without interest (the "Merger Consideration"). Immediately prior to the Effective Time, each outstanding option to purchase shares of Company common stock granted under a Company stock plan will be cancelled for no consideration. Additionally, immediately prior to the Effective Time, each outstanding award of restricted stock units with respect to shares of Company common stock (each, an "RSU Award") granted pursuant to a Company stock plan will be fully vested and cancelled and, in exchange therefor, each holder of any such cancelled RSU Award will be entitled to receive, in consideration of the cancellation of such RSU Award and in settlement therefor, a payment in cash of an amount equal to the product of (i) the Merger Consideration multiplied by (ii) the number of restricted stock units subject to such RSU Award, without interest (less any required tax withholdings). To the extent an RSU Award is subject to performance conditions, the number of restricted stock units that vest will be determined (A) for RSU Awards with a performance period that by its terms has ended prior to the Effective Time, based on actual performance through the end of such performance period, and (B) for RSU Awards with a performance period that by its terms has not ended prior to the Effective Time, by deeming such performance conditions to have been satisfied at 100% of the target levels specified in the applicable equity plans and award agreements. The Merger Agreement contains customary representations, warranties and covenants of the Company, Parent and Merger Sub, including, among others, covenants by the Company to conduct its business in the ordinary course during the interim period between execution of the Merger Agreement and consummation of the Merger and not to engage in certain kinds of transactions during such period. The Company has also agreed, subject to certain exceptions, not to enter into discussions concerning, or provide confidential information in connection with, any alternative transaction. Parent has agreed, promptly following the Effective Time, to pay or cause to be paid in full all of the Company’s obligations under the loan and security agreement with White Oak. In addition, each of the parties has agreed to use its reasonable best efforts to cause the Merger to be consummated. The board of directors of the Company has agreed to hold a stockholder meeting to consider and vote upon the adoption of the Merger Agreement. The Merger is subject to satisfaction of the conditions set forth in the Merger Agreement, including the approval by the stockholders of the Company; that none of the lender parties to the loan and security agreement with White Oak shall have exercised any of the rights and remedies available to any of them under either the loan and security agreement with White Oak or the Forbearance Agreement upon the occurrence and during the continuance of an Event of Default (as defined in the loan and security agreement with White Oak) or as a result of the Company breaching or being in default of any of the covenants, agreements or other provisions of the Forbearance Agreement, other than delivering notice of such Event of Default under the loan and security agreement with White Oak or such breach or default under the Forbearance Agreement; that none of the Rollover Stockholders (as defined below) shall have invalidated or terminated the stock purchase agreement with Parent (as described below); and other customary closing conditions. The obligation of each party to consummate the Merger is also conditioned upon the other party’s representations and warranties being true and correct (subject to certain materiality exceptions), and the other party having performed in all material respects its obligations under the Merger Agreement, and the obligation of Parent to consummate the Merger is conditioned upon the Company not having suffered a material adverse effect. The Merger Agreement contains certain termination rights for both the Company and Parent, and provides that, upon termination of the Merger Agreement under specified circumstances, the Company may be required to pay Parent a termination fee of $3.325 million , including if the Company were to terminate the Merger Agreement in order to accept an unsolicited superior acquisition proposal. Concurrently with the Company, Parent and Merger Sub entering into the Merger Agreement, holders of approximately 65.4% of the outstanding shares of Company common stock, including all of the directors and executive officers of the Company, Larry Feinberg and certain affiliated entities, Jack Schuler and certain affiliated entities, and an affiliated entity of Lawrence T. Kennedy, Jr., entered into voting agreements in favor of Parent and the Company (collectively, the "Voting Agreements") pursuant to which they agreed, among other things, to vote their shares of Company common stock in favor of the adoption of the Merger Agreement, against any alternative acquisition proposal, and against any reorganization, recapitalization, dissolution, liquidation or winding-up of the Company or any other extraordinary transaction involving the Company other than the Merger. The Voting Agreements terminate upon the termination of the Merger Agreement in accordance with its terms, including if the Company were to terminate the Merger Agreement in order to accept an unsolicited superior acquisition proposal. Additionally, concurrently with entering into the Merger Agreement, certain Company stockholders owning approximately 64.6% of the outstanding shares of the Company common stock, including Larry Feinberg and certain affiliated entities, Jack Schuler and certain affiliated entities and an affiliated entity of Lawrence T. Kennedy, Jr. (the "Rollover Stockholders"), executed and delivered a stock purchase agreement with Parent whereby each Rollover Stockholder has unconditionally agreed to acquire shares of preferred stock of Parent immediately following the Effective Time on the terms set forth therein, in exchange for an investment of approximately $49 million (representing the aggregate amount of consideration payable to the Rollover Stockholders in the Merger). Further, concurrently with the Company entering into the Merger Agreement, the Company and the lender parties under the loan and security agreement with White Oak entered into the Forbearance Agreement. The "going concern" qualification in the opinion and report for this report constitutes an Event of Default (as defined in the loan and security agreement with White Oak). Pursuant to the Forbearance Agreement, the lender parties have agreed not to pursue any remedies related to such "going concern" default during the period from the date of the Forbearance Agreement through the earlier of (x) August 17, 2016 and (y) the date when the forbearance period under the Forbearance Agreement is otherwise terminated (such period, the "Forbearance Period"). In addition, the Company expects that it will fail to comply with the minimum liquidity required by Section 6.10(a) of the loan and security agreement with White Oak at some point during the Forbearance Period. The Company’s failure to comply with such minimum liquidity requirement would constitute an Event of Default under the loan and security agreement with White Oak. Under the Forbearance Agreement, the Lender Parties have agreed not to pursue any remedies related to such minimum liquidity default during the Forbearance Period. The Forbearance Agreement provides that the Company shall, as promptly as reasonably practicable and in any event at or before the expiration of the Forbearance Period, (x) consummate the Merger and (y) pay and satisfy all obligations owed by the Company to the Lender Parties in full in cash. The failure to consummate the Merger during the Forbearance Period would constitute a default under the Forbearance Agreement. Pursuant to the Forbearance Agreement, the Company has prepaid $5.0 million of the outstanding principal amount of the term loan under the loan and security agreement with White Oak. For additional details regarding the terms and conditions of the Merger Agreement, refer to the Merger Agreement and other documentation filed as exhibits to the Current Report on Form 8-K filed with the SEC on April 20, 2016. Additional information regarding the proposed transaction, including risks associated with the proposed transaction, will be contained in a definitive proxy statement to be filed by the Company with the SEC. No assurance can be given that the Merger will be completed.

Summary of Significant Accoun25

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Company has prepared the accompanying consolidated financial statements in accordance with generally accepted accounting principles in the United States of America (“GAAP”). The Company’s fiscal year ends on December 31. The consolidated financial statements include the accounts of the Company and its subsidiaries. All significant intercompany accounts and transactions have been eliminated.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Significant estimates relate to the recognition of revenue, the evaluation of customer credit risk, the valuation of investments, inventory valuations, warrant valuations, the determination of impairment of assets, stock-based compensation, loss contingencies and the valuation of our deferred tax assets, among others. Actual results could differ from those estimates.
Revenue Recognition	Revenue Recognition The Company’s revenues are primarily derived from the sale of the Sensei System and the Magellan System and the associated catheters as well as the sale of customer service contracts, which includes post-contract customer support (“PCS”). The Company sells its products directly to customers as well as through distributors. Under the Company’s revenue recognition policy, revenues are recognized when persuasive evidence of an arrangement exists, title and risk of loss has passed, delivery to the customer has occurred or the services have been fully rendered, the sales price is fixed or determinable and collectability is reasonably assured. • Persuasive Evidence of an Arrangement . Persuasive evidence of an arrangement for sales of systems is generally determined by a sales contract signed and dated by both the customer and the Company, including approved terms and conditions or the receipt of an approved purchase order. Evidence of an arrangement for the sale of disposable products is determined through an approved purchase order from the customer. Evidence of an arrangement for the sale of customer service is determined through either a signed sales contract or an approved purchase order from the customer. Sales are generally not subject to any performance, cancellation, termination or return rights. • Delivery . • Systems and Disposable Products. Typically, ownership of systems, catheters and other disposable products passes to customers upon shipment, at which time delivery is deemed to be complete. • Customer Service Revenue. The Company recognizes customer service revenue from the sale of its PCS contracts which includes planned and corrective maintenance services, software updates, bug fixes, and warranty. Revenue from customer services, whether sold individually or as a separate unit of accounting in a multi-element arrangement, is deferred and amortized over the service period, which is typically one year. • Multiple-element Arrangements. It is common for the sale of Sensei and Magellan Systems to include multiple elements which have standalone value and qualify as separate units of accounting. These elements commonly include the sale of the system and a product maintenance plan, in addition to installation of the system and initial training. Less commonly, these elements may include the sale of certain disposable products or other elements. For multiple-element arrangements revenue is allocated to each element based on their relative selling prices. Relative selling prices are based first on vendor specified objective evidence (“VSOE”), then on third-party evidence of selling price (“TPE”) when VSOE does not exist, and then on management’s best estimate of the selling price (“ESP”) when VSOE and TPE do not exist. Because the Company has neither VSOE nor TPE for its system, the allocation of revenue is based on ESP for the systems sold. The objective of ESP is to determine the price at which the Company would transact a sale, had the product been sold on a stand-alone basis. The Company determines ESP for its systems by considering multiple factors, including, but not limited to, features and functionality of the system, geographies, type of customer, and market conditions. The Company regularly reviews ESP and maintains internal controls over the establishment and updates of these estimates. • Sales Price Fixed or Determinable. The Company assesses whether the sales price is fixed or determinable at the time of the transaction. Sales prices are documented in the executed sales contract or purchase order received prior to shipment The Company’s standard terms do not allow for contingencies, such as trial or evaluation periods, refundable orders, or extended payment terms payments contingent upon the customer obtaining financing or other contingencies which would impact the customer’s obligation. In situations where these or other contingencies are included, all related revenue is deferred until the contingency is resolved. In the third quarter of 2012, the Company began shipping systems under a limited commercial evaluation program to allow certain strategic accounts to install and utilize systems for a limited trial period of three to six months while the purchase opportunity is being evaluated by the hospital. Systems under this program remain the property of the Company and are recorded in inventory and a sale only occurs upon the issuance of a purchase order from the customer. • Collectability. The Company assesses whether collection is probable based on a number of factors, including the customer’s past transaction history and credit worthiness. If collection of the sales price is not deemed probable, the revenue is deferred and recognized at the time collection becomes probable, which is usually upon receipt of cash. The Company’s sales contracts generally do not allow the customer the right of cancellation, refund or return, except as provided under the Company’s standard warranty. If such rights were allowed, all related revenues would be deferred until such rights expired. Significant management judgments and estimates are made in connection with the determination of revenue to be recognized and the period in which it is recognized. If different judgments and estimates were utilized, the amount of revenue to be recognized and the period in which it is recognized could differ materially from the amounts reported.
Concentration of Credit Risk and Other Risks and Uncertainties	Concentration of Credit Risk and Other Risks and Uncertainties Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents, short-term investments and accounts receivable. Cash and cash equivalents are deposited in demand and money market accounts at one financial institution. At times, such deposits may be in excess of insured limits. The Company has not experienced any losses on its deposits of cash and cash equivalents. The Company had four customers who constituted 19% , 18% , 12% and 12% , respectively of the Company’s net accounts receivable at December 31, 2015. The Company had four customers who constituted 26% , 14% , 12% , and 12% , respectively of the Company’s net accounts receivable at December 31, 2014. The Company carefully monitors the creditworthiness of potential customers. As of December 31, 2015, the Company has not experienced any significant losses on its accounts receivable. Two customers accounted for 11% and 11% , respectively of total revenues for fiscal year 2015. Two customers accounted for 13% and 10% , respectively of total revenues for fiscal year 2014. One customer accounted for 10% of total revenues for fiscal year 2013. Most of the products developed by the Company require clearance from the U.S. Food and Drug Administration (“FDA”) or corresponding approval by foreign regulatory agencies prior to commercial sales. These clearances and approvals are required for both the Sensei and Magellan Systems and all related catheters and accessories: Sensei: The Company received CE Mark approval to market its Sensei System in Europe in the fourth quarter of 2006 and received CE Mark approval to market its Artisan ® Control Catheter in Europe in May 2007. The Company received FDA clearance for the marketing of its Sensei System and Artisan Extend catheters for manipulation, positioning and control of certain mapping catheters during electrophysiology (“EP”) procedures in the United States in May 2007. Magellan: At the current time the Company has received clearance and approval for the Magellan System and the Magellan 6Fr, 9Fr and 10Fr Robotic Catheters and related accessories in various territories. The Company received CE Mark approval for its Magellan System in July 2011 and received CE Mark approval for the Magellan 9Fr Robotic Catheter and related accessories in October 2011. The Magellan 6Fr Robotic Catheter received CE Mark approval in October 2014, while the Magellan 10Fr Robotic Catheter received CE Mark approval in April 2015. The Company received FDA clearance for marketing its Magellan System, including the Magellan 9Fr Robotic Catheter and accessories in June 2012, the Magellan 6Fr Robotic Catheter in February 2014, and the Magellan 10Fr Robotic Catheter in July 2015. The FDA clearances and CE Mark approvals enable the company to initiate use of all Magellan Systems and catheters with its customers in the United States, the European Union and certain other geographies. However, there can be no assurance that current products or any new products the Company develops in the future will receive the clearances or approvals necessary to allow the Company to market those products in certain desirable markets. If the Company is denied clearance or approvals or clearance or approvals are delayed, it could have a material adverse impact on the Company. The medical device industry is characterized by frequent and extensive litigation and administrative proceedings over patent and other intellectual property rights. Whether a product infringes a patent involves complex legal and factual issues, the determination of which is often difficult to predict, and the outcome may be uncertain until the court has entered final judgment and all appeals are exhausted. The Company’s competitors may assert, and have asserted in the past, that the Company’s products or the use of the Company’s products are covered by United States or foreign patents held by them. This risk is heightened due to the numerous issued and pending patents relating to the use of catheter-based procedures in the medical technology field.
Loss Contingencies	Loss Contingencies The Company evaluates potential loss contingencies as circumstances dictate. Should a specific loss contingency meet the definition of a liability under authoritative accounting guidance, the Company would record a loss and a liability. As of December 31, 2015, the Company had not recorded any loss contingencies as liabilities. However, if estimates and assumptions change in the future, the Company may record charges to its financial statements. This could materially impact its operating results and financial position.
Foreign Currency	Foreign Currency Assets and liabilities of non-U.S. subsidiaries that operate in a local currency environment, where that local currency is the functional currency, are translated at current exchange rates as of the end of the accounting period. The related revenues and expenses are translated at average exchange rates in effect during the period. Net exchange gains and losses resulting from translation are excluded from income and are recorded as part of accumulated other comprehensive income. Transactions denominated in a foreign currency are revalued at the current exchange rate at the transaction date and any related gains and losses are reflected in investment and other income, net in the consolidated statements of income.
Fair Value Measurements	Fair Value Measurements GAAP defines fair value as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, authoritative guidance establishes a three-tier value hierarchy, which prioritizes the inputs used in measuring fair value as follows: • Level 1 Inputs Quoted prices (unadjusted) in active markets for identical assets or liabilities. • Level 2 Inputs Inputs other than quoted prices in active markets that are observable either directly or indirectly. • Level 3 Inputs Unobservable inputs in which there is little or no market data, which require the Company to develop its own assumptions. This hierarchy requires the use of observable market data when available and to minimize the use of unobservable inputs when determining fair value.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Carrying amounts of certain of the Company’s financial instruments, including cash and cash equivalents, accounts receivable, and accounts payable approximate fair value due to their short maturities.
Cash and Cash Equivalents, and Restricted Cash	Cash and Cash Equivalents, and Restricted Cash The Company considers all highly liquid investments with maturities of three months or less at the time of purchase to be cash equivalents. Cash and cash equivalents, and restricted cash include money market funds and various deposit accounts, which are readily convertible to cash and are stated at cost, which approximates market. Pursuant to the Company’s loan and security agreement executed in 2013, the Company is obligated to maintain $5.0 million of restricted cash subject to lenders’ control.
Short-Term Investments	Short-Term Investments Available-for-sale investments. The Company determines the appropriate classification of investments at the time of purchase and evaluates such classification as of each balance sheet date. The Company classifies all investments with maturities greater than three months at the time of purchase as short-term investments as they are subject to use within one year in current operations. The Company makes investments based upon specific guidelines approved by its board of directors with a view to liquidity and capital preservation and regularly reviews its investments for performance. As of December 31, 2015, all of the Company’s investments have been classified as available-for-sale and are carried on the balance sheet at fair value with the unrealized gains and losses, if any, included in other comprehensive income within stockholders’ equity. Any unrealized losses which are determined to be other than temporary are included in earnings. Other-than-temporary impairment. The Company periodically evaluates its investments for impairment. In the event that the carrying value of an investment exceeds its fair value and the decline in fair value is determined to be other than temporary, an impairment charge is recorded and a new cost basis for the investment is established. The primarily differentiating factors the Company considered to determine whether a decline in value is other than temporary are our intent and ability to retain its investment in the issuer for a period of time sufficient to allow for any anticipated recovery in market value, the length of the time and the extent to which the market value of the investment has been less than cost, the financial condition and near-term prospects of the issuer. Given the current market conditions, these judgments could prove to be wrong, and companies with relatively high credit ratings and solid financial conditions may not be able to fulfill their obligations. During the year ended December 31, 2013, the Company recorded pre-tax losses of $0.6 million related to a decline in the value of our investment in Luna Innovations Incorporated common stock that the Company concluded were other-than-temporary. No impairment loss were recorded during the years ended December 31, 2015 and 2014. As of December 31, 2015 and 2014, net unrealized gains (loss) on investments of $(0.4) million and $0.02 million , net of tax, respectively, were included in accumulated other comprehensive income (loss). Significant management judgment is required in determining whether an other-than-temporary decline in the fair value of an investment exists. Changes in the Company’s assessment of the valuation of investments could materially impact future operating results and financial position.
Accounts Receivable and Allowance for Doubtful Accounts	Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable primarily include amount due from hospitals and distributors. The Company establishes allowances for doubtful accounts based on a review of the credit profiles of customers, contractual terms and conditions, current economic trends and historical collection experience. The allowance for doubtful accounts is reassessed each period based on management’s assessment of historical expected net collections and other collection indicators.
Inventories	Inventories Inventories, which includes material, labor and overhead costs, are stated at standard cost, which approximates actual cost, determined on a first-in, first-out basis, and not in excess of net realizable value. The cost basis of the Company’s inventory is reduced for any products that are considered excessive or obsolete based upon assumptions about future demand and market conditions. In the event actual demand for our inventory differs from our best estimates or we fail to receive necessary regulatory approvals, further reduction in our basis of inventory may become necessary.
Property and Equipment, Net	Property and Equipment, Net Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation of property and equipment is computed using the straight-line method over their estimated useful lives of two to five years. Leasehold improvements are amortized on a straight-line basis over the lesser of their useful life or the term of the lease. Depreciation expense was $1.0 million , $2.6 million and $2.9 million for the years ended December 31, 2015, 2014 and 2013, respectively.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company evaluates the recoverability of its long-lived assets in accordance with authoritative accounting guidance. When events or changes in circumstances indicate that the carrying value of long-lived assets may not be recoverable, the Company recognizes such impairment if the net book value of such assets exceeds the future undiscounted cash flows attributable to such assets. Should an impairment exist, the impairment loss would be measured based on the excess carrying value of the asset over the asset’s fair value or discounted estimates of future cash flows attributable to the assets. As of December 31, 2015, the Company had $2.3 million of property and equipment, net. If estimates or the related assumptions change in the future, the Company may record impairment charges to reduce the carrying value of certain groups of these assets. Changes in the valuation of long-lived assets could materially impact the Company’s operating results and financial position.
Advertising Expense	Advertising Expense The Company expenses advertising costs as incurred. Advertising costs are recorded in general, sales and marketing expenses within the accompanying consolidated statements of operations was $0.6 million and $0.7 million for fiscal year 2015 and 2014, respectively and was immaterial for fiscal year 2013
Stock-Based Compensation	Stock-Based Compensation The Company accounts for share-based compensation plan in accordance with the provisions of the Financial Accounting Standards Board (“FASB”) Accounting Standard Codification ("ASC") No. 718-10-30, Stock Compensation Initial Measurement, which requires the measurement and recognition of compensation expense for all stock-based awards made to employees and directors including employee stock options, restricted stock units (“RSUs”), performance stock units (“PSUs”) and employee stock purchases under our Employee Stock Purchase Plan (“ESPP”) based on estimated fair values and recognizes stock-based compensation expense, net of estimated forfeitures, on a ratable basis over the requisite service period. The Company estimates the fair value of stock options granted using the Black-Scholes-Merton (“BSM”) option valuation model. The BSM option valuation model is used to determine the fair value of stock-based awards with the following assumptions • Expected Volatility . The Company’s estimate of volatility is based on the historical volatilities of its stock price. • Expected Term . The Company estimates the expected term based on its historical settlement experience related to vesting and contractual terms while giving consideration to awards that have life cycles less than the contractual terms and vesting schedules in accordance with authoritative guidance. • Risk-Free Interest Rate. The risk-free interest rate that the Company uses in the BSM option valuation model is the implied yield in effect at the time of option grant based on U.S. Treasury zero-coupon issues with a remaining term equivalent to the expected term of its option grants. For ESPP grants, the Company uses the 6-month Constant Maturity Treasury rate. • Dividend Yield. The Company has never paid any cash dividends on its common stock and it does not anticipate paying any cash dividends in the foreseeable future. Consequently, the Company uses a dividend yield of zero in the BSM option valuation model. The Company measures the fair value of RSUs and PSUs using the closing stock price of a share of the Company’s common stock on the grant date. In addition, the Company also estimates a forfeiture rate for its stock options and RSUs. The Company estimates its forfeiture rate based on an analysis of its actual forfeitures based on actual forfeiture experience, analysis of employee turnover behavior and other factors. The impact from any forfeiture rate adjustment would be recognized in full in the period of adjustment and, if the actual number of future forfeitures differs from its estimates, the Company might be required to record adjustments to its stock-based compensation in future periods. For PSUs, the Company recognizes stock-based compensation expense based on the probable outcome that the performance condition will be achieved.
Research and Development	Research and Development Research and development costs are charged to expense as incurred. Research and development costs include, but are not limited to, payroll and other personnel expenses, prototype materials, laboratory supplies, and consulting costs.
Income Taxes	Income Taxes The Company accounts for income taxes using the liability method whereby deferred tax asset and liability account balances are determined based on differences between financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. Valuation allowances are established to reduce deferred tax assets when management estimates, based on available objective evidence, that it is more likely than not that the benefit will not be realized for the deferred tax assets. The Company accounts for uncertainty in income taxes using a two-step approach to recognizing and measuring uncertain tax positions. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained on audit, including resolution of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount that is more than 50% likely of being realized upon settlement. The Company recognizes interest and penalties related to unrecognized tax benefits as a component of income tax expense. As of December 31, 2015, the Company has no accrued interest or penalties related to uncertain tax positions. The Company does not anticipate that total unrecognized tax benefits will significantly change due to the settlement of audits and the expiration of statute of limitations periods in 2015.
Comprehensive Loss	Comprehensive Loss The Company follows the accounting standards for the reporting and presentation of comprehensive income (loss) and its components. Comprehensive loss includes all changes in stockholders’ equity during a period from non-owner sources. Comprehensive loss for each of the years ended December 31, 2015, 2014 and 2013 was equal to net loss adjusted for unrealized gains and losses on investments, reclassifications of realized gains and losses on investments to other income (expense) and foreign currency translation adjustments.
Computation of Net Loss Per Share	Computation of Net Loss Per Share Basic net loss per 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 share is computed using the weighted-average number of shares and diluted potential shares outstanding during the period. Dilutive potential shares are excluded when the effect would be to reduce a net loss per share. The Company’s dilutive potential shares primarily consists of outstanding common stock options, warrants, estimated shares to be issued under the Company’s employee stock purchase plan and unvested restricted stock, which have not been included in the computation of diluted net loss per share for all periods as the result would be anti-dilutive.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes the revenue recognition requirements in ASC 605, Revenue Recognition . ASU 2014-09 is based on the principle that revenue is recognized to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. This new guidance is effective for annual reporting periods beginning after December 15, 2016, including interim periods within those fiscal years. Early adoption is not permitted. The Company is currently assessing the impact of the adoption of ASU 2014-09 on its consolidated financial statements. In August 2014, the FASB issued ASU No. 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 205-40 ): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. The ASU provides guidance on determining when and how to disclose going-concern uncertainties in the financial statements. The new standard requires management to perform interim and annual assessments of an entity’s ability to continue as a going concern within one year of the date the financial statements are issued. An entity must provide certain disclosures if “conditions or events raise substantial doubt about the entity’s ability to continue as a going concern.” The ASU applies to all entities and is effective for annual periods ending after December 15, 2016, and interim periods thereafter, with early adoption permitted. The Company has been assessing the going concern issue since 2010 on an interim and annual basis and will continue to assess whether the financial conditions based on this new guidance have an impact on the Company’s consolidated financial statements or footnotes. In January 2015, the FASB issued ASU 2015-01, Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items. This ASU eliminates from GAAP the concept of extraordinary items, and is effective for annual periods beginning after December 15, 2015, with early adoption permitted. The change primarily involves presentation and disclosure and, therefore, is not expected to have a material impact on the Company’s financial condition, results of operations or cash flows. In April 2015, the FASB issued ASU 2015-03, Interest-Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Cost , which changes the presentation of debt issuance costs in financial statements. Under the ASU, an entity presents costs in the balance sheet as a direct deduction from the related debt liability rather than as an asset. Amortization of the costs is reported as interest expense. Under current guidance, an entity reports debt issuance costs in the balance sheet as deferred charges (i.e. as an asset). For public companies, the ASU is effective for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years, with early adoption permitted. Entities would apply the new guidance retrospectively to all prior periods. The Company is currently assessing the impact of the adoption of ASU 2015-03 on its consolidated financial statements. In July 2015, the FASB issued ASU 2015-11, Simplifying the Measurement of Inventory . Under this ASU, inventory will be measured at the “lower of cost and net realizable value” and options that currently exist for “market value” will be eliminated. The ASU defines net realizable value as the “estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation.” No other changes were made to the current guidance on inventory measurement. ASU 2015-11 is effective for interim and annual periods beginning after December 15, 2016. Early adoption is permitted and should be applied prospectively. The Company does not expect the adoption of this accounting standard update to impact its consolidated financial statements. In November 2015, the FASB issued ASU 2015-17, Balance Sheet Classification of Deferred Taxes , which simplifies the presentation of deferred income taxes. This ASU amends the existing guidance to require presentation of deferred tax assets and liabilities as noncurrent within a classified statement of financial position. The Company early adopted ASU 2015-17 effective December 2015 on a prospective basis. The adoption did not have an impact on the financial statements of the Company. In February 2016, the FASB issued ASU 2016-02, Leases , which require a lessee to recognize lease assets and liabilities on the balance sheet for all arrangements with terms longer than 12 months. Lessor accounting remains largely consistent with existing U.S. GAAP. The new standard takes effect in 2019 for public business entities and 2020 for all other entities. The Company is currently assessing the impact of the adoption of ASU 2016-02 on its consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting . ASU 2016-09 requires among other things that all excess tax benefits and tax deficiencies (including tax benefits of dividends on share-based payment awards) to be recognized as income tax expense or benefit in the income statement. The tax effects of exercised or vested awards should be treated as discrete items in the reporting period in which they occur. An entity also should recognize excess tax benefits, and assess the need for a valuation allowance, regardless of whether the benefit reduces taxes payable in the current period. The ASU also requires excess tax benefits to be classified along with other income tax cash flows as an operating activity in the statement of cash flows. This new guidance is effective for annual reporting periods beginning after December 15, 2016, including interim periods within those fiscal years. Early adoption is permitted. The Company is currently assessing the impact of the adoption of ASU 2016-09 on its consolidated financial statements.

Fair Value of Assets and Liab26

Fair Value of Assets and Liabilities (Tables)	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Amortized Cost and Fair Value of Assets, with Gross Unrealized Gains and Losses	The amortized cost and fair value of assets, along with gross unrealized gains and losses, were as follows (in thousands): Cash, Cash Equivalents, Short-term Investments and Restricted Cash Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Balance Sheet Classification Cash and cash Equivalents Short-term Investments Restricted Cash December 31, 2015: Cash $ 1,408 $ — $ — $ 1,408 $ 1,408 $ — $ — Money market funds 25,080 — — 25,080 18,967 — 6,113 Corporate equity securities 1,572 — (71 ) 1,501 — 1,501 — $ 28,060 $ — $ (71 ) $ 27,989 $ 20,375 $ 1,501 $ 6,113 December 31, 2014: Cash $ 3,586 $ — $ — $ 3,586 $ 3,586 $ — $ — Money market funds 26,318 — — 26,318 20,942 — 5,376 Corporate equity securities 1,572 401 — 1,973 — 1,973 — $ 31,476 $ 401 $ — $ 31,877 $ 24,528 $ 1,973 $ 5,376
Fair Value Hierarchy of Company's Assets and Liabilities	The fair value hierarchy of the Company’s assets and liabilities that are measured at fair value, by level, is as follows (in thousands): Fair Value Measurements Using Quoted Prices in Active Markets for Identical Assets (Level 1 Inputs) Significant other Observable Inputs (Level 2 Inputs) Unobservable Inputs (Level 3 Inputs) Total December 31, 2015: Assets: Money market funds $ 25,080 $ — $ — $ 25,080 Corporate equity securities 1,501 — — 1,501 $ 26,581 $ — $ — $ 26,581 December 31, 2014: Money market funds $ 26,318 $ — $ — $ 26,318 Corporate equity securities 1,973 — — 1,973 $ 28,291 $ — $ — $ 28,291
Changes in Level 3 Liabilities Measured at Fair value on a Recurring Basis	The changes in Level 3 liabilities measured at fair value on a recurring basis was as follow (in thousands): Level 3 Input for Year Ended December 31, 2015 (In thousands) Balance at December 31, 2014 $ — Additions at March 11, 2015 (14,776 ) Change in fair value of warrant liability (2,993 ) Reclassification to additional paid-in capital 17,769 Balance at December 31, 2015 $ —

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts (in thousands) December 31, 2015 2014 2013 Balance at Beginning of the Year $ — $ 554 $ 554 Additions Charges to Cost and Expenses 49 21 — Write-offs (26 ) (475 ) — Balance Before Recoveries $ 23 $ 100 $ 554 Less: Recoveries — (100 ) — Balance at the End of the Year $ 23 $ — $ 554
Components of inventories, Net	Inventories, net (in thousands) December 31, 2015 2014 Raw materials $ 2,613 $ 4,996 Work in process 3,575 4,571 Finished goods 2,471 1,925 Inventories $ 8,659 $ 11,492
Property and equipment, net	Property and equipment, net (in thousands) December 31, 2015 2014 Furniture and leasehold improvements $ 11,329 $ 11,455 Laboratory equipment 12,158 11,374 Computer equipment and software 2,956 2,911 26,443 25,740 Less: Accumulated depreciation and amortization (24,118 ) (23,412 ) Property and equipment, net $ 2,325 $ 2,328
Accrued liabilities	Accrued liabilities (in thousands) December 31, 2015 2014 Accrued restructuring $ 1,581 $ — Accrued salaries, commission, bonus and benefits 1,094 2,835 Tax accruals 333 274 Accrued royalties 330 594 Accrued legal and other professional fees 228 169 Clinical related accruals 60 394 Other accrued expenses 487 676 Total $ 4,113 $ 4,942

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Rent expense on a straight-line basis	Rent expense on a straight-line basis was as follows (in thousands): Years Ended December 31, 2015 2014 2013 Rent expense $ 2,782 $ 2,613 $ 2,310
Future Minimum Payments under Operating Leases	At December 31, 2015, future minimum payments under the leases are as follows (in thousands): Years ended December 31, Future Minimum Lease Payments 2016 $ 1,728 2017 297 2018 610 2019 628 2020 647 Thereafter 4,443 Total $ 8,353

Short-term and Long-term Debt (

Short-term and Long-term Debt (Tables)	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Future Annual Payments Due on Amounts Outstanding	Future annual payments due on the debt outstanding as of December 31, 2015 are as follows (in thousands): 2016 45,790 Total remaining payments 45,790 Less: Amount representing interest (10,649 ) 35,141 Less: Current portion of long-term debt 35,141 Long-term debt, net of current portion $ —

Restructuring (Tables)

Restructuring (Tables)	12 Months Ended
	Dec. 31, 2015
Restructuring and Related Activities [Abstract]
Restructuring and Related Costs	The table below presents the restructuring activities for the year ended December 31, 2015 (in thousands): Employee Severance and Termination Benefits Operating Lease Cancellation Exit Cost Total Accrued restructuring balance as of January 1, 2015 $ — $ — $ — $ — Additional accruals 1,027 500 200 1,727 Cash payments (146 ) — — (146 ) Accrued restructuring balance as of December 31, 2015 $ 881 $ 500 $ 200 $ 1,581

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2015
Equity [Abstract]
Component of Accumulated Other Comprehensive Income (Loss), Net of Tax	The component of accumulated other comprehensive income (loss), net of tax for years ended December 31, 2015 and 2014 are as follows (in thousands): Unrealized Gains (Losses) on Securities Foreign Currency Translation Losses Total December 31, 2015: Beginning balance $ 392 $ (87 ) $ 305 Net current-period other comprehensive loss (464 ) (51 ) (515 ) Ending Balance $ (72 ) $ (138 ) $ (210 ) December 31, 2014 : Beginning balance $ 373 $ (13 ) $ 360 Net current-period other comprehensive loss 19 (74 ) (55 ) Ending Balance $ 392 $ (87 ) $ 305

Stock-based Compensation (Table

Stock-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Option Activity Under Company's 2002 Stock Option Plan and 2006 Plan for 2014	Option activity under both the 2002 Plan and the 2006 Plan for 2015 is as follows: Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term Aggregate Intrinsic Value (in thousands) (in years) (in thousands) Balance at January 1, 2015 919 $ 16.88 7.8 $ — Granted 91 $ 9.18 Exercised (1 ) $ 5.23 2 Cancelled (219 ) $ 24.06 23 Balance at December 31, 2015 790 $ 14.08 7.4 $ — Options vested and expected to vest at December 31, 2015 673 $ 14.56 6.0 $ — Options vested at December 31, 2015 361 $ 19.49 7.2 $ —
Assumptions Used to Estimate Grant Date Fair Values of Stock Options	The estimated grant date fair values of the employee stock options were calculated using the following assumptions: Years Ended December 31, 2015 2014 2013 Expected volatility 73% 73% 77% - 89% Risk-free interest rate 1.3% 1.4% 0.6% - 1.5% Expected term (in years) 4.13 4.31 4.38 - 4.57 Dividend yield —% —% —%
Options Outstanding, Vested and Currently Exercisable By Exercise Price under Both 2002 Plan And 2006 Plan	The options outstanding, vested and currently exercisable by exercise price under both the 2002 Plan and the 2006 Plan at December 31, 2015 are as follows (share options in thousands): Options Outstanding Options Exercisable and Vested Exercise Price Number of Options Weighted- Average Remaining Contractual Life Number of Options Weighted- Average Exercise Price Weighted- Average Remaining Contractual Life (in years) (in years) $6.45-$6.48 145 8.94 — $ — 0 $6.49-$9.18 214 9.03 65 $ 7.69 9.09 $9.19-$20.75 206 7.45 107 $ 14.79 6.60 $20.76-$77.60 225 4.83 189 $ 26.24 4.62 790 7.41 361 $ 19.49 6.02
Summary of Restricted Stock Unit Activity	Restricted stock unit activity under the 2006 Plan is as follows: Restricted Stock Units Weighted- Average Grant- Date Fair Value (in thousands) Balance at January 1, 2015 84 $ 18.02 Awarded 568 $ 8.93 Vested (29 ) $ 14.18 Cancelled (138 ) $ 11.14 Balance at December 31, 2015 485 $ 9.57
Assumptions Used to Estimate Grant Date Fair Values of Shares Issued Under the ESPP	The estimated fair values of the shares issued under the Stock Purchase Plan were calculated using the following assumptions: Years Ended December 31, 2015 2014 2013 Expected volatility 78% 111% 65% Risk-free interest rate 0.1% 0.1% 0.1% Expected term (in years) 0.50 0.50 0.50 Dividend yield —% —% —%
Total Stock-based Compensation	Total stock-based compensation expense was allocated to cost of revenues, research and development and selling, general and administrative expense as follows (in thousands): Years Ended December 31, 2015 2014 2013 Cost of revenues $ 233 $ 230 $ 402 Research and development 632 704 1,320 Selling, general and administrative 1,893 1,898 3,167 Total $ 2,758 $ 2,832 $ 4,889

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Summary of Company's Pre-tax Loss	The Company’s pre-tax loss consists of the following (in thousands): Years Ended December 31, 2015 2014 2013 Domestic $ (46,382 ) $ (54,457 ) $ (55,877 ) Foreign 222 239 270 Pre-tax loss $ (46,160 ) $ (54,218 ) $ (55,607 )
Summary of Company's Effective Tax Rate Differs from U.S. Federal Statutory Rate	The Company’s effective tax rate differs from the U.S. federal statutory rate as follows: Years Ended December 31, 2015 2014 2013 Federal tax benefit at statutory rate (34 )% (34 )% (34 )% Permanent difference due to non-deductible expenses 3 % 2 % 1 % State tax benefit, net of federal impact — % — % — % Change in deferred tax asset valuation allowance 31 % 33 % 33 % General business credits — % (1 )% — % Effective tax rate — % — — % — — %
Summary of Tax Effects of Temporary Differences and Carryforwards That Give Rise to Significant Portions of Deferred Tax Assets	The tax effects of temporary differences and carryforwards that give rise to significant portions of the deferred tax assets are as follows (in thousands): December 31, 2015 2014 Net operating loss carryforwards $ 46,942 $ 108,245 Research and development credits 4,193 10,564 Capitalized research and development 19,803 19,926 Fixed assets 2,243 2,464 Stock-based compensation 1,442 3,214 Accruals, reserves and other 2,637 2,259 Intangibles 694 857 77,954 147,529 Less: Valuation allowance (77,954 ) (147,529 ) Net deferred tax asset $ — $ —
Reconciliation of Beginning and Ending Balance of Unrecognized Tax Benefits	A reconciliation of the beginning and ending balance of unrecognized tax benefits is as follows (in thousands): Years Ended December 31, 2015 2014 2013 Balance at beginning of period $ 4,220 $ 3,864 $ 3,358 Additions based on tax positions related to the current year 165 384 301 Additions (Reduction) based on tax positions related to prior years (2,287 ) (28 ) 205 Balance at end of period $ 2,098 $ 4,220 $ 3,864

Net Loss per Share (Tables)

Net Loss per Share (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net Income (Loss) Per Share	The following table sets forth the computation of basic and diluted net loss per share (in thousands, except per share data): Year Ended December 31, 2015 2014 2013 Net loss $ (46,207 ) $ (54,246 ) $ (55,722 ) Deemed dividend related to beneficial conversion feature of Series A convertible preferred stock and accretion of discount (35,546 ) — — Cumulative dividend on Series A convertible preferred stock (812 ) — — Net loss attributable to common stockholders $ (82,565 ) $ (54,246 ) $ (55,722 ) Weighted average shares used to compute basic and diluted net loss per share 16,871 11,723 7,905 Basic and diluted net loss per share $ (4.89 ) $ (4.63 ) $ (7.05 )
Common Stock Equivalents that are Not Included In the Calculation of Diluted Net Loss Per Share	The following securities that could potentially dilute basic net loss per share are not included in the calculation of diluted net loss per share because to do so would be anti-dilutive as of the end of each period presented (in thousands): December 31, 2015 2014 2013 Stock options outstanding 790 919 778 Unvested restricted stock units 485 84 132 Estimated shares to be issued under the employee stock purchase plan 3 13 4 Warrants 6,079 927 3,481

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Information Regarding Total Revenue	Information regarding total revenue is as follows (in thousands): Years ended December 31, 2015 2014 2013 Revenues: United States $ 7,124 $ 10,041 $ 8,580 International (1) 8,944 9,454 8,402 Total revenues $ 16,068 $ 19,495 $ 16,982

Quarterly Data (unaudited) (Tab

Quarterly Data (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Summary of certain unaudited quarterly information for the eight quarters	The following table represents certain unaudited quarterly information for the eight quarters ended December 31, 2015. This data has been derived from unaudited consolidated financial statements that, in the opinion of the Company’s management, include all adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of such information when read in conjunction with the Company’s annual audited consolidated financial statements and notes thereto appearing elsewhere in this report. These operating results are not necessarily indicative of results for any future period (in thousands, except per share data): First Quarter Second Quarter As Restated (2)(3) Third Quarter (5) Fourth Quarter (4) 2015: Revenues $ 5,794 $ 3,092 $ 3,183 $ 3,999 Gross profit 1,156 358 204 (715 ) Net loss (11,933 ) (12,507 ) (10,227 ) (11,540 ) Net loss attributable to common stockholders (11,933 ) (48,865 ) (10,227 ) (11,540 ) Basic and diluted net loss per common share (1) (0.90 ) (3.00 ) (0.54 ) (0.61 ) 2014: Revenues $ 3,699 $ 6,887 $ 3,877 $ 5,032 Gross profit 398 1,902 702 2 Net loss attributable to common stockholders (14,445 ) (12,290 ) (15,594 ) (11,917 ) Basic and diluted net loss per common share (1) (1.40 ) (1.10 ) (1.30 ) (0.90 ) (1) The Company’s financial statements have been retroactively adjusted to reflect the reverse stock split of its outstanding shares of common stock at a ratio of one-for-ten effective on September 22, 2015. (2) Net loss, net loss attributable to common stockholders and basic and diluted net loss per common share for the second quarter of 2015 includes the impact of $2.9 million of change in fair value for warrant liability. (3) Net loss attributable to common stockholders and basic and diluted net loss per common share for the second quarter of 2015 includes the impact of non-cash charges of $35.5 million and $0.8 million for the deemed dividend related to beneficial conversion feature of Series A convertible preferred stock and accretion of discount, and cumulative dividend on Series A convertible preferred stock, respectively. The net loss attributable to common stockholders and basic and diluted net loss per common share during the second quarter of 2015 have been restated to reflect a $15.3 million adjustment for the portion of the deemed dividend relating to the accretion of discount. (4) Net loss, Net loss attributable to common stockholders and basic and diluted net loss per common share for the fourth quarter of 2015 include the impact of $1.7 million in restructuring expense. (5) Net income and basic and diluted net loss per common share for the third quarter of 2014 include the impact of the warrant exchange of $2.9 million .

The Company - Additional Inform

The Company - Additional Information (Detail) - USD ($)	Apr. 20, 2016	Apr. 19, 2016	Dec. 31, 2015	Dec. 31, 2014	Aug. 23, 2013
Description of Business [Line Items]
Accumulated net profit or loss from inception			$ (453,929,000)	$ (406,910,000)
Negative working capital			6,900,000
Cash, cash equivalents, short-term investments and restricted cash			28,000,000
White Oak Loan Agreement
Description of Business [Line Items]
Minimum liquidity requirement amount			15,000,000
White Oak Loan Agreement | Subsequent Event
Description of Business [Line Items]
Debt default, non-refundable transaction fee		$ 150,000
Repayments of secured debt	$ 5,000,000	$ 5,000,000
White Oak Loan Agreement | Cash, Cash Equivalents and Investments
Description of Business [Line Items]
Minimum liquidity requirement amount			13,000,000
White Oak Loan Agreement | Accounts Receivable
Description of Business [Line Items]
Minimum liquidity requirement amount			$ 2,000,000
Minimum liquidity requirement, percent of eligible accounts receivable			65.00%		65.00%
Luna Innovations Incorporated | Restricted Cash and Cash Equivalents
Description of Business [Line Items]
Minimum liquidity requirement amount			$ 5,000,000

Summary of Significant Accoun38

Summary of Significant Accounting Policies - Additional Information (Detail)	Sep. 22, 2015shares	May. 12, 2015	Jan. 31, 2010USD ($)	Dec. 31, 2015USD ($)EntityCustomershares	Dec. 31, 2014USD ($)Customershares	Dec. 31, 2013USD ($)Customer	Sep. 21, 2015shares	Aug. 23, 2013USD ($)
Summary Of Significant Accounting Policies [Line Items]
Proposed reverse stock split conversion ratio 1		0.25
Proposed reverse stock split conversion ratio 2		0.1667
Proposed reverse stock split conversion ratio 3		0.125
Stock split conversion ratio	0.1	0.10
Common stock, shares authorized | shares	30,000,000			30,000,000	30,000,000		300,000,000
Deferred and amortized service period				1 year
Number of financial institutions in which cash deposited | Entity				1
Depreciation expense				$ 1,000,000	$ 2,600,000	$ 2,900,000
Property and equipment, net				2,325,000	2,328,000
Advertising costs				600,000	700,000
Luna Innovations Incorporated
Summary Of Significant Accounting Policies [Line Items]
Pre-tax losses related to a decline in the value of our investment						$ 600,000
Available-for-sale securities, other than temporary impairment recorded loss in other expense			$ 600,000	0	0
Net unrealized gains on investments				$ (400,000)	$ 20,000
Minimum
Summary Of Significant Accounting Policies [Line Items]
Limited trial period for commercial evaluation program				3 months
Estimated useful lives				2 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Limited trial period for commercial evaluation program				6 months
Estimated useful lives				5 years
Customer concentration risk | Accounts Receivable
Summary Of Significant Accounting Policies [Line Items]
Number of major customers | Customer				4	4
Customer concentration risk | Accounts Receivable | Customer 1
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage				19.00%	26.00%
Customer concentration risk | Accounts Receivable | Customer 2
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage				18.00%	14.00%
Customer concentration risk | Accounts Receivable | Customer 3
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage				12.00%	12.00%
Customer concentration risk | Accounts Receivable | Customer 4
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage					12.00%
Customer concentration risk | Accounts Receivable | Customer 5
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage				12.00%
Customer concentration risk | Sales
Summary Of Significant Accounting Policies [Line Items]
Number of major customers | Customer				2	2	1
Customer concentration risk | Sales | Customer 1
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage				11.00%	13.00%	10.00%
Customer concentration risk | Sales | Customer 2
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage				11.00%	10.00%
Customer concentration risk | Sales | Single Customer
Summary Of Significant Accounting Policies [Line Items]
Number of major customers | Customer				1		1
White Oak Loan Agreement
Summary Of Significant Accounting Policies [Line Items]
Minimum liquidity requirement amount								$ 15,000,000
Restricted Cash and Cash Equivalents | Letter of Credit [Member]
Summary Of Significant Accounting Policies [Line Items]
Minimum liquidity requirement amount				$ 750,000
Restricted Cash and Cash Equivalents | White Oak Loan Agreement
Summary Of Significant Accounting Policies [Line Items]
Minimum liquidity requirement amount				$ 5,000,000

Fair Value of Assets and Liab39

Fair Value of Assets and Liabilities - Amortized Cost and Fair Value of Assets, with Gross Unrealized Gains and Losses (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash Cash Equivalents And Short Term Investments [Line Items]
Amortized Cost	$ 28,060	$ 31,476
Gross Unrealized Gains	0	401
Gross Unrealized Losses	(71)	0
Fair Value	27,989	31,877
Cash and cash equivalents	20,375	24,528	$ 27,995	$ 32,749
Short-term investments	1,501	1,973
Restricted cash	6,113	5,376
Cash
Cash Cash Equivalents And Short Term Investments [Line Items]
Amortized Cost	1,408	3,586
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	1,408	3,586
Cash and cash equivalents	1,408	3,586
Short-term investments	0	0
Restricted cash	0	0
Money Market Funds
Cash Cash Equivalents And Short Term Investments [Line Items]
Amortized Cost	25,080	26,318
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	25,080	26,318
Cash and cash equivalents	18,967	20,942
Short-term investments	0	0
Restricted cash	6,113	5,376
Corporate Equity Securities
Cash Cash Equivalents And Short Term Investments [Line Items]
Amortized Cost	1,572	1,572
Gross Unrealized Gains	0	401
Gross Unrealized Losses	(71)	0
Fair Value	1,501	1,973
Cash and cash equivalents	0	0
Short-term investments	1,501	1,973
Restricted cash	$ 0	$ 0

Fair Value Hierarchy of Company

Fair Value Hierarchy of Company's Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 26,581	$ 28,291
Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	25,080	26,318
Corporate Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	1,501	1,973
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	26,581	28,291
Level 1 | Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	25,080	26,318
Level 1 | Corporate Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	1,501	1,973
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 2 | Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 2 | Corporate Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 3 | Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 3 | Corporate Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 0	$ 0

Fair Value of Assets and Liab41

Fair Value of Assets and Liabilities - Additional Information (Detail)	May. 12, 2015USD ($)$ / shares	Mar. 11, 2015USD ($)day$ / sharesshares	Jan. 31, 2010USD ($)	Jun. 30, 2015USD ($)	Dec. 31, 2015USD ($)Securities$ / shares	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Jul. 30, 2013shares
Fair Value, Measurement Inputs, Disclosure [Line Items]
Securities in loss position for longer than 12 months | Securities					0
Long term debt, fair value					$ 35,100,000
Common Stock issuable upon exercise of warrants | shares		5,384,600						3,414,634
Warrants exercise period		2 years
Warrants exercise price (in USD per share) | $ / shares	$ 9.75	$ 9.75			$ 9.75
Premium on per share trailing weighted average share price		50.00%
Number trading days | day		10
Fair value of warrants upon issuance	$ 14,800,000	$ 14,800,000
Warrant expense				$ 2,900,000	$ 2,993,000	$ 2,914,000	$ 0
Warrant liability, reclassification to additional paid-in capital	$ 17,800,000				17,800,000
Other income (expense)
Fair Value, Measurement Inputs, Disclosure [Line Items]
Warrant expense					3,000,000
Luna Innovations Incorporated
Fair Value, Measurement Inputs, Disclosure [Line Items]
Available-for-sale securities, other than temporary impairment recorded loss in other expense			$ 600,000		$ 0	$ 0

Fair Value of Assets and Liab42

Fair Value of Assets and Liabilities Changes in Level 3 Liabilities Measured at Fair value on a Recurring Basis (Detail) - USD ($) $ in Thousands	May. 12, 2015	Dec. 31, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Reclassification to additional paid-in capital	$ 17,800	$ 17,800
Balance at December 31, 2015		0
Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at December 31, 2014		0
Additions at March 11, 2015		(14,776)
Change in fair value of warrant liability		(2,993)
Reclassification to additional paid-in capital		$ 17,769

Balance Sheet Components - Allo

Balance Sheet Components - Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Doubtful Accounts
Balance at Beginning of the Year	$ 0	$ 554	$ 554
Additions Charges to Cost and Expenses	49	21	0
Write-offs	(26)	(475)	0
Balance Before Recoveries	23	100	554
Less: Recoveries	0	(100)	0
Balance at the End of the Year	$ 23	$ 0	$ 554

Balance Sheet Components - Comp

Balance Sheet Components - Components of Inventories, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Raw materials	$ 2,613	$ 4,996
Work in process	3,575	4,571
Finished goods	2,471	1,925
Inventories	$ 8,659	$ 11,492

Balance Sheet Components - Prop

Balance Sheet Components - Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 26,443	$ 25,740
Less: Accumulated depreciation and amortization	(24,118)	(23,412)
Property and equipment, net	2,325	2,328
Furniture and leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	11,329	11,455
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	12,158	11,374
Computer equipment and software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 2,956	$ 2,911

Balance Sheet Components - Co46

Balance Sheet Components - Components of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued restructuring	$ 1,581	$ 0
Accrued salaries, commission, bonus and benefits	1,094	2,835
Tax accruals	333	274
Accrued royalties	330	594
Accrued legal and other professional fees	228	169
Clinical related accruals	60	394
Other accrued expenses	487	676
Total	$ 4,113	$ 4,942

Agreements with Intuitive Sur47

Agreements with Intuitive Surgical - Additional Information (Detail) - USD ($) $ in Millions	Jul. 30, 2013	Oct. 31, 2012	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Licenses Agreements [Line Items]
Proceeds from licensing fees		$ 20				$ 20
Stock purchase agreement to sell shares	2,845,528	529,101
Common stock agreement purchase price		$ 10
Agreement amendment period						3 years
Stock purchase agreement recorded in common stock and additional paid-in capital						$ 10
Intuitive Surgical Inc
Licenses Agreements [Line Items]
Cost related to royalty obligations			$ 0.2	$ 0.3	$ 0.2
Intuitive Surgical Inc | Minimum
Licenses Agreements [Line Items]
Royalty obligations per year			$ 0.2

Agreements with Philips - Addit

Agreements with Philips - Additional Information (Detail) - USD ($)	1 Months Ended		12 Months Ended
	Aug. 31, 2015	Feb. 28, 2011	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Technology commercialization cash payments to be received in future		$ 78,000,000
Potential future payment from sublicensing technology under agreement			66.70%
Potential future payment based on royalty obligation under agreement			33.30%
FOSSL-related royalty obligations		between 2014 and 2020
Koninklijke Philips Electronics Nv
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Royalty payment obligation			2017-10
Cost related to royalty obligations			$ 700,000	$ 1,200,000	$ 900,000
Koninklijke Philips Electronics Nv | Minimum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Royalty obligations			$ 0
Amendment to Fiber Optic Shape Sensing and Localization (FOSSL) and Joint Development Agreement (JDA) [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Royalty Payment Description		through October 2017
Increase (Decrease) in Royalty Obligations, Percentage	(50.00%)
Increase (Decrease) in Royalty Obligations Based on Sales, Percentage	(50.00%)
Amendment to Fiber Optic Shape Sensing and Localization (FOSSL) and Joint Development Agreement (JDA) [Member] | Koninklijke Philips Electronics Nv
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Increase (Decrease) in Royalty Obligations Based on Sales, Percentage	(50.00%)

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	Dec. 15, 2015ft²	Dec. 19, 2013$ / sharesshares	May. 09, 2013USD ($)	Dec. 22, 2009plaintifflawsuit	Sep. 30, 2014USD ($)	Mar. 31, 2013USD ($)	Dec. 31, 2015USD ($)ft²	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Other Commitments [Line Items]
Post-contract customer service on sale of Company's systems							1 year
Loss contingency settlement agreement consideration			$ 8,500,000
Loss contingency settlement value funded by insurer and other sources			4,000,000
Settlement paid in stock			4,250,000
Number of trading days		10 days
Settlement paid in cash			$ 250,000
Loss on settlement of litigation					$ (2,900,000)	$ (4,500,000)	$ 0	$ 0	$ (4,500,000)
Issuance of common shares in connection with the litigation settlement | shares		229,854
Common stock issued related to legal settlement per share | $ / shares		$ 18.49
Curry v. Hansen Medical, Inc. et al, Livingstone v. Hansen Medical, Inc. et al, and Prenter v. Hansen Medical, Inc., et al | Pending Litigation
Other Commitments [Line Items]
Number of lead plaintiffs | plaintiff				2
Number of claims | lawsuit				3
Mitsubishi
Other Commitments [Line Items]
Reduction royalty obligation							$ 55,000
Royalty obligation expiration Year							2,018
Cost related to royalty obligations							$ 100,000	$ 100,000	$ 100,000
Mitsubishi | Minimum
Other Commitments [Line Items]
Royalty obligations per year							$ 100,000
California
Other Commitments [Line Items]
Operating lease area leased for office space | ft²	32,552
London, England
Other Commitments [Line Items]
Operating lease expiration year							Jun. 30, 2020
Operating lease area leased for office space | ft²							3,300
Operating lease expiration year							2,015
Exit cost							$ 100,000

Commitments and Contingencies50

Commitments and Contingencies - Rent Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]
Rent expense	$ 2,782	$ 2,613	$ 2,310

Commitments and Contingencies51

Commitments and Contingencies - Future Minimum Payments under Operating Leases (Detail) $ in Thousands	Dec. 31, 2015USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,016	$ 1,728
2,017	297
2,018	610
2,019	628
2,020	647
Thereafter	4,443
Total	$ 8,353

Short-term and Long-term Debt -

Short-term and Long-term Debt - Oxford (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Aug. 31, 2013	Dec. 31, 2011	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jul. 30, 2013
Debt Instrument [Line Items]
Exercise price of common stock warrants (in USD per share)						$ 1.25
Loss on extinguishment of debt			$ 0	$ 0	$ 1,935
Oxford
Debt Instrument [Line Items]
Loan and security agreement		$ 30,000
Interest rate on pay off obligation		9.45%
Interest payment on the original principal		3.95%
Common stock warrants issued		66,079
Exercise price of common stock warrants (in USD per share)		$ 22.70
Expiration date of warrants		December 2,018
Payment of final interest balloon	$ 1,200
Loss on extinguishment of debt	1,900
Unamortized discount from warrants and issuance costs	500
Oxford | Prepayment Penalty
Debt Instrument [Line Items]
Loss on extinguishment of debt before write-off of unamortized costs	900
Oxford | Accrued Balloon Payment
Debt Instrument [Line Items]
Loss on extinguishment of debt before write-off of unamortized costs	$ 500

Short-term and Long-term Debt53

Short-term and Long-term Debt - White Oak (Details)	Apr. 20, 2016USD ($)	Apr. 19, 2016USD ($)	Aug. 23, 2013USD ($)subsidiary	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
White Oak Loan Agreement
Debt Instrument [Line Items]
Number of subsidiaries | subsidiary			2
Minimum liquidity requirement amount			$ 15,000,000
White Oak Loan Agreement | Cash, Cash Equivalents and Investments
Debt Instrument [Line Items]
Minimum liquidity requirement amount			13,000,000
White Oak Loan Agreement | Restricted Cash and Cash Equivalents
Debt Instrument [Line Items]
Minimum liquidity requirement amount			5,000,000
White Oak Loan Agreement | Accounts Receivable
Debt Instrument [Line Items]
Minimum liquidity requirement amount			2,000,000
White Oak Loan Agreement
Debt Instrument [Line Items]
Loan and security agreement			$ 33,000,000
Loan and security agreement, due date			Dec. 30, 2017
Capitalized debt issue costs			$ 1,500,000
Administration and monitoring fee			$ 32,000
Amortization of debt issuance costs				$ 400,000	$ 400,000	$ 100,000
Minimum liquidity requirement amount				15,000,000
White Oak Loan Agreement | Subsequent Event
Debt Instrument [Line Items]
Debt default, non-refundable transaction fee		$ 150,000
Repayments of secured debt	$ 5,000,000	$ 5,000,000
White Oak Loan Agreement | Cash, Cash Equivalents and Investments
Debt Instrument [Line Items]
Minimum liquidity requirement amount				13,000,000
White Oak Loan Agreement | Accounts Receivable
Debt Instrument [Line Items]
Minimum liquidity requirement amount				$ 2,000,000
Minimum liquidity requirement, percent of eligible accounts receivable			65.00%	65.00%
White Oak Loan Agreement | Interest Payment in Cash
Debt Instrument [Line Items]
Loan and security agreement, interest rate			11.00%
White Oak Loan Agreement | Payment in Kind (PIK)
Debt Instrument [Line Items]
Loan and security agreement, interest rate			3.00%
White Oak Loan Agreement | Payment to Lender Agent
Debt Instrument [Line Items]
Capitalized debt issue costs			$ 700,000
White Oak Loan Agreement | Payment to Placement Agent
Debt Instrument [Line Items]
Capitalized debt issue costs			$ 300,000
White Oak Loan Agreement | Principal Prepaid Before Third Anniversary
Debt Instrument [Line Items]
Prepayment fee of the principal			3.50%
White Oak Loan Agreement | Principal Prepaid After Third Anniversary
Debt Instrument [Line Items]
Prepayment fee of the principal			1.00%

Short-term and Long-term Debt54

Short-term and Long-term Debt - Future Annual Payments Due on Amounts Outstanding (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Debt Disclosure [Abstract]
2,016	$ 45,790
Total remaining payments	45,790
Less: Amount representing interest	(10,649)
Long-term debt, net, total	35,141
Less: Current portion of long-term debt	(35,141)	$ 0
Long-term debt, net of current portion	$ 0	$ 34,385

Restructuring (Details)

Restructuring (Details) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Nov. 30, 2015USD ($)employee	Dec. 31, 2015USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring expense		$ 1,700	$ 1,539	$ 0	$ 0
November 2015 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 1,700		1,727
November 2015 Restructuring Plan | Restructuring Expense
Restructuring Cost and Reserve [Line Items]
Restructuring expense	1,500
November 2015 Restructuring Plan | Cost of revenues
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 188
November 2015 Restructuring Plan | Operating Lease Cancellation
Restructuring Cost and Reserve [Line Items]
Restructuring expense			500
November 2015 Restructuring Plan | Exit Cost
Restructuring Cost and Reserve [Line Items]
Restructuring expense			$ 200
November 2015 Restructuring Plan | California
Restructuring Cost and Reserve [Line Items]
Number of positions eliminated | employee	35
November 2015 Restructuring Plan | California | Operating Lease Cancellation
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 500
November 2015 Restructuring Plan | International
Restructuring Cost and Reserve [Line Items]
Number of positions eliminated | employee	9
November 2015 Restructuring Plan | United Kingdom | Exit Cost
Restructuring Cost and Reserve [Line Items]
Restructuring expense	$ 200

Restructuring - Restructuring R

Restructuring - Restructuring Reserve (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Nov. 30, 2015	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Restructuring Reserve [Roll Forward]
Restructuring expense		$ 1,700	$ 1,539	$ 0	$ 0
November 2015 Restructuring Plan
Restructuring Reserve [Roll Forward]
Accrued restructuring balance as of January 1, 2015			0
Restructuring expense	$ 1,700		1,727
Cash payments			(146)
Accrued restructuring balance as of December 31, 2015		1,581	1,581	0
November 2015 Restructuring Plan | Employee Severance and Termination Benefits
Restructuring Reserve [Roll Forward]
Accrued restructuring balance as of January 1, 2015			0
Restructuring expense			1,027
Cash payments			(146)
Accrued restructuring balance as of December 31, 2015		881	881	0
November 2015 Restructuring Plan | Operating Lease Cancellation
Restructuring Reserve [Roll Forward]
Accrued restructuring balance as of January 1, 2015			0
Restructuring expense			500
Cash payments			0
Accrued restructuring balance as of December 31, 2015		500	500	0
November 2015 Restructuring Plan | Exit Cost
Restructuring Reserve [Roll Forward]
Accrued restructuring balance as of January 1, 2015			0
Restructuring expense			200
Cash payments			0
Accrued restructuring balance as of December 31, 2015		$ 200	$ 200	$ 0

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail)	May. 12, 2015USD ($)$ / sharesshares	Mar. 11, 2015USD ($)$ / sharesshares	Jul. 30, 2014USD ($)tranche$ / sharesshares	Jul. 30, 2013USD ($)series$ / sharesshares	Aug. 31, 2014USD ($)	Mar. 31, 2013USD ($)	Oct. 31, 2012shares	Jan. 31, 2010USD ($)	Jun. 30, 2015USD ($)	Mar. 31, 2014USD ($)shares	Dec. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2014USD ($)$ / sharesshares	Dec. 31, 2013USD ($)
Stockholders Equity Note [Line Items]
Maximum common stock offering amount under equity sale agreement						$ 25,000,000
Securities purchase agreement to sell shares | shares				2,845,528			529,101
Common stock per warrant price (in USD per share) | $ / shares				$ 12.3
Common Stock issuable upon exercise of warrants | shares		5,384,600		3,414,634
Common stock per warrant price (in USD per share) | $ / shares				$ 1.25
Number of series | series				3
Number of tranches | tranche			2
Proceeds from issuance of common stock and warrants				$ 39,300,000							$ 35,000,000	$ 0	$ 39,268,000
Placement fees and offering costs related to issuance of common stock and warrants				$ 2,100,000
Restricted period for resales of common stock				1 year
Gross proceed from exercise of warrants											0	37,100,000	0
Warrants exercise period		2 years
Warrant exchange and change in fair value of warrant liability									$ 2,900,000		$ 2,993,000	$ 2,914,000	0
Preferred stock, shares issued | shares		53,846									0	0
Preferred stock, par value (in USD per share) | $ / shares		$ 650									$ 0.0001	$ 0.0001
Conversion of shares, stock issued (in shares) | shares	5,509,492
Stock Conversion, price per share (in USD per share) | $ / shares		$ 0.65
Preferred stock dividend rate, percent		2.00%
Preferred stock dividend rate, percent increase									2.00%
Deemed dividend related to beneficial conversion feature of Series A convertible preferred stock and accretion of discount									$ 35,546,000		$ 35,546,000	$ 0	0
Cumulative dividend on Series A preferred stock									812,000		$ 812,000	0	$ 0
Deemed distribution due to allocation of discount									$ 15,300,000
Warrants exercise price (in USD per share) | $ / shares	$ 9.75	$ 9.75									$ 9.75
Premium on per share trailing weighted average share price		50.00%
Number of trading days		10 days
Warrant liability, reclassification to additional paid-in capital	$ 17,800,000										$ 17,800,000
Fair value of warrants upon issuance	$ 14,800,000	$ 14,800,000
Capitalized offering costs											500,000
Luna Innovations Incorporated
Stockholders Equity Note [Line Items]
Available-for-sale securities, other than temporary impairment recorded loss in other expense								$ 600,000			0	$ 0
Exchange Agreement
Stockholders Equity Note [Line Items]
Common Stock issuable upon exercise of warrants | shares			2,672,837
Series A Warrants
Stockholders Equity Note [Line Items]
Common Stock issuable upon exercise of warrants | shares				1,138,211
Common stock per warrant price (in USD per share) | $ / shares				$ 12.3
Number of warrants exercised | shares										1,100,000
Gross proceed from exercise of warrants										$ 14,000,000
Series B Warrant
Stockholders Equity Note [Line Items]
Common Stock issuable upon exercise of warrants | shares				1,138,211
Common stock per warrant price (in USD per share) | $ / shares				$ 15
Expiration date of warrants			August 2,015
Series B Warrant | Exchange Agreement
Stockholders Equity Note [Line Items]
Common Stock issuable upon exercise of warrants | shares			1,022,117
Series C Warrant
Stockholders Equity Note [Line Items]
Common Stock issuable upon exercise of warrants | shares				1,138,211
Common stock per warrant price (in USD per share) | $ / shares				$ 20
Expiration date of warrants			August 2,015
Series C Warrant | Exchange Agreement
Stockholders Equity Note [Line Items]
Common Stock issuable upon exercise of warrants | shares			1,022,117
Series B/C Exchange Warrants | Exchange Agreement
Stockholders Equity Note [Line Items]
Common Stock issuable upon exercise of warrants | shares			2,044,235
Common stock per warrant price (in USD per share) | $ / shares			$ 11.3
Gross proceed from exercise of warrants					$ 23,100,000
Period at which warrants subject to mandatory exercise after issuance			14 days
Series D Warrants | Exchange Agreement
Stockholders Equity Note [Line Items]
Common Stock issuable upon exercise of warrants | shares			628,602
Common stock per warrant price (in USD per share) | $ / shares			$ 1.13
Gross proceed from exercise of warrants			$ 7,100,000
Warrants exercise period			5 years
Other income (expense)
Stockholders Equity Note [Line Items]
Warrant exchange and change in fair value of warrant liability											$ 3,000,000

Stockholders' Equity - Componen

Stockholders' Equity - Component of Accumulated Other Comprehensive Income (Loss), Net of Tax (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	$ 305	$ 360
Change in other comprehensive income (loss)	(515)	(55)	$ 938
Accumulated other comprehensive income (loss), ending balance	(210)	305	360
Unrealized Gains (Losses) on Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	392	373
Change in other comprehensive income (loss)	(464)	19
Accumulated other comprehensive income (loss), ending balance	(72)	392	373
Foreign Currency Translation Gains (Losses)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(87)	(13)
Change in other comprehensive income (loss)	(51)	(74)
Accumulated other comprehensive income (loss), ending balance	$ (138)	$ (87)	$ (13)

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail)	Sep. 22, 2015shares	May. 12, 2015	Dec. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2014USD ($)$ / sharesshares	Dec. 31, 2013USD ($)$ / shares	Sep. 21, 2015shares	Dec. 31, 2012USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock split conversion ratio	0.1	0.10
Common stock, shares authorized	30,000,000		30,000,000	30,000,000		300,000,000
Number of unvested shares outstanding			0
Percentage of common shares outstanding			4.00%
Weighted-average grant-date fair value of options granted (in USD per share) | $ / shares			$ 5.11	$ 6.22	$ 12.49
Total fair value of options vested | $			$ 1,600,000	$ 1,900,000	$ 2,600,000
Total unamortized stock-based compensation related to unvested stock options | $			$ 1,600,000
Weighted-average recognition period, unvested stock options			2 years 2 months
Total intrinsic value of stock options exercised | $				2,000	600,000		$ 19,000
Stock-based compensation | $			$ 2,758,000	$ 2,832,000	4,889,000
Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock Units, Awarded				41,407
Period after year end to measure financial performance targets			30 days
Restricted Stock Units, Cancelled			22,388
Stock-based compensation | $			$ 0
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employees to contribute, Percent			15.00%
Employees to contribute, Amount | $			$ 25,000
Maximum range of company's board of directors offerings			27 months
Percentage of fair market value of share for participated by employee			85.00%
Company initially reserved			62,500
Percentage of share outstanding for automatic increase in share reserve for issuance			2.00%
Number of share increase in share reserve for issuance			75,000
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average recognition period, unvested stock options			2 years 8 months
Total fair value of shares vested pursuant to restricted stock units | $			$ 2,600,000	$ 2,500,000	$ 2,600,000
Unamortized stock-based compensation related to unvested restricted stock units | $			$ 1,000,000
Restricted Stock Units, Awarded			568,000
Restricted Stock Units, Cancelled			138,000
Performance Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of award			1 year
Restricted Stock Units, Awarded			318,721
Number of shares received per each PSU upon vesting			1
Grant date aggregate fair value of awards granted | $			$ 2,900,000
Stock-based compensation | $			$ 800,000
2002 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock for issuance under its stock option plan, initial reserve			457,901
Share-based compensation arrangement by share-based payment award, expiration period maximum			10 years
2006 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock for issuance under its stock option plan, initial reserve			200,000
Share-based compensation arrangement by share-based payment award, expiration period maximum			10 years
Equity Incentive Plan automatically increases by total number of share outstanding			350,000
Shares of common stock were available for grant under 2006 Equity Incentive Plan			336,642
First anniversary of vesting start date | 2002 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercises of employee options on the first anniversary			25.00%
Thereafter | 2002 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of award			36 months

Stock-based Compensation - Summ

Stock-based Compensation - Summary of Option Activity Under 2002 Plan and 2006 Plan (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Options Outstanding
Balance at January 1, 2015 (in shares)	919
Granted (in shares)	91
Exercised (in shares)	(1)
Cancelled (in shares)	(219)
Balance at December 31, 2015 (in shares)	790	919
Options vested and expected to vest at December 31, 2015 (in shares)	673
Options vested at December 31, 2015 (in shares)	361
Weighted- Average Exercise Price
Balance at January 1, 2015 (in USD per share)	$ 16.88
Granted (in USD per share)	9.18
Exercised (in USD per share)	5.23
Cancelled (in USD per share)	24.06
Balance at December 31, 2015 (in USD per share)	14.08	$ 16.88
Options vested and expected to vest at December 31, 2015 (in USD per share)	14.56
Options vested at December 31, 2015 (in USD per share)	$ 19.49
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted- Average Remaining Contractual Term, Balance	7 years 4 months 24 days	7 years 9 months 18 days
Weighted- Average Remaining Contractual Term, Options vested and expected to vest at December 31, 2015	6 years
Weighted- Average Remaining Contractual Term, Options vested at December 31, 2015	7 years 2 months 12 days
Aggregate Intrinsic Value, Beginning Balance	$ 0
Aggregate Intrinsic Value, Exercised	2
Aggregate Intrinsic Value, Cancelled	23
Aggregate Intrinsic Value, Ending Balance	0	$ 0
Aggregate Intrinsic Value, Options vested and expected to vest at December 31, 2015	0
Aggregate Intrinsic Value, Options vested at December 31, 2015	$ 0

Stock-based Compensation - Assu

Stock-based Compensation - Assumptions Used to Estimate Grant Date Fair Values of Stock Options (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock Options
Estimated grant date fair values
Expected volatility	73.00%	73.00%
Expected volatility, minimum		77.00%
Expected volatility, maximum		89.00%
Risk-free interest rate	1.30%	1.40%
Risk-free interest rate, minimum		0.60%
Risk-free interest rate, maximum		1.50%
Expected term (in years)	4 years 1 month 16 days	4 years 3 months 22 days
Dividend yield	0.00%	0.00%	0.00%
Stock Options | Minimum
Estimated grant date fair values
Expected term (in years)		4 years 4 months 17 days
Stock Options | Maximum
Estimated grant date fair values
Expected term (in years)		4 years 6 months 26 days
Employee Stock Purchase Plan
Estimated grant date fair values
Expected volatility	78.00%	111.00%	65.00%
Risk-free interest rate	0.10%	0.10%	0.10%
Expected term (in years)	6 months	6 months	6 months
Dividend yield	0.00%	0.00%	0.00%

Stock-based Compensation - Opti

Stock-based Compensation - Options outstanding, vested and currently exercisable by exercise price under both the 2002 Plan and the 2006 Plan (Detail) shares in Thousands	12 Months Ended
	Dec. 31, 2015$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding, Number of Options (in shares) | shares	790
Options Outstanding, Weighted-Average Remaining Contractual Life	7 years 4 months 28 days
Options Exercisable and Vested, Number of Options (in shares) | shares	361
Options Exercisable and Vested, Weighted-Average Exercise Price (in USD per share)	$ 19.49
Options Exercisable and Vested, Weighted- Average Remaining Contractual Life	6 years 7 days
$6.45-$6.48
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding, Exercise Price, Lower Limit	$ 6.45
Options Outstanding, Exercise Price, Upper Limit	$ 6.48
Options Outstanding, Number of Options (in shares) | shares	145
Options Outstanding, Weighted-Average Remaining Contractual Life	8 years 11 months 8 days
Options Exercisable and Vested, Number of Options (in shares) | shares	0
Options Exercisable and Vested, Weighted-Average Exercise Price (in USD per share)	$ 0
Options Exercisable and Vested, Weighted- Average Remaining Contractual Life	0 years
$6.49-$9.18
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding, Exercise Price, Lower Limit	$ 6.49
Options Outstanding, Exercise Price, Upper Limit	$ 9.18
Options Outstanding, Number of Options (in shares) | shares	214
Options Outstanding, Weighted-Average Remaining Contractual Life	9 years 11 days
Options Exercisable and Vested, Number of Options (in shares) | shares	65
Options Exercisable and Vested, Weighted-Average Exercise Price (in USD per share)	$ 7.69
Options Exercisable and Vested, Weighted- Average Remaining Contractual Life	9 years 1 month 2 days
$9.19-$20.75
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding, Exercise Price, Lower Limit	$ 9.19
Options Outstanding, Exercise Price, Upper Limit	$ 20.75
Options Outstanding, Number of Options (in shares) | shares	206
Options Outstanding, Weighted-Average Remaining Contractual Life	7 years 5 months 12 days
Options Exercisable and Vested, Number of Options (in shares) | shares	107
Options Exercisable and Vested, Weighted-Average Exercise Price (in USD per share)	$ 14.79
Options Exercisable and Vested, Weighted- Average Remaining Contractual Life	6 years 7 months 6 days
$20.76-$77.60
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding, Exercise Price, Lower Limit	$ 20.76
Options Outstanding, Exercise Price, Upper Limit	$ 77.60
Options Outstanding, Number of Options (in shares) | shares	225
Options Outstanding, Weighted-Average Remaining Contractual Life	4 years 9 months 29 days
Options Exercisable and Vested, Number of Options (in shares) | shares	189
Options Exercisable and Vested, Weighted-Average Exercise Price (in USD per share)	$ 26.24
Options Exercisable and Vested, Weighted- Average Remaining Contractual Life	4 years 7 months 13 days

Stock-based Compensation - Su63

Stock-based Compensation - Summary of Restricted Stock Unit Activity (Detail) - Restricted Stock Units (RSUs) shares in Thousands	12 Months Ended
	Dec. 31, 2015$ / sharesshares
Restricted Stock Outstanding [Rollforward]
Balance at January 1, 2015 (in shares) | shares	84
Awarded (in shares) | shares	568
Vested (in shares) | shares	(29)
Cancelled (in shares) | shares	(138)
Balance at December 31, 2015 (in shares) | shares	485
Weighted- Average Grant- Date Fair Value
Balance at January 1, 2015 (in USD per share) | $ / shares	$ 18.02
Awarded (in USD per share) | $ / shares	8.93
Vested (in USD per share) | $ / shares	14.18
Cancelled (in USD per share) | $ / shares	11.14
Balance at December 31, 2015 (in USD per share) | $ / shares	$ 9.57

Stock-based Compensation - Tota

Stock-based Compensation - Total Stock-Based Compensation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation	$ 2,758	$ 2,832	$ 4,889
Cost of revenues
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation	233	230	402
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation	632	704	1,320
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation	$ 1,893	$ 1,898	$ 3,167

Income Taxes - Summary of Compa

Income Taxes - Summary of Company's Pre Tax Loss (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Domestic	$ (46,382)	$ (54,457)	$ (55,877)
Foreign	222	239	270
Pre-tax loss	$ (46,160)	$ (54,218)	$ (55,607)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Mar. 11, 2015	Jul. 30, 2013
Income Tax Disclosure [Line Items]
Foreign Taxes	$ 47,000
Tax credit carryforwards	$ 4,193,000	$ 10,564,000
Percentage of valuation allowance against net deferred tax assets	100.00%
Increase in valuation allowance	$ (69,600,000)	$ 17,100,000	$ 21,400,000
Ownership change occurrence from percentage of corporation owned increases by specified percentage	5.00%
Percentage increase over minimum percentage of corporation owned shares	50.00%
Number of years considered in ownership change occurrence	3 years
Common Stock issuable upon exercise of warrants				5,384,600	3,414,634
Cumulative foreign earnings upon which U.S. income taxes have not been provided	$ 800,000
Unrecognized benefit that none affect Company's effective tax rate	2,100,000
Accrued interest or penalties related to uncertain tax positions	0
Stock Options
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	1,900,000
Federal
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	117,100,000
Tax credit carryforwards	$ 200,000
Tax credit carryforwards expiration year	2,035
State
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 125,300,000
State | California
Income Tax Disclosure [Line Items]
Tax credit carryforwards	$ 8,200,000

Income Taxes - Effective Tax Ra

Income Taxes - Effective Tax Rate Differs From Federal Statutory Rate (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Summary of company's effective tax rate differs from the U.S. federal statutory rate
Federal tax benefit at statutory rate	(34.00%)	(34.00%)	(34.00%)
Permanent difference due to non-deductible expenses	3.00%	2.00%	1.00%
State tax benefit, net of federal impact	0.00%	0.00%	0.00%
Change in deferred tax asset valuation allowance	31.00%	33.00%	33.00%
General business credits	(0.00%)	(1.00%)	(0.00%)
Effective tax rate	0.00%	0.00%	0.00%

Income Taxes - Significant Port

Income Taxes - Significant Portions of the Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 46,942	$ 108,245
Research and development credits	4,193	10,564
Capitalized research and development	19,803	19,926
Fixed assets	2,243	2,464
Stock-based compensation	1,442	3,214
Accruals, reserves and other	2,637	2,259
Intangibles	694	857
Gross deferred tax asset	77,954	147,529
Less: Valuation allowance	(77,954)	(147,529)
Net deferred tax asset	$ 0	$ 0

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of the Beginning and Ending Balance of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of the beginning and ending balance of unrecognized tax benefits
Balance at beginning of period	$ 4,220	$ 3,864	$ 3,358
Additions based on tax positions related to the current year	165	384	301
Additions based on tax positions related to prior years	(2,287)	(28)	205
Balance at end of period	$ 2,098	$ 4,220	$ 3,864

Net Loss per Share - Computatio

Net Loss per Share - Computation of Basic and Diluted Net Income (Loss) per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Computation of basic and diluted net income (loss) per share
Net loss		$ (11,540)	$ (10,227)	$ (12,507)	$ (11,933)	$ (11,917)	$ (15,594)	$ (12,290)	$ (14,445)	$ (46,207)		$ (54,246)		$ (55,722)
Deemed dividend related to beneficial conversion feature of Series A convertible preferred stock and accretion of discount				(35,546)						(35,546)		0		0
Cumulative dividend on Series A convertible preferred stock				(812)						(812)		0		0
Net loss attributable to common stockholders		$ (11,540)	$ (10,227)	$ (48,865)	$ (11,933)					$ (82,565)		$ (54,246)		$ (55,722)
Shares used to calculated basic and diluted net loss per share	[1]									16,871		11,723		7,905
Basic and diluted net loss per share (in USD per share)		$ (0.61)	$ (0.54)	$ (3)	$ (0.90)	$ (0.90)	$ (1.30)	$ (1.10)	$ (1.40)	$ (4.89)	[1]	$ (4.63)	[1]	$ (7.05)	[1]
[1]	The Company’s financial statements have been retroactively adjusted to reflect the reverse stock split of its outstanding shares of common stock at a ratio of one-for-ten effective on September 22, 2015.

Net Loss per Share - Securities

Net Loss per Share - Securities That could Potentially Dilute Basic Net Loss Per Share Not Included In Calculation of Diluted Net Loss per Share (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	790	919	778
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	485	84	132
Estimated shares issuable under the employee stock purchase plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	3	13	4
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	6,079	927	3,481

Segment Information - Additiona

Segment Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2015Segment
Segment Reporting [Abstract]
Number of operating segments	1

Segment Information - Informati

Segment Information - Information Regarding Total Revenue (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue, Major Customer [Line Items]
Revenues	$ 3,999	$ 3,183	$ 3,092	$ 5,794	$ 5,032	$ 3,877	$ 6,887	$ 3,699	$ 16,068	$ 19,495	$ 16,982
United States
Revenue, Major Customer [Line Items]
Revenues									7,124	10,041	8,580
International
Revenue, Major Customer [Line Items]
Revenues									$ 8,944	$ 9,454	$ 8,402

Segment Information - Informa74

Segment Information - Information Regarding Total Revenue (Narrative) (Detail) - Geographic Concentration Risk - Sales - location	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Italy
Revenue, Major Customer [Line Items]
Concentration risk, percentage	11.00%
Belgium
Revenue, Major Customer [Line Items]
Concentration risk, percentage	10.00%
Japan
Revenue, Major Customer [Line Items]
Concentration risk, percentage		13.00%
International
Revenue, Major Customer [Line Items]
Concentration risk, number of locations			0

Quarterly Data (unaudited) (Det

Quarterly Data (unaudited) (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Summary of certain unaudited quarterly information for the eight quarters
Revenues	$ 3,999	$ 3,183	$ 3,092	$ 5,794	$ 5,032	$ 3,877	$ 6,887	$ 3,699	$ 16,068		$ 19,495		$ 16,982
Gross profit	(715)	204	358	1,156	2	702	1,902	398	1,003		3,004		3,501
Net loss	(11,540)	(10,227)	(12,507)	(11,933)	$ (11,917)	$ (15,594)	$ (12,290)	$ (14,445)	(46,207)		(54,246)		(55,722)
Net loss attributable to common stockholders	$ (11,540)	$ (10,227)	$ (48,865)	$ (11,933)					$ (82,565)		$ (54,246)		$ (55,722)
Basic and diluted net loss per share (in USD per share)	$ (0.61)	$ (0.54)	$ (3)	$ (0.90)	$ (0.90)	$ (1.30)	$ (1.10)	$ (1.40)	$ (4.89)	[1]	$ (4.63)	[1]	$ (7.05)	[1]
[1]	The Company’s financial statements have been retroactively adjusted to reflect the reverse stock split of its outstanding shares of common stock at a ratio of one-for-ten effective on September 22, 2015.

Quarterly Data (unaudited) (Nar

Quarterly Data (unaudited) (Narrative) (Detail) $ in Thousands	Sep. 22, 2015	May. 12, 2015	Dec. 31, 2015USD ($)	Jun. 30, 2015USD ($)	Sep. 30, 2014USD ($)	Mar. 31, 2013USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Quarterly Financial Information Disclosure [Abstract]
Stock split conversion ratio	0.1	0.10
Warrant exchange and change in fair value of warrant liability				$ 2,900			$ 2,993	$ 2,914	$ 0
Deemed dividend related to beneficial conversion feature of Series A convertible preferred stock and accretion of discount				35,546			35,546	0	0
Cumulative dividend on Series A convertible preferred stock				812			812	0	0
Deemed distribution due to allocation of discount				$ 15,300
Restructuring expense			$ 1,700				1,539	0	0
Gain (loss) on settlement of litigation					$ (2,900)	$ (4,500)	$ 0	$ 0	$ (4,500)

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Apr. 20, 2016	Apr. 19, 2016	Dec. 31, 2015
Convertible Preferred Stock
Subsequent Event [Line Items]
Preferred stock issued			$ 19,678
Subsequent Event
Subsequent Event [Line Items]
Shareholders agreeing to stock purchase agreement, percent of outstanding common stock	64.60%
Subsequent Event | White Oak Loan Agreement
Subsequent Event [Line Items]
Repayments of secured debt	$ 5,000	$ 5,000
Subsequent Event | Auris Surgical Robotics, Inc | Convertible Preferred Stock
Subsequent Event [Line Items]
Preferred stock issued	$ 49,000
Subsequent Event | Restricted Stock Units (RSUs)
Subsequent Event [Line Items]
Percent of performance conditions met	100.00%
Subsequent Event | Scenario, Forecast | Merger with Auris Surgical Robotics, Inc
Subsequent Event [Line Items]
Business acquisition, price per share (in USD per share)	$ 4
Termination fee	$ 3,325
Percent of outstanding shares approving merger	65.40%