Penumbra (PEN) 10-Q 12 Nov 15 2015 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document - shares	9 Months Ended
	Sep. 30, 2015	Oct. 31, 2015
Document and Entity Information [Abstract]
Entity Registrant Name	Penumbra Inc
Entity Central Index Key	1,321,732
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		29,889,955

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 159,098	$ 3,290
Marketable investments	0	48,253
Accounts receivable, net of doubtful accounts of $494 and $602	26,055	18,912
Inventories	50,324	33,451
Deferred taxes	7,333	6,280
Prepaid expenses and other current assets	6,267	5,115
Total current assets	249,077	115,301
Property and equipment, net	8,646	5,181
Deferred taxes	1,309	571
Other non-current assets	293	328
Total assets	259,325	121,381
Current Liabilities:
Accounts payable	4,024	2,348
Accrued liabilities	24,253	18,475
Total current liabilities	28,277	20,823
Other non-current liabilities	2,458	1,461
Total liabilities	$ 30,735	$ 22,284
Commitments and contingencies
Convertible preferred stock, $0.001 par value per share—none authorized, issued and outstanding at September 30, 2015; 25,000,000 shares authorized, 19,510,410 shares issued and outstanding at December 31, 2014; aggregate liquidation value $149,361 at December 31, 2014	$ 0	$ 111,467
Stockholders’ Equity (Deficit):
Preferred stock, $0.001 par value per share—5,000,000 shares authorized, none issued and outstanding at September 30, 2015; None authorized, issued and outstanding at December 31, 2014	0	0
Common stock, $0.001 par value per share—300,000,000 shares authorized, 29,882,621 issued and outstanding at September 30, 2015; 40,000,000 shares authorized, 4,736,689 issued and outstanding at December 31, 2014	30	5
Additional paid-in capital	249,230	8,446
Notes receivable from stockholders	(26)	(117)
Accumulated other comprehensive loss	(1,536)	(864)
Accumulated deficit	(19,108)	(19,840)
Total stockholders’ equity (deficit)	228,590	(12,370)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$ 259,325	$ 121,381

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 494	$ 602
Convertible preferred stock, par value (in dollars per share)		$ 0.001
Convertible preferred stock, shares authorized	0	25,000,000
Convertible preferred stock, shares issued	0	19,510,410
Convertible preferred stock, shares outstanding	0	19,510,410
Convertible preferred stock, aggregate liquidation amount		$ 149,361
Preferred stock, par value (in dollars per share)	$ 0.001
Preferred stock, shares authorized	5,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	300,000,000	40,000,000
Common stock, shares issued	29,882,621	4,736,689
Common stock, shares outstanding	29,882,621	4,736,689

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
Revenue	$ 50,416	$ 32,464	$ 131,679	$ 90,107
Cost of revenue	16,919	11,667	44,079	31,156
Gross profit	33,497	20,797	87,600	58,951
Operating expenses:
Research and development	4,560	3,897	12,543	11,435
Sales, general and administrative	26,755	16,589	72,698	44,829
Total operating expenses	31,315	20,486	85,241	56,264
Income from operations	2,182	311	2,359	2,687
Interest income (expense), net	17	144	402	183
Other income (expense), net	(115)	(56)	(613)	(148)
Income before provision for income taxes	2,084	399	2,148	2,722
Provision for income taxes	1,183	227	1,416	893
Net income	901	172	732	1,829
Foreign currency translation adjustments, net of tax	(303)	(413)	(892)	(507)
Unrealized gains (losses) on available-for-sale securities, net of tax	0	(266)	220	(92)
Comprehensive income (loss)	598	(507)	60	1,230
Net income (loss) attributable to common stockholders	$ 276	$ (1,192)	$ 175	$ (933)
Net income (loss) per share attributable to common stockholders — Basic (in dollars per share)	$ 0.04	$ (0.25)	$ 0.03	$ (0.20)
Net income (loss) per share attributable to common stockholders — Diluted (in dollars per share)	$ 0.03	$ (0.25)	$ 0.02	$ (0.20)
Weighted average shares used to compute net income (loss) per share attributable to common stockholders — Basic	7,853,730	4,688,045	5,962,031	4,577,725
Weighted average shares used to compute net income (loss) per share attributable to common stockholders — Diluted	10,189,248	4,688,045	8,494,651	4,577,725

Condensed Consolidated Stateme5

Condensed Consolidated Statement of Convertible Preferred Stock and Stockholders’ Equity (Deficit) (Unaudited) - 9 months ended Sep. 30, 2015 - USD ($) $ in Thousands	Total	Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Notes Receivable from Stockholders	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance at Dec. 31, 2014	$ 111,467	$ 111,467
Beginning balance, shares at Dec. 31, 2014	19,510,410	19,510,410
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of convertible preferred stock into common stock upon closing of IPO		$ (111,467)
Conversion of convertible preferred stock into common stock upon closing of IPO, shares		(19,510,410)
Ending balance at Sep. 30, 2015	$ 0	$ 0
Ending balance, shares at Sep. 30, 2015	0	0
Beginning balance at Dec. 31, 2014	$ (12,370)		$ 5	$ 8,446	$ (117)	$ (864)	$ (19,840)
Beginning balance, shares at Dec. 31, 2014			4,736,689
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of convertible preferred stock into common stock upon closing of IPO	111,467		$ 19	111,448
Conversion of convertible preferred stock into common stock upon closing of IPO, shares			19,510,410
Shares issued upon closing of IPO	124,767		$ 5	124,762
Shares issued upon closing of IPO, shares			4,600,000
Issuance of common stock, shares	1,059		$ 1	1,058
Issuance of common stock, shares			1,059,172
Shares held for tax withholdings	(2,525)			(2,525)
Repurchase of common stock	(342)			(342)
Repurchase of common stock, shares			(23,650)
Stock-based compensation	5,126			5,126
Excess tax benefit from stock-based compensation	1,257			1,257
Forgiven notes receivable from stockholders	91				91
Foreign currency translation adjustment, net of tax of $116	(892)					(892)
Unrealized gain on investments, net of tax of $159	220					220
Net income	732						732
Ending balance at Sep. 30, 2015	$ 228,590		$ 30	$ 249,230	$ (26)	$ (1,536)	$ (19,108)
Ending balance, shares at Sep. 30, 2015			29,882,621

Condensed Consolidated Stateme6

Condensed Consolidated Statement of Convertible Preferred Stock and Stockholders’ Equity (Deficit) (Unaudited) (Parenthetical) $ in Thousands	9 Months Ended
	Sep. 30, 2015USD ($)
Statement of Stockholders' Equity [Abstract]
Foreign currency translation adjustment, tax	$ 116
Unrealized gain on investments, tax	$ 159

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 732	$ 1,829
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	1,227	520
Stock-based compensation	5,126	1,074
Excess tax benefit from stock-based compensation	(1,257)	0
Provision for doubtful accounts	(108)	172
Inventory write downs	704	1,398
Write off of note receivable	91	0
Provision for sales returns	675	122
Loss on minority investment	0	150
Loss on disposal of property and equipment	12	30
Realized loss on marketable investments	541	0
Provision for product warranty	299	26
Changes in operating assets and liabilities:
Accounts receivable	(7,383)	(4,971)
Inventories	(18,012)	(5,157)
Prepaid expenses and other current and non-current assets	(1,706)	(207)
Accounts payable	1,501	888
Accrued expenses and other non-current liabilities	4,927	3,133
Net cash used in operating activities	(12,631)	(993)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of marketable investments	(4,069)	(48,771)
Proceeds from sales of marketable investments	52,160	12,737
Purchases of property and equipment	(4,507)	(1,798)
Net cash provided by (used in) investing activities	43,584	(37,832)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of preferred stock, net of issuance costs	0	57,212
Proceeds from issuance of common stock issued in initial public offering, net of issuance costs	125,916	0
Proceeds from exercises of stock options	546	923
Excess tax benefit from stock-based compensation	1,257	0
Repurchase of preferred stock	0	(8,311)
Repayment of credit facility	0	(6,000)
Repurchase of common stock and stock options	0	(1,022)
Payment of employee taxes related to vested common and restricted stock	(2,525)	0
Net cash provided by financing activities	125,194	42,802
Effect of foreign exchange rate changes on cash and cash equivalents	(339)	80
Net Increase In Cash And Cash Equivalents	155,808	4,057
CASH AND CASH EQUIVALENTS—Beginning of period	3,290	4,131
CASH AND CASH EQUIVALENTS—End of period	159,098	8,188
NONCASH INVESTING AND FINANCING ACTIVITIES:
Conversion of convertible preferred stock into common stock	111,467	0
Purchase of property and equipment funded through accounts payable	200	85
Deferred issuance costs not yet paid	$ 1,149	$ 0

Organization and Description of

Organization and Description of Business	9 Months Ended
	Sep. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	Organization and Description of Business Penumbra, Inc. (the “Company”) is a global interventional therapies company that designs, develops, manufactures and markets innovative medical devices. The Company has a broad portfolio of products that addresses challenging medical conditions and significant clinical needs across two major markets, neuro and peripheral vascular. The conditions that the Company’s products address include, among others, ischemic stroke, hemorrhagic stroke and various peripheral vascular conditions that can be treated through thrombectomy and embolization procedures.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation and Consolidation The accompanying interim condensed consolidated balance sheet as of September 30, 2015 , the interim condensed consolidated statements of operations for the three and nine months ended September 30, 2015 and 2014 , the interim condensed consolidated statement of preferred stock and stockholders’ equity (deficit) for the nine months ended September 30, 2015 , and the interim condensed consolidated statements of cash flows for the nine months ended September 30, 2015 and 2014 are unaudited. The unaudited interim condensed consolidated financial statements included herein have been prepared by the Company in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and the applicable rules and regulations of the Securities and Exchange Commission (“SEC”) for interim financial information. Accordingly, they do not include all of the information and notes required by U.S. GAAP for complete financial statements. The December 31, 2014 condensed consolidated balance sheet was derived from the audited financial statements as of that date, but does not include all of the information and footnotes required by GAAP for complete financial statements. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements and, in the opinion of management, reflect all adjustments of a normal recurring nature considered necessary to state fairly the Company’s financial position as of September 30, 2015 and results of its operations for the three and nine months ended September 30, 2015 and 2014 , and the cash flows for the nine months ended September 30, 2015 and 2014 . The interim results for the nine months ended September 30, 2015 are not necessarily indicative of the results that may be expected for the year ending December 31, 2015 or for any other future annual or interim period. The information included in this quarterly report on Form 10-Q should be read in conjunction with the financial statements and notes thereto contained in the Company’s Prospectus dated September 17, 2015 as filed by the Company with the SEC pursuant to Rule 424(b)(4) under the Securities Act of 1933, as amended, relating to the Company’s Registration Statement on Form S-1 (“Prospectus”) (File No. 333-206412). The condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities and equity accounts; disclosure of contingent assets and liabilities at the date of the financial statements; and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates, including those related to provisions for doubtful accounts, sales return reserve, warranty reserves, valuation of inventories, useful lives of property and equipment, income taxes, the valuation of equity instruments and contingencies, among others. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other data. Actual results could differ from those estimates. Segments The Company determined its operating segment on the same basis that it uses to evaluate its performance internally. The Company has one business activity: the design, development, manufacturing and marketing of innovative medical devices, and operates as one operating segment. The Company’s chief operating decision-maker, its Chief Executive Officer, reviews its operating results for the purpose of allocating resources and evaluating financial performance. The Company determines revenue by geographic area, based on the destination to which it ships its products. Foreign Currency Translation The Company’s condensed consolidated financial statements are prepared in United States Dollars (USD). Its foreign subsidiaries use their local currency as their functional currency and maintain their records in the local currency. Accordingly, the assets and liabilities of these subsidiaries are translated into USD using the current exchange rates in effect at the balance sheet date and equity accounts are translated into USD using historical rates. Revenues and expenses are translated using the average exchange rates in effect. The resulting foreign currency translation adjustments are recorded in other comprehensive income in the condensed consolidated balance sheets. Transactions denominated in foreign currency are translated at exchange rates at the date of transaction with foreign currency gains (losses) recorded in other income (expense), net in the condensed consolidated statements of operations and other comprehensive income. The Company recognized net foreign currency transaction gains of $0.1 million and $0.1 million during the three months ended September 30, 2015 and 2014 , respectively, and $11,000 and $0.2 million during the nine months ended September 30, 2015 and 2014 , respectively. As the Company’s international operations grow, its risks associated with fluctuation in currency rates will become greater, and the Company will continue to reassess its approach to managing this risk. In addition, currency fluctuations or a weakening USD can increase the costs of the Company’s international expansion. To date, the Company has not entered into any foreign currency hedging contracts, since exchange rate fluctuations have not had a material impact on its operating results and cash flows. Concentration of Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash and cash equivalents, marketable investments and accounts receivable. The majority of the Company’s cash is held by one financial institution in the United States in excess of federally insured limits. The Company maintained investments in money market funds that were not federally insured during the year ended December 31, 2014 and held cash in foreign banks of approximately $2.3 million and $0.8 million at September 30, 2015 and December 31, 2014 , respectively, that was not federally insured. The Company has not experienced any losses on its deposits of cash and cash equivalents. All of the Company’s revenue has been derived from sales of its products in the United States and international markets. The Company uses both its own salesforce and independent distributors to sell its products. Concentrations of credit risk with respect to accounts receivable are limited due to the large number of entities comprising the Company’s customer base. The Company performs ongoing credit evaluations of its customers, including its distributors, does not require collateral, and maintains allowances for potential credit losses on customer accounts when deemed necessary. One customer (a distributor) accounted for 11% and 11% , respectively, of the Company’s revenue during the three months ended September 30, 2015 and 2014 . The same customer accounted for 11% and 12% , respectively, of the Company’s revenue during the nine months ended September 30, 2015 and 2014 . No customer accounted for greater than 10% of the Company’s accounts receivable balance as of September 30, 2015 or December 31, 2014 . Significant Risks and Uncertainties The Company is subject to risks common to medical device companies including, but not limited to, new technological innovations, dependence on key personnel, protection of proprietary technology, compliance with government regulations, product liability, uncertainty of market acceptance of products and the potential need to obtain additional financing. The Company is dependent on third party suppliers, in some cases single-source suppliers. There can be no assurance that the Company’s products will continue to be accepted in the marketplace, nor can there be any assurance that any future products can be developed or manufactured at an acceptable cost and with appropriate performance characteristics, or that such products will be successfully marketed, if at all. The Company’s products require approval or clearance from the U.S. Food and Drug Administration prior to commencing commercial sales in the United States. There can be no assurance that the Company’s products will receive all of the required approvals or clearances. Approvals or clearances are also required in foreign jurisdictions in which the Company sells its products. If the Company is denied such approvals or clearances or such approvals or clearances are delayed, it may have a material adverse impact on the Company’s results of operations, financial position and liquidity. Fair Value of Financial Instruments Carrying amounts of certain of the Company’s financial instruments, including cash equivalents, accounts receivable, prepaid expenses and other current assets, accounts payable and accrued liabilities, approximate fair value due to their relatively short maturities. Cash, Cash Equivalents and Marketable Investments The Company invests its cash primarily in money market funds and in highly liquid debt instruments of U.S. federal and municipal governments and their agencies and corporate debt securities. All highly liquid investments with stated maturities of three months or less from the date of purchase are classified as cash equivalents; all highly liquid investments with stated maturities of greater than three months are classified as marketable investments. The majority of the Company’s cash and investments are held in U.S. banks. The Company determines the appropriate classification of its investments in marketable investments at the time of purchase and re-evaluates such designation at each balance sheet date. The Company’s marketable investments have been classified and accounted for as available-for-sale. Investments with remaining maturities of more than one year are viewed by the Company as available to support current operations and are classified as current assets under the caption marketable investments in the accompanying condensed consolidated balance sheets. Investments in marketable investments are carried at fair value, with the unrealized gains and losses reported as a component of accumulated other comprehensive loss. Any realized gains or losses on the sale of marketable investments are determined on a specific identification method, and such gains and losses are reflected as a component of other income (expense), net. Impairment of Marketable Investments After determining the fair value of available-for-sale debt instruments, gains or losses on these securities are recorded to accumulated other comprehensive income (loss) until either the security is sold or the Company determines that the decline in value is other-than-temporary. The primary differentiating factors that the Company considers in classifying impairments as either temporary or other-than-temporary impairments is the intent and ability to retain the 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. There were no other-than-temporary impairments for the three or nine months ended September 30, 2015 and 2014 . The Company did not have any marketable investments as of September 30, 2015 . Accounts Receivable Accounts receivable are stated at invoice value less estimated allowances for doubtful accounts. The Company continually monitors customer payments and maintains a reserve for estimated losses resulting from its customers’ inability to make required payments. The Company considers factors such as historical experience, credit quality, age of the accounts receivable balances, geographic related risks and economic conditions that may affect a customer’s ability to pay. In cases where there are circumstances that may impair a specific customer’s ability to meet its financial obligations, a specific allowance is recorded against amounts due, and thereby reduces the net recognized receivable to the amount reasonably believed to be collectible. Inventories Inventories are stated at the lower of cost (determined under the first-in first-out method) or market. Write downs are provided for raw materials, components or finished goods that are determined to be excessive or obsolete. Market value is determined as the lower of replacement cost or net realizable value. The Company regularly reviews inventory quantities in consideration of actual loss experience, projected future demand and remaining shelf life to record a provision for excess and obsolete inventory when appropriate. The estimate of excess quantities is subjective and primarily dependent on the Company’s estimates of future demand for a particular product or components or raw materials used in the manufacturing of such product. If the estimate of future demand is inaccurate based on actual sales, the Company may increase the write down for excess inventory and record a charge to inventory impairment in the accompanying condensed consolidated statements of operations and comprehensive income. The Company periodically evaluates the carrying value of inventory on hand for potential excess amounts over demand using the same lower of cost or market approach that has been used to value the inventory. The Company also periodically evaluates inventory quantities in consideration of actual loss experience. As a result of these evaluations, the Company recognized total write downs of $0.4 million and $0.9 million for the three months ended September 30, 2015 and 2014 , respectively, and $0.7 million and $1.4 million for the nine months ended September 30, 2015 and 2014 , respectively. Property and Equipment, net Property and equipment are stated at cost less accumulated depreciation. Depreciation is computed using the straight-line method over five years, which is the estimated useful lives of the assets. Leasehold improvements are amortized using the straight-line method over the shorter of the lease term or estimated useful life. Upon retirement or sale, the cost and the related accumulated depreciation are removed from the condensed consolidated balance sheet and the resulting gain or loss is reflected in operations. Maintenance and repairs are charged to operations as incurred. Impairment of Long-Lived Assets The Company reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. When such an event occurs, management determines whether there has been impairment by comparing the anticipated undiscounted future net cash flows to the related asset group’s carrying value. If an asset is considered impaired, the asset is written down to fair value, which is determined based either on discounted cash flows or appraised value, depending on the nature of the asset. There was no impairment of long-lived assets during the three or nine months ended September 30, 2015 and 2014 . Convertible Preferred Stock The Company, prior to the closing of its initial public offering (“IPO”) on September 23, 2015, classified its outstanding convertible preferred stock as temporary equity in the condensed consolidated balance sheet due to the existence of certain change in control events that were not solely within the Company’s control, including liquidation, sale or transfer of the Company, that could trigger the ability of the holders of the convertible preferred stock to call for redemption of shares. Upon the closing of the IPO, all outstanding shares of convertible preferred stock automatically converted into shares of common stock on a one -for-one basis. Revenue Recognition Revenue is comprised of product revenue net of returns, discounts, administration fees and sales rebates. The Company recognizes revenue when persuasive evidence of an arrangement exists, delivery has occurred, the sales price is fixed or determinable and collectability is reasonably assured. Evidence of an arrangement consists of customer orders and the Company typically considers delivery to have occurred once title and risk of loss has been transferred and the product has been delivered to the customer. The Company typically recognizes revenue when products are delivered to hospital customers or distributors. However, with respect to products that the Company consigns to hospitals, which primarily consist of coils, the Company recognizes revenue at the time hospitals utilize products in a procedure. Deferred revenue represents amounts that the Company has already invoiced its customers and are ultimately expected to be recognized as revenue, but for which not all revenue recognition criteria have been met. The Company had a deferred revenue balance of $0.8 million and $1.6 million , as of September 30, 2015 and December 31, 2014 , respectively. The Company’s terms and conditions permit product returns and exchanges, and it records returns reserves in the period when revenue is recognized. Estimates are based on actual historical returns over the prior three years and are recorded as reductions in revenue at the time of sale. Upon recognition, the Company reduces revenue and cost of revenue for the estimated return. Return rates can fluctuate over time, but are sufficiently predictable to allow the Company to estimate expected future product returns. Cost of Revenue Cost of revenue includes direct and indirect costs associated with the manufacture of the Company’s products. Direct costs include material and labor, while indirect costs include inbound freight charges, receiving costs, inspection and testing costs, warehousing costs, royalty expense and other labor and overhead costs incurred in the manufacturing of products. Cost of revenue also includes stock-based compensation, warranty replacement costs, cost of revenue related to product return reserves and excess and obsolete inventory write-downs. Shipping Costs Shipping and handling costs charged to customers are recorded as revenue. Shipping and handling costs are included in cost of revenue. Research and Development (R&D) Expenses R&D costs primarily consist of product development, clinical and regulatory expenses, materials, depreciation and other costs associated with the development of the Company’s products. R&D costs also include related personnel and consultants’ salaries, benefits and related costs, including stock-based compensation. The Company expenses R&D costs as they are incurred. The Company’s clinical trial accruals are based on estimates of patient enrollment and related costs at clinical investigator sites. The Company estimates preclinical and clinical trial expenses based on the services performed pursuant to contracts with research institutions and clinical research organizations that conduct and manage preclinical studies and clinical trials on its behalf. In accruing service fees, the Company estimates the time period over which services will be performed and the level of patient enrollment and activity expended in each period. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual accordingly. Payments made to third parties under these arrangements in advance of the receipt of the related services are recorded as prepaid expenses until the services are rendered. Advertising Costs Advertising costs are included in selling, general and administrative expenses and are expensed as incurred. Advertising costs consist primarily of trade show and booth costs, product demonstration, and marketing materials. Advertising costs were $0.1 million and $0.1 million for the three months ended September 30, 2015 and 2014 , respectively, and were $0.4 million and $0.2 million for the nine months ended September 30, 2015 and 2014, respectively. Stock-Based Compensation The Company recognizes the cost of stock-based compensation in the financial statements based upon fair value. The fair value of restricted stock awards is determined based on the number of units granted and the closing price of the Company’s common stock as of the grant date. The fair value of stock options is determined as of the grant date using the Black-Scholes option pricing model. The Company’s determination of the fair value of stock options is impacted by its common stock price as well as changes in assumptions regarding a number of highly complex and subjective variables. These variables include, but are not limited to, expected term that options will remain outstanding, expected common stock price volatility over the term of the option awards, risk-free interest rates and expected dividends. The fair value is recognized over the period during which an optionee is required to provide services in exchange for the option award, known as the requisite service period (usually the vesting period) on a straight-line basis. Stock-based compensation expense recognized at fair value includes the impact of estimated forfeitures. The Company estimates future forfeitures at the date of grant and revises the estimates, if necessary, in subsequent periods if actual forfeitures differ from those estimates. To the extent actual forfeiture results differ from the estimates, the difference is recorded as a cumulative adjustment in the period forfeiture estimates are revised. No compensation cost is recorded for options that do not vest. Equity instruments issued to non-employees are recorded at their fair value on the measurement date and are subject to periodic adjustments as the underlying equity instruments vest. The fair value of these equity instruments are expensed over the service period. Estimating the fair value of equity-settled awards as of the grant date using valuation models, such as the Black-Scholes option pricing model, is affected by assumptions regarding a number of complex variables. Changes in the assumptions can materially affect the fair value and ultimately how much stock-based compensation expense is recognized. These inputs are subjective and generally require significant analysis and judgment to develop. For all stock options granted to date, the Company estimated the volatility data based on a study of publicly traded industry peer companies. For purposes of identifying these peer companies, the Company considered the industry, stage of development, size and financial leverage of potential comparable companies. The risk-free interest rate is based on the yield available on U.S. Treasury zero-coupon issues similar in duration to the expected term of the equity-settled award. The Company uses the Staff Accounting Bulletin, or SAB, 110, simplified method to calculate the expected term, which is the average of the contractual term and vesting period. Income Taxes The Company accounts for income taxes using the asset and liability method, whereby deferred tax asset and liability account balances are determined based on differences between the 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. The Company provides a valuation allowance to reduce the net deferred tax assets to their estimated realizable value. The calculation of the Company’s current provision for income taxes involves the use of estimates, assumptions and judgments while taking into account current tax laws, interpretation of current tax laws and possible outcomes of future tax audits. The Company has established reserves to address potential exposures related to tax positions that could be challenged by tax authorities. Although the Company believes its estimates, assumptions and judgments to be reasonable, any changes in tax law or its interpretation of tax laws and the resolutions of potential tax audits could significantly impact the amounts provided for income taxes in the Company’s consolidated financial statements. During interim periods, the Company generally utilizes the estimated annual effective tax rate method which involves the use of forecasted information. The discrete method of calculating the estimated effective tax rate, on the other hand, involves the use of actual year-to-date information. For interim periods where the discrete method of calculating the estimated effective tax rate is determined to be a more reliable method than the estimated annual effective tax rate method, the Company will use the more reliable method to estimate its interim period income tax accrual. The calculation of the Company’s deferred tax asset balance involves the use of estimates, assumptions and judgments while taking into account estimates of the amounts and type of future taxable income. Actual future operating results and the underlying amount and type of income could differ materially from the Company’s estimates, assumptions and judgments thereby impacting the Company’s financial position and results of operations. The Company follows the guidance relating to accounting for uncertainty in income taxes, which prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of uncertain tax positions taken or expected to be taken in the Company’s income tax return, and also provides guidance on derecognition, classification, interest and penalties, accounting in interim periods, disclosure and transition. The Company includes interest and penalties related to unrecognized tax benefits within income tax expense in the accompanying consolidated statements of operations. The Company has not incurred any interest or penalties related to unrecognized tax benefits in any of the periods presented. Comprehensive Income The Company is required to display comprehensive income and its components as part of the Company’s consolidated financial statements. Comprehensive income consists of net income, unrealized gains on available-for-sale investments and the effects of foreign currency translation. Deferred Offering Costs Deferred offering costs, which primarily consisted of direct incremental legal and accounting fees were capitalized prior to the closing of the IPO. Upon closing of the IPO, the deferred offering costs were offset against IPO proceeds. Net Income (Loss) Per Share of Common Stock The Company, for the periods prior to the closing of the IPO, calculated its basic and diluted net income (loss) per share attributable to common stockholders in conformity with the two-class method required for companies with participating securities. Under the two-class method, the Company determined whether it had net income (loss) attributable to common stockholders, which included the results of operations less current period preferred stock non-cumulative dividends. If it was determined that the Company did have net income (loss) attributable to common stockholders during a period, the related undistributed earnings were then allocated between common stock and the preferred stock based on the weighted average number of shares outstanding during the period to determine the numerator for the basic net income (loss) per share attributable to common stockholders. In computing diluted net income attributable to common stockholders, undistributed earnings were re-allocated to reflect the potential impact of dilutive securities to determine the numerator for the diluted net income per share attributable to common stockholders. The Company’s basic net income (loss) per share attributable to common stockholders is calculated by dividing the net income (loss) by the weighted average number of shares of common stock outstanding for the period. The diluted net income per share attributable to common stockholders is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period. For purposes of this calculation, options to purchase common stock, restricted stock and common stock warrants are considered common stock equivalents. Recently Issued Accounting Standards In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers , which outlines a comprehensive new revenue recognition model designed to depict the transfer of promised 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. The Company is currently evaluating the impact of this accounting standard. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers — Deferral of the Effective Date to defer the effective date by one year for annual reporting periods beginning after December 15, 2017, including interim reporting periods within that reporting period. Earlier adoption is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. In July 2015, the FASB issued ASU No. 2015-11, Simplifying the Measurement of Inventory , which requires an entity to measure most inventory at the lower of cost and net realizable value, thereby simplifying the current guidance under which an entity must measure inventory at the lower of cost or market. The accounting standard is effective prospectively for annual periods beginning after December 15, 2016, and interim periods therein. Early adoption is permitted as of the beginning of an interim or annual reporting period. The Company is currently evaluating the impact of this accounting standard

Initial Public Offering (IPO)

Initial Public Offering (IPO)	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Initial Public Offering, Common Stock, Warrants, and Common and Preferred Stock Repurchase	Initial Public Offering (IPO) The Company closed its IPO on September 23, 2015, in which it sold 4.6 million shares of common stock at an offering price of $30.00 per share and raised $124.8 million in net proceeds after deducting underwriting discounts and commissions of $9.7 million and other offering expenses of $3.6 million . Upon the closing of the IPO, all outstanding shares of convertible preferred stock were automatically converted into 19,510,410 shares of common stock on a one -for-one basis. Common Stock Each share of common stock is entitled to one vote. The holders of common stock are also entitled to receive dividends whenever funds are legally available and when declared by the board of directors, subject to the prior rights of holders of all classes of stock outstanding. Warrants In connection with the sale of Series B preferred stock in 2004, the Company issued warrants to purchase 211,138 shares of common stock at a purchase price of $0.01 per share. The warrants were exercisable upon grant and had a term of 10 years from the date of grant, which expired on December 31, 2014 . The value of the warrants was calculated using Black-Scholes option pricing model and was deemed to be immaterial. No warrants were outstanding as of September 30, 2015 or December 31, 2014 . Common and Preferred Stock Repurchase The Company’s board of directors approved the repurchase of 70,612 shares of common stock, 45,000 stock options and 45,611 of preferred stock from shareholders in May 2014 for $13.20 per share for a total purchase price of $2.0 million . For the repurchased shares of common stock and stock options, the Company charged the difference between the purchase and market prices of $0.5 million to expense. For the repurchased preferred shares, the excess between the purchase and the issuance price of $0.5 million was treated as a deemed dividend. In addition, the Company closed a tender offer in July 2014 to repurchase shares of preferred stock from existing shareholders at a purchase price of $13.20 per share. The Company repurchased 584,052 shares of preferred stock for a total purchase price of $7.7 million . The excess between the purchase and the issuance price of $5.8 million was treated as a deemed dividend. The repurchased shares of common and preferred stock were retired and remained as authorized but unissued.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the reporting date. The accounting guidance establishes a three-tiered hierarchy, which prioritizes the inputs used in the valuation methodologies in measuring fair value: Level 1 - Quoted prices in active markets for identical assets or liabilities. Level 2 - Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The categorization of a financial instrument within the valuation hierarchy is based on the lowest level of input that is significant to the fair value measurement. The Company classifies its cash equivalents and marketable investments within Level 1 and Level 2, as it uses quoted market prices or alternative pricing sources and models utilizing market observable inputs. The Company determined the fair value of its Level 1 financial instruments, which are traded in active markets, using quoted market prices for identical instruments. Marketable investments classified within Level 2 of the fair value hierarchy are valued based on other observable inputs, including broker or dealer quotations or alternative pricing sources. When quoted prices in active markets for identical assets or liabilities are not available, the Company relies on non-binding quotes from its investment managers, which are based on proprietary valuation models of independent pricing services. These models generally use inputs such as observable market data, quoted market prices for similar instruments, historical pricing trends of a security as relative to its peers and internal assumptions of the independent pricing services. To validate the fair value determination provided by its investment managers, the Company reviews the pricing movement in the context of overall market trends and trading information from its investment managers. In addition, the Company assesses the inputs and methods used in determining the fair value in order to determine the classification of securities in the fair value hierarchy. The Company did not own any Level 3 financial assets or liabilities as of September 30, 2015 or December 31, 2014 . During the three and nine months ended September 30, 2015 and 2014 , the Company did not record impairment charges related to its marketable investments. The Company did not have any financial assets and liabilities measured at fair value on a recurring or non-recurring basis as of September 30, 2015. The following table sets forth the Company’s financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2014 by level within the fair value hierarchy (in thousands): As of December 31, 2014 Level 1 Level 2 Level 3 Fair Value Financial Assets Cash equivalents: Money market funds $ 155 $ — $ — $ 155 Marketable investments: U.S. Agency securities — 6,006 — 6,006 U.S. Treasury 4,009 — — 4,009 Corporate bonds — 29,619 — 29,619 Mutual funds 8,619 — — 8,619 Total $ 12,783 $ 35,625 $ — $ 48,408 The Company did not have any financial assets and liabilities measured at fair value on a non-recurring basis as of December 31, 2014 . During the three and nine months ended September 30, 2015 and 2014 , the Company did not have any transfers of financial assets measured at fair value on a recurring basis to or from Level 1, Level 2 or Level 3. The Company did not hold any Level 3 assets or liabilities as of September 30, 2015 or December 31, 2014 .

Balance Sheet Components

Balance Sheet Components	9 Months Ended
	Sep. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Components	Balance Sheet Components Accounts Receivable, Net The Company’s allowance for doubtful accounts comprised of the following (in thousands): Balance At Beginning Of Period Charged To Costs And Expenses Deductions Balance At End Of Period Allowance for Doubtful Accounts For the year ended December 31, 2014 $ 471 $ 150 $ (19 ) $ 602 For the nine months ended September 30, 2015 602 (108 ) — 494 Prepaid Expenses and Other Current Assets The Company’s prepaid expenses and other current assets comprised of the following (in thousands): September 30, December 31, Prepaid expenses $ 5,772 $ 3,130 Income tax receivable 318 1,654 Other current assets 177 331 Prepaid expenses and other current assets $ 6,267 $ 5,115 Marketable Investments The Company did not have any marketable investments as of September 30, 2015 . The Company’s marketable investments as of December 31, 2014 were as follows (in thousands): Marketable Investments Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Agency securities $ 6,012 $ 3 $ (9 ) $ 6,006 U.S. Treasury 4,011 — (2 ) $ 4,009 Corporate bonds 29,834 4 (219 ) $ 29,619 Mutual funds 8,768 — (149 ) $ 8,619 Total $ 48,625 $ 7 $ (379 ) $ 48,253 During the nine months ended September 30, 2015 , the Company sold all of its marketable investments and recorded a realized loss of $0.5 million . For the nine months ended September 30, 2014 , gains or losses realized on the sale of investments were insignificant. As of December 31, 2014 , there were no securities that had been in a loss position for more than twelve months. The contractual maturities of the Company’s marketable investments as of December 31, 2014 were as follows (in thousands): December 31, 2014 Fair Value Due in one year $ 16,442 Due in one to five years 31,811 Total $ 48,253 Inventories The components of inventories consisted of the following (in thousands): September 30, December 31, Raw materials $ 9,477 $ 5,105 Work in process 1,244 543 Finished goods 39,603 27,803 Inventories $ 50,324 $ 33,451 Property and Equipment, Net Property and equipment, net consisted of the following (in thousands): September 30, December 31, Machinery and equipment $ 8,166 $ 5,089 Furniture and fixtures 2,004 519 Leasehold improvements 1,434 379 Software 744 599 Computers 565 153 Construction in progress 341 1,931 Total property and equipment 13,254 8,670 Less: Accumulated depreciation and amortization (4,608 ) (3,489 ) Property and equipment, net $ 8,646 $ 5,181 Depreciation and amortization expense was $0.5 million and $0.2 million for the three months ended September 30, 2015 and 2014 , respectively, and was $1.2 million and $0.5 million for the nine months ended September 30, 2015 and 2014 , respectively. Accrued Liabilities The following table shows the components of accrued liabilities (in thousands): September 30, December 31, Payroll and employee-related expenses $ 12,850 $ 8,221 Sales return reserve 2,839 2,164 Preclinical and clinical trial cost 1,405 2,319 Deferred revenue 784 1,591 Product warranty 618 314 Sales tax payable 412 306 Income tax payable 54 332 Other accrued liabilities 5,291 3,228 Total accrued liabilities $ 24,253 $ 18,475 The estimated product warranty accrual was as follows (in thousands): September 30, December 31, Balance at the beginning of the period $ 314 $ 323 Accruals of warranties issued 545 149 Settlements of warranty claims (241 ) (158 ) Balance at the end of the period $ 618 $ 314

Credit Facility

Credit Facility	9 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
Credit Facility	Credit Facility In May 2012, the Company entered into a revolving credit facility of $15.0 million with Wells Fargo Bank, National Association. The credit facility was collateralized by the Company’s investment balances. The interest on the credit facility was based on the daily one-month London Inter-Bank Offered Rate, plus 1.75% and was payable monthly. Any outstanding balance on the credit facility was due in full on June 1, 2015. The credit facility contained customary covenants for credit facilities of this type, including limitations on disposition of assets and changes in control. In May 2014, in conjunction with its Series F preferred stock financing, the Company paid the then outstanding balance on the credit facility and terminated the credit facility.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2015
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Notes Receivable from Stockholders In March 2005, options to purchase 250,000 shares of common stock, subject to repurchase by the Company, were exercised in exchange for a full recourse promissory note totaling $21,250 . The note bears interest at 2.92% per year, compounded annually. In July 2011, options to purchase 5,000 shares of common stock were exercised in exchange for a full recourse promissory note totaling $4,600 . The note is noninterest bearing and is due in full on December 31, 2016. As of September 30, 2015 and December 31, 2014 , outstanding promissory notes were $25,850 and $0.1 million , respectively.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Lease Commitments The Company leases its offices and other equipment under non-cancelable operating leases that expire at various dates in 2029. Rent expense for the three months ended September 30, 2015 and 2014 was $0.9 million and $0.4 million , respectively, and was $2.3 million and $1.3 million , for the nine months ended September 30, 2015 and 2014 , respectively. Future minimum lease payments under the non-cancelable operating leases as of September 30, 2015 are as follows (in thousands): Lease Payments Three Months Ending December 31, 2015 $ 766 Year Ending December 31: 2016 3,149 2017 3,145 2018 3,141 2019 3,223 2020 3,299 Thereafter 32,486 Total future minimum lease payments $ 49,209 Purchase Commitments The Company had non-cancellable purchase obligations to suppliers for the nine months ended September 30, 2015 of $11.7 million . Royalty Obligations In March 2005, the Company entered into a license agreement that requires the Company to make minimum royalty payments to the licensor, on a quarterly basis. As of September 30, 2015 and December 31, 2014 , the license agreement requires minimum annual royalty payments of $0.1 million and $0.1 million in equal quarterly installments, respectively. On each January 1, the quarterly calendar year minimum royalty shall be adjusted to equal the prior year’s minimum royalty adjusted by a percentage equal to the percentage change in the “consumer price index for all urban consumers” for the prior calendar year as reported by the U.S. Department of Labor. Unless terminated earlier, the term of the license agreement shall continue until the expiration of the last to expire patent that covers that licensed product or for the period of 15 years following the first commercial sale of such licensed product, whichever is longer. The first commercial sale occurred in June 2007. In April 2012, the Company entered into an agreement that requires the Company to pay a 5% royalty on sales of products covered under applicable patents, on a quarterly basis. The first commercial sale occurred in April 2014. Unless terminated earlier, the royalty term for each applicable product shall continue for fifteen years following the first commercial sale of such patented product, or when the applicable patent covering such product has expired, whichever is sooner. In April 2015, the Company entered into a royalty agreement that requires the Company to pay a 2% royalty on sales of certain products covered by the agreement, on a quarterly basis. The Company began the first commercial sale of the covered products in July 2015. Unless terminated earlier, the royalty term for each covered product shall continue for twenty years following the first commercial sale of the covered products. Royalty expense included in cost of sales for the three months ended September 30, 2015 and 2014 was $0.6 million and $0.3 million , respectively, and was $1.4 million and $0.8 million for the nine months ended September 30, 2015 and 2014 , respectively. Contingencies From time to time, the Company may have certain contingent liabilities that arise in the ordinary course of business. The Company accrues a liability for such matters when it is probable that future expenditures will be made and such expenditures can be reasonably estimated. There have been no contingent liabilities requiring accrual or disclosure at September 30, 2015 or December 31, 2014 . Indemnification The Company enters into standard indemnification arrangements in the ordinary course of business. Pursuant to these arrangements, the Company indemnifies, holds harmless, and agrees to reimburse the indemnified parties for losses suffered or incurred by the indemnified party, in connection with any trade secret, copyright, patent or other intellectual property infringement claim by any third-party with respect to the Company’s technology. The term of these indemnification agreements is generally perpetual. The maximum potential amount of future payments the Company could be required to make under these agreements is not determinable because it involves claims that may be made against the Company in the future, but have not yet been made. The Company has entered into indemnification agreements with its directors and officers that may require the Company to indemnify its directors and officers against liabilities that may arise by reason of their status or service as directors or officers, other than liabilities arising from willful misconduct of the individual. The Company has not incurred costs to defend lawsuits or settle claims related to these indemnification agreements. No liability associated with such indemnifications has been recorded to date. Litigation The Company was made aware of potential product liability claimants who allegedly suffered injuries as a result of aneurysm procedures performed in the United States and the United Kingdom in which the Penumbra Coil 400 was used. The Company has not been served with formal complaints; however, the attorney for the purported U.S. claimant has indicated that a civil suit will be brought against the Company shortly. While specific damages have not been asserted, counsel for the purported claimant indicated that he expects that a jury could award $35 million in damages were this matter to go to trial. This amount is substantially in excess of the Company’s insurance coverage. The attorney for the potential claimant in the United Kingdom has not specified any damage amount. As no litigation has been instituted in either of these cases, and therefore neither the Company nor the potential claimants have engaged in discovery, the Company is unable to assess the merits of the claims. The Company expects to vigorously defend any litigation that might be brought, as the Company believes there would be substantial questions regarding causation, liability and damages. From time to time, the Company is subject to claims and assessments in the ordinary course of business. The Company is not currently a party to any litigation matter that, individually or in the aggregate, is expected to have a material adverse effect on the Company’s business, financial condition, results of operations or cash flows.

Convertible Preferred Stock

Convertible Preferred Stock	9 Months Ended
	Sep. 30, 2015
Temporary Equity Disclosure [Abstract]
Convertible Preferred Stock	Convertible Preferred Stock The convertible preferred stock at December 31, 2014 consisted of the following (in thousands, except shares): Series Shares Authorized Shares Issued and Outstanding Proceeds, Net of Issuance Costs Aggregate Liquidation Amount Series A Preferred Stock 1,000,000 1,000,000 $ 299 $ 554 Series B Preferred Stock 4,287,486 4,005,338 6,536 11,725 Series C Preferred Stock 4,388,715 4,168,218 13,266 22,238 Series D Preferred Stock 3,944,733 3,881,459 19,647 30,976 Series E Preferred Stock 1,973,684 1,909,940 14,507 21,609 Series F Preferred Stock 5,303,031 4,545,455 57,212 62,259 Undesignated 4,102,351 — — — Total preferred stock 25,000,000 19,510,410 $ 111,467 $ 149,361 Upon the closing of the IPO on September 23, 2015, all outstanding shares of convertible preferred stock were automatically converted into 19,510,410 shares of common stock on a one -for-one basis and the related balance was reclassified from temporary equity to common stock and additional paid-in capital.

Common Stock

Common Stock	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Initial Public Offering, Common Stock, Warrants, and Common and Preferred Stock Repurchase	Initial Public Offering (IPO) The Company closed its IPO on September 23, 2015, in which it sold 4.6 million shares of common stock at an offering price of $30.00 per share and raised $124.8 million in net proceeds after deducting underwriting discounts and commissions of $9.7 million and other offering expenses of $3.6 million . Upon the closing of the IPO, all outstanding shares of convertible preferred stock were automatically converted into 19,510,410 shares of common stock on a one -for-one basis. Common Stock Each share of common stock is entitled to one vote. The holders of common stock are also entitled to receive dividends whenever funds are legally available and when declared by the board of directors, subject to the prior rights of holders of all classes of stock outstanding. Warrants In connection with the sale of Series B preferred stock in 2004, the Company issued warrants to purchase 211,138 shares of common stock at a purchase price of $0.01 per share. The warrants were exercisable upon grant and had a term of 10 years from the date of grant, which expired on December 31, 2014 . The value of the warrants was calculated using Black-Scholes option pricing model and was deemed to be immaterial. No warrants were outstanding as of September 30, 2015 or December 31, 2014 . Common and Preferred Stock Repurchase The Company’s board of directors approved the repurchase of 70,612 shares of common stock, 45,000 stock options and 45,611 of preferred stock from shareholders in May 2014 for $13.20 per share for a total purchase price of $2.0 million . For the repurchased shares of common stock and stock options, the Company charged the difference between the purchase and market prices of $0.5 million to expense. For the repurchased preferred shares, the excess between the purchase and the issuance price of $0.5 million was treated as a deemed dividend. In addition, the Company closed a tender offer in July 2014 to repurchase shares of preferred stock from existing shareholders at a purchase price of $13.20 per share. The Company repurchased 584,052 shares of preferred stock for a total purchase price of $7.7 million . The excess between the purchase and the issuance price of $5.8 million was treated as a deemed dividend. The repurchased shares of common and preferred stock were retired and remained as authorized but unissued.

Warrants

Warrants	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Initial Public Offering, Common Stock, Warrants, and Common and Preferred Stock Repurchase	Initial Public Offering (IPO) The Company closed its IPO on September 23, 2015, in which it sold 4.6 million shares of common stock at an offering price of $30.00 per share and raised $124.8 million in net proceeds after deducting underwriting discounts and commissions of $9.7 million and other offering expenses of $3.6 million . Upon the closing of the IPO, all outstanding shares of convertible preferred stock were automatically converted into 19,510,410 shares of common stock on a one -for-one basis. Common Stock Each share of common stock is entitled to one vote. The holders of common stock are also entitled to receive dividends whenever funds are legally available and when declared by the board of directors, subject to the prior rights of holders of all classes of stock outstanding. Warrants In connection with the sale of Series B preferred stock in 2004, the Company issued warrants to purchase 211,138 shares of common stock at a purchase price of $0.01 per share. The warrants were exercisable upon grant and had a term of 10 years from the date of grant, which expired on December 31, 2014 . The value of the warrants was calculated using Black-Scholes option pricing model and was deemed to be immaterial. No warrants were outstanding as of September 30, 2015 or December 31, 2014 . Common and Preferred Stock Repurchase The Company’s board of directors approved the repurchase of 70,612 shares of common stock, 45,000 stock options and 45,611 of preferred stock from shareholders in May 2014 for $13.20 per share for a total purchase price of $2.0 million . For the repurchased shares of common stock and stock options, the Company charged the difference between the purchase and market prices of $0.5 million to expense. For the repurchased preferred shares, the excess between the purchase and the issuance price of $0.5 million was treated as a deemed dividend. In addition, the Company closed a tender offer in July 2014 to repurchase shares of preferred stock from existing shareholders at a purchase price of $13.20 per share. The Company repurchased 584,052 shares of preferred stock for a total purchase price of $7.7 million . The excess between the purchase and the issuance price of $5.8 million was treated as a deemed dividend. The repurchased shares of common and preferred stock were retired and remained as authorized but unissued.

Stock Option Plans

Stock Option Plans	9 Months Ended
	Sep. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Option Plans	Stock Option Plans 2005 Stock Plan The Company adopted its 2005 Stock Plan (the 2005 Plan) in January 2005. The 2005 Plan was subsequently amended and restated in 2006, 2007, 2008 and 2010. As of September 30, 2015 and December 31, 2014 , the Company had granted options to purchase 5,431,017 and 5,431,017 shares of common stock, respectively, under the 2005 Plan, of which options to purchase 1,767,324 and 2,707,176 shares of common stock were outstanding, and options to purchase 15,662 and 33,081 shares of common stock had been early exercised and were unvested and subject to repurchase, as of September 30, 2015 and December 31, 2014 , respectively. Under the 2005 Plan, the board of directors could grant incentive stock options (ISO), nonqualified stock options (NSO), or stock awards to eligible persons, including employees, nonemployees, directors, consultants and other independent advisors who provide services to the Company. Stock purchase rights could also be granted under the Plan. The board of directors had the authority to determine to whom options would be granted, the number of options, the term and the exercise price. ISOs could only be granted to Company employees, which include officers and directors of the Company. NSOs and stock purchase rights could be granted to employees and consultants. For individuals holding more than 10% of the voting rights of all classes of stock, the exercise price for an ISO could not be less than 110% of fair market value. Options are exercisable immediately upon the optionee entering into a restricted stock purchase agreement with respect to any unvested options. Options generally vest annually at a rate of 1/4 after the first year and 1/48 per month thereafter. The term of the options is no longer than five years for ISOs, for which the grantee owns greater than 10% of the voting power of all classes of stock and no longer than 10 years for all other options. 2011 Equity Incentive Plan The Company adopted its 2011 Equity Incentive Plan (the 2011 Plan) in October 2011. As of September 30, 2015 and December 31, 2014 , the Company had granted options to purchase 145,000 and 145,000 shares of common stock, respectively, under the 2011 Plan, of which options to purchase 145,000 and 145,000 shares of common stock were outstanding at September 30, 2015 and December 31, 2014, respectively. The Company had also granted 505,000 and 505,000 shares of restricted stock under the 2011 Plan, of which 249,125 and 367,126 shares were unvested and subject to forfeiture and 4,667 and 1,667 shares had been forfeited as of September 30, 2015 and December 31, 2014 , respectively. Under the 2011 Plan, the board of directors could grant ISOs, NSOs, restricted stock, or restricted stock units (RSU) to eligible persons, including employees, directors and consultants who provide services to the Company. Stock Appreciation Rights (SAR) could also be granted under the 2011 Plan. The board of directors had the authority to determine to whom options would be granted, the number of options, the term and the exercise price. ISOs could only be granted to Company employees, which include officers and directors of the Company. NSOs, SARs, restricted stock and RSUs could be granted to employees and consultants. For individuals holding more than 10% of the voting rights of all classes of stock, the exercise price for an ISO could not be less than 110% of fair market value. Stock options granted under the 2011 Plan generally have a contractual life of ten years, and generally vest over a period of four years. Amended and Restated 2014 Equity Incentive Plan The Company adopted its 2014 Equity Incentive Plan in May, 2014. This plan was amended and restated as of the business day immediately prior to the date of the Prospectus (as amended and restated, the 2014 Plan). The 2014 Plan replaced the 2011 Plan and the 2005 Plan. No further equity awards may be granted under the 2011 Plan or the 2005 Plan. As of September 30, 2015 and December 31, 2014 , the Company had granted options to purchase 1,857,900 and 48,500 shares of common stock under the 2014 Plan, 1,853,770 and 48,500 of which were outstanding and 4,130 and 1,000 options had been forfeited as of September 30, 2015 and December 31, 2014 , respectively. The Company had also granted 673,361 and 0 shares of restricted stock under the 2014 Plan, as of September 30, 2015 and December 31, 2014 , respectively, of which 510,146 and 0 shares were unvested and subject to forfeiture as of such dates. Employee Stock Purchase Plan The Employee Stock Purchase Plan ESPP became effective on September 17, 2015. Under the ESPP, 600,000 shares of common stock are initially reserved for issuance, with the number of shares reserved for issuance automatically increasing each year pursuant to an “evergreen” provision set forth in the ESPP. All employees of the Company and its designated subsidiaries are eligible to participate in the ESPP. Each offering to the Company’s employees to purchase stock under the ESPP will begin on each May 20 and November 20 and will end on the following November 19 and May 19, respectively, each referred to as offering periods, except that the first offering period under the ESPP began on September 17, 2015 and will end on May 19, 2016. Under the ESPP, each employee may purchase shares by authorizing payroll deductions at a minimum of 1% and up to 15% of his or her eligible compensation for each pay period. Unless the participating employee withdraws from the offering, his or her accumulated payroll deductions will be used to purchase the Company’s common stock on the last business day of the offering period at a price equal to 85% of the fair market value of the common stock on either the first or the last day of the offering period, whichever is lower, provided that no more than 2,000 shares of the Company’s common stock or such other lesser maximum number established by the plan administrator may be purchased by any one employee during each offering period. Under applicable tax rules, an employee may purchase no more than $25,000 worth of common stock, valued at the start of the purchase period, under the ESPP in any calendar year. Early Exercises Stock options granted under the 2005 Plan, 2011 Plan and 2014 Plan allow the board of directors to grant awards to provide employee option holders the right to elect to exercise unvested options in exchange for restricted common stock. Unvested shares, which amounted to 15,662 and 33,081 as of September 30, 2015 and December 31, 2014 , respectively, were subject to a repurchase right held by the Company at the original issue price in the event the optionees’ employment was terminated either voluntarily or involuntarily. For exercises of employee options, this right lapses according to the vesting schedule designated on the associated option grant. The repurchase terms are considered to be a forfeiture provision. The shares purchased by the employees pursuant to the early exercise of stock options are not deemed to be issued or outstanding for accounting purposes until those shares vest, though they are legally issued and outstanding. In addition, cash received from employees for exercise of unvested options is treated as a refundable deposit shown as a liability on the consolidated balance sheets. As of September 30, 2015 and December 31, 2014 , cash received related to unvested shares totaled $0.1 million and $0.1 million , respectively. Amounts recorded are transferred into common stock and additional paid-in-capital as the shares vest. The following table summarizes the activity of stock options during the nine months ended September 30, 2015 : Number of Shares Weighted- Average Exercise Price Balance, December 31, 2014 2,900,676 $ 2.66 Options granted 1,809,400 21.47 Options exercised (938,456 ) 0.95 Options cancelled (5,526 ) 11.14 Balance, September 30, 2015 3,766,094 12.11 The weighted average grant date fair value of the employee stock options granted during the nine months ended September 30, 2015 was $9.69 per share. The following table summarizes the activity of unvested restricted stock during the nine months ended September 30, 2015 : Number of Shares Weighted Average Grant Date Fair Value Unvested at December 31, 2014 367,126 $ 7.26 Granted 673,361 14.60 Vested (278,216 ) 11.77 Cancelled/Forfeited (3,000 ) 7.75 Unvested and expected to vest at September 30, 2015 759,271 12.12 As of September 30, 2015 , total unrecognized compensation cost was $25.6 million related to unvested share-based compensation arrangements which is expected to be recognized over a weighted average period of 2.2 years. The following table sets forth the stock-based compensation expense included in the consolidated statements of operations (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Cost of sales $ 141 $ 65 $ 271 $ 189 Research and development 100 23 282 70 Sales, general and administrative 1,269 284 4,573 815 $ 1,510 $ 372 $ 5,126 $ 1,074

Common and Preferred Stock Repu

Common and Preferred Stock Repurchase	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Initial Public Offering, Common Stock, Warrants, and Common and Preferred Stock Repurchase	Initial Public Offering (IPO) The Company closed its IPO on September 23, 2015, in which it sold 4.6 million shares of common stock at an offering price of $30.00 per share and raised $124.8 million in net proceeds after deducting underwriting discounts and commissions of $9.7 million and other offering expenses of $3.6 million . Upon the closing of the IPO, all outstanding shares of convertible preferred stock were automatically converted into 19,510,410 shares of common stock on a one -for-one basis. Common Stock Each share of common stock is entitled to one vote. The holders of common stock are also entitled to receive dividends whenever funds are legally available and when declared by the board of directors, subject to the prior rights of holders of all classes of stock outstanding. Warrants In connection with the sale of Series B preferred stock in 2004, the Company issued warrants to purchase 211,138 shares of common stock at a purchase price of $0.01 per share. The warrants were exercisable upon grant and had a term of 10 years from the date of grant, which expired on December 31, 2014 . The value of the warrants was calculated using Black-Scholes option pricing model and was deemed to be immaterial. No warrants were outstanding as of September 30, 2015 or December 31, 2014 . Common and Preferred Stock Repurchase The Company’s board of directors approved the repurchase of 70,612 shares of common stock, 45,000 stock options and 45,611 of preferred stock from shareholders in May 2014 for $13.20 per share for a total purchase price of $2.0 million . For the repurchased shares of common stock and stock options, the Company charged the difference between the purchase and market prices of $0.5 million to expense. For the repurchased preferred shares, the excess between the purchase and the issuance price of $0.5 million was treated as a deemed dividend. In addition, the Company closed a tender offer in July 2014 to repurchase shares of preferred stock from existing shareholders at a purchase price of $13.20 per share. The Company repurchased 584,052 shares of preferred stock for a total purchase price of $7.7 million . The excess between the purchase and the issuance price of $5.8 million was treated as a deemed dividend. The repurchased shares of common and preferred stock were retired and remained as authorized but unissued.

Employee Benefit Plans

Employee Benefit Plans	9 Months Ended
	Sep. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Employee Benefit Plans	Employee Benefit Plans The Company offers a retirement savings plan under Section 401(k) of the Internal Revenue Code (the IRC) to its eligible U.S. employees whereby they may contribute up to the maximum amount permitted by IRC. Under the plan, the Company in the third quarter of 2015, began 401(k) matching of eligible compensation, subject to a maximum dollar threshold. Contribution expense was not material for the three and nine months ended September 30, 2015 .

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company’s income tax expense (benefit), deferred tax assets and liabilities, and reserves for unrecognized tax benefits reflect management's best assessment of estimated current and future taxes to be paid. The Company is subject to income taxes in both the United States and foreign jurisdictions. Significant judgments and estimates are required in determining the consolidated income tax expense (benefit). The Company’s effective tax rate decreased to 56.8% for the three months ended September 30, 2015 , compared to 56.9% for the three months ended September 30, 2014 . The Company’s effective tax rate increased to 65.9% for the nine months ended September 30, 2015 , compared to 32.8% for the nine months ended September 30, 2014 . The Company historically calculated the provision for income taxes during interim reporting periods by applying an estimate of the annual effective tax rate for the full fiscal year to “ordinary” income or loss (pretax income or loss excluding unusual or infrequently occurring discrete items) for the reporting period. Although management believes the use of the annual effective tax rate method to be appropriate for prior interim reporting periods, for the fiscal three- and nine-month periods ended September 30, 2015 , the Company used a discrete effective tax rate method to calculate taxes. The Company determined that since small changes in estimated “ordinary” income for fiscal 2015 would result in significant changes in the estimated annual effective tax rate, the discrete effective tax method would provide a more reliable estimate for the fiscal three- and nine-month periods ended September 30, 2015 . It is possible that management may determine the use of the discrete effective tax rate method to be more appropriate than the annual effective tax rate method in future interim periods as well.

Net Income (Loss) per Share of

Net Income (Loss) per Share of Common Stock attributable to Common Stockholders	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Net Income (Loss) per Share of Common Stock attributable to Common Stockholders	Net Income (Loss) per Share of Common Stock attributable to Common Stockholders A reconciliation of the numerator and denominator used in the calculation of the basic and diluted net income (loss) per share attributable to common stockholders is as follows (in thousands except share and per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Net income (loss) per share: Numerator Net income $ 901 $ 172 $ 732 $ 1,829 Less: Deemed dividend paid to preferred stockholders upon repurchase — (6,344 ) — (6,344 ) Less: Undistributed income attributable to preferred stockholders (625 ) — (557 ) — Add: Undistributed loss attributable to preferred stockholders — 4,980 — 3,582 Net income (loss) attributable to common stockholders—basic and diluted $ 276 $ (1,192 ) $ 175 $ (933 ) Denominator Weighted average shares used to compute net income (loss) attributable to common stockholders —Basic 7,853,730 4,688,045 5,962,031 4,577,725 Potential dilutive options, as calculated using treasury stock method 1,979,194 — 2,362,685 — Potential dilutive restricted stock, as calculated using treasury stock method 356,324 — 169,935 — Weighted average shares used to compute net income (loss) attributable to common stockholders —Diluted 10,189,248 4,688,045 8,494,651 4,577,725 Net income (loss) per share attributable to common stockholders —Basic $ 0.04 $ (0.25 ) $ 0.03 $ (0.20 ) —Diluted $ 0.03 $ (0.25 ) $ 0.02 $ (0.20 ) The following outstanding shares of potentially dilutive securities were excluded from the computation of diluted net income (loss) per share of common stock for the periods presented, because the effect of including them would have been anti-dilutive: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Options to purchase common stock 1,321,250 2,976,992 1,321,250 2,976,992 Restricted stock 6,500 368,793 6,500 368,793 Common stock warrants — 75,972 — 75,972 Total 1,327,750 3,421,757 1,327,750 3,421,757

Geographic Areas and Product Sa

Geographic Areas and Product Sales	9 Months Ended
	Sep. 30, 2015
Segment Reporting [Abstract]
Geographic Areas and Product Sales	Geographic Areas and Product Sales The Company’s revenue by geographic area, based on the destination to which the Company ships its products, was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 United States $ 35,394 $ 22,305 $ 89,364 $ 59,281 Japan 5,420 3,467 14,030 10,796 Other International 9,602 6,692 28,285 20,030 Total $ 50,416 $ 32,464 $ 131,679 $ 90,107 The following table sets forth revenue by product category (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Neuro $ 36,309 $ 26,988 $ 102,363 $ 77,056 Peripheral Vascular 14,107 5,476 29,316 13,051 Total $ 50,416 $ 32,464 $ 131,679 $ 90,107 The Company does not have significant long-lived assets outside the U.S.

Summary of Significant Accoun25

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Basis of Presentation	The accompanying interim condensed consolidated balance sheet as of September 30, 2015 , the interim condensed consolidated statements of operations for the three and nine months ended September 30, 2015 and 2014 , the interim condensed consolidated statement of preferred stock and stockholders’ equity (deficit) for the nine months ended September 30, 2015 , and the interim condensed consolidated statements of cash flows for the nine months ended September 30, 2015 and 2014 are unaudited. The unaudited interim condensed consolidated financial statements included herein have been prepared by the Company in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and the applicable rules and regulations of the Securities and Exchange Commission (“SEC”) for interim financial information. Accordingly, they do not include all of the information and notes required by U.S. GAAP for complete financial statements. The December 31, 2014 condensed consolidated balance sheet was derived from the audited financial statements as of that date, but does not include all of the information and footnotes required by GAAP for complete financial statements. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements and, in the opinion of management, reflect all adjustments of a normal recurring nature considered necessary to state fairly the Company’s financial position as of September 30, 2015 and results of its operations for the three and nine months ended September 30, 2015 and 2014 , and the cash flows for the nine months ended September 30, 2015 and 2014 . The interim results for the nine months ended September 30, 2015 are not necessarily indicative of the results that may be expected for the year ending December 31, 2015 or for any other future annual or interim period. The information included in this quarterly report on Form 10-Q should be read in conjunction with the financial statements and notes thereto contained in the Company’s Prospectus dated September 17, 2015 as filed by the Company with the SEC pursuant to Rule 424(b)(4) under the Securities Act of 1933, as amended, relating to the Company’s Registration Statement on Form S-1 (“Prospectus”) (File No. 333-206412).
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities and equity accounts; disclosure of contingent assets and liabilities at the date of the financial statements; and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates, including those related to provisions for doubtful accounts, sales return reserve, warranty reserves, valuation of inventories, useful lives of property and equipment, income taxes, the valuation of equity instruments and contingencies, among others. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other data. Actual results could differ from those estimates.
Segments	Segments The Company determined its operating segment on the same basis that it uses to evaluate its performance internally. The Company has one business activity: the design, development, manufacturing and marketing of innovative medical devices, and operates as one operating segment. The Company’s chief operating decision-maker, its Chief Executive Officer, reviews its operating results for the purpose of allocating resources and evaluating financial performance. The Company determines revenue by geographic area, based on the destination to which it ships its products.
Foreign Currency Translation	Foreign Currency Translation The Company’s condensed consolidated financial statements are prepared in United States Dollars (USD). Its foreign subsidiaries use their local currency as their functional currency and maintain their records in the local currency. Accordingly, the assets and liabilities of these subsidiaries are translated into USD using the current exchange rates in effect at the balance sheet date and equity accounts are translated into USD using historical rates. Revenues and expenses are translated using the average exchange rates in effect. The resulting foreign currency translation adjustments are recorded in other comprehensive income in the condensed consolidated balance sheets. Transactions denominated in foreign currency are translated at exchange rates at the date of transaction with foreign currency gains (losses) recorded in other income (expense), net in the condensed consolidated statements of operations and other comprehensive income. The Company recognized net foreign currency transaction gains of $0.1 million and $0.1 million during the three months ended September 30, 2015 and 2014 , respectively, and $11,000 and $0.2 million during the nine months ended September 30, 2015 and 2014 , respectively. As the Company’s international operations grow, its risks associated with fluctuation in currency rates will become greater, and the Company will continue to reassess its approach to managing this risk. In addition, currency fluctuations or a weakening USD can increase the costs of the Company’s international expansion. To date, the Company has not entered into any foreign currency hedging contracts, since exchange rate fluctuations have not had a material impact on its operating results and cash flows.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash and cash equivalents, marketable investments and accounts receivable. The majority of the Company’s cash is held by one financial institution in the United States in excess of federally insured limits. The Company maintained investments in money market funds that were not federally insured during the year ended December 31, 2014 and held cash in foreign banks of approximately $2.3 million and $0.8 million at September 30, 2015 and December 31, 2014 , respectively, that was not federally insured. The Company has not experienced any losses on its deposits of cash and cash equivalents. All of the Company’s revenue has been derived from sales of its products in the United States and international markets. The Company uses both its own salesforce and independent distributors to sell its products. Concentrations of credit risk with respect to accounts receivable are limited due to the large number of entities comprising the Company’s customer base. The Company performs ongoing credit evaluations of its customers, including its distributors, does not require collateral, and maintains allowances for potential credit losses on customer accounts when deemed necessary.
Significant Risks and Uncertainties	Significant Risks and Uncertainties The Company is subject to risks common to medical device companies including, but not limited to, new technological innovations, dependence on key personnel, protection of proprietary technology, compliance with government regulations, product liability, uncertainty of market acceptance of products and the potential need to obtain additional financing. The Company is dependent on third party suppliers, in some cases single-source suppliers. There can be no assurance that the Company’s products will continue to be accepted in the marketplace, nor can there be any assurance that any future products can be developed or manufactured at an acceptable cost and with appropriate performance characteristics, or that such products will be successfully marketed, if at all. The Company’s products require approval or clearance from the U.S. Food and Drug Administration prior to commencing commercial sales in the United States. There can be no assurance that the Company’s products will receive all of the required approvals or clearances. Approvals or clearances are also required in foreign jurisdictions in which the Company sells its products. If the Company is denied such approvals or clearances or such approvals or clearances are delayed, it may have a material adverse impact on the Company’s results of operations, financial position and liquidity.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Carrying amounts of certain of the Company’s financial instruments, including cash equivalents, accounts receivable, prepaid expenses and other current assets, accounts payable and accrued liabilities, approximate fair value due to their relatively short maturities.
Cash and Cash Equivalents	The Company invests its cash primarily in money market funds and in highly liquid debt instruments of U.S. federal and municipal governments and their agencies and corporate debt securities. All highly liquid investments with stated maturities of three months or less from the date of purchase are classified as cash equivalents; all highly liquid investments with stated maturities of greater than three months are classified as marketable investments. The majority of the Company’s cash and investments are held in U.S. banks.
Marketable Investments	The Company determines the appropriate classification of its investments in marketable investments at the time of purchase and re-evaluates such designation at each balance sheet date. The Company’s marketable investments have been classified and accounted for as available-for-sale. Investments with remaining maturities of more than one year are viewed by the Company as available to support current operations and are classified as current assets under the caption marketable investments in the accompanying condensed consolidated balance sheets. Investments in marketable investments are carried at fair value, with the unrealized gains and losses reported as a component of accumulated other comprehensive loss. Any realized gains or losses on the sale of marketable investments are determined on a specific identification method, and such gains and losses are reflected as a component of other income (expense), net. Impairment of Marketable Investments After determining the fair value of available-for-sale debt instruments, gains or losses on these securities are recorded to accumulated other comprehensive income (loss) until either the security is sold or the Company determines that the decline in value is other-than-temporary. The primary differentiating factors that the Company considers in classifying impairments as either temporary or other-than-temporary impairments is the intent and ability to retain the 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.
Accounts Receivable	Accounts Receivable Accounts receivable are stated at invoice value less estimated allowances for doubtful accounts. The Company continually monitors customer payments and maintains a reserve for estimated losses resulting from its customers’ inability to make required payments. The Company considers factors such as historical experience, credit quality, age of the accounts receivable balances, geographic related risks and economic conditions that may affect a customer’s ability to pay. In cases where there are circumstances that may impair a specific customer’s ability to meet its financial obligations, a specific allowance is recorded against amounts due, and thereby reduces the net recognized receivable to the amount reasonably believed to be collectible.
Inventories	Inventories Inventories are stated at the lower of cost (determined under the first-in first-out method) or market. Write downs are provided for raw materials, components or finished goods that are determined to be excessive or obsolete. Market value is determined as the lower of replacement cost or net realizable value. The Company regularly reviews inventory quantities in consideration of actual loss experience, projected future demand and remaining shelf life to record a provision for excess and obsolete inventory when appropriate. The estimate of excess quantities is subjective and primarily dependent on the Company’s estimates of future demand for a particular product or components or raw materials used in the manufacturing of such product. If the estimate of future demand is inaccurate based on actual sales, the Company may increase the write down for excess inventory and record a charge to inventory impairment in the accompanying condensed consolidated statements of operations and comprehensive income. The Company periodically evaluates the carrying value of inventory on hand for potential excess amounts over demand using the same lower of cost or market approach that has been used to value the inventory. The Company also periodically evaluates inventory quantities in consideration of actual loss experience.
Property and Equipment, Net	Property and Equipment, net Property and equipment are stated at cost less accumulated depreciation. Depreciation is computed using the straight-line method over five years, which is the estimated useful lives of the assets. Leasehold improvements are amortized using the straight-line method over the shorter of the lease term or estimated useful life. Upon retirement or sale, the cost and the related accumulated depreciation are removed from the condensed consolidated balance sheet and the resulting gain or loss is reflected in operations. Maintenance and repairs are charged to operations as incurred.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. When such an event occurs, management determines whether there has been impairment by comparing the anticipated undiscounted future net cash flows to the related asset group’s carrying value. If an asset is considered impaired, the asset is written down to fair value, which is determined based either on discounted cash flows or appraised value, depending on the nature of the asset.
Convertible Preferred Stock	Convertible Preferred Stock The Company, prior to the closing of its initial public offering (“IPO”) on September 23, 2015, classified its outstanding convertible preferred stock as temporary equity in the condensed consolidated balance sheet due to the existence of certain change in control events that were not solely within the Company’s control, including liquidation, sale or transfer of the Company, that could trigger the ability of the holders of the convertible preferred stock to call for redemption of shares. Upon the closing of the IPO, all outstanding shares of convertible preferred stock automatically converted into shares of common stock on a one -for-one basis.
Revenue Recognition	Revenue Recognition Revenue is comprised of product revenue net of returns, discounts, administration fees and sales rebates. The Company recognizes revenue when persuasive evidence of an arrangement exists, delivery has occurred, the sales price is fixed or determinable and collectability is reasonably assured. Evidence of an arrangement consists of customer orders and the Company typically considers delivery to have occurred once title and risk of loss has been transferred and the product has been delivered to the customer. The Company typically recognizes revenue when products are delivered to hospital customers or distributors. However, with respect to products that the Company consigns to hospitals, which primarily consist of coils, the Company recognizes revenue at the time hospitals utilize products in a procedure. Deferred revenue represents amounts that the Company has already invoiced its customers and are ultimately expected to be recognized as revenue, but for which not all revenue recognition criteria have been met. The Company had a deferred revenue balance of $0.8 million and $1.6 million , as of September 30, 2015 and December 31, 2014 , respectively. The Company’s terms and conditions permit product returns and exchanges, and it records returns reserves in the period when revenue is recognized. Estimates are based on actual historical returns over the prior three years and are recorded as reductions in revenue at the time of sale. Upon recognition, the Company reduces revenue and cost of revenue for the estimated return. Return rates can fluctuate over time, but are sufficiently predictable to allow the Company to estimate expected future product returns.
Cost of Revenue	Cost of Revenue Cost of revenue includes direct and indirect costs associated with the manufacture of the Company’s products. Direct costs include material and labor, while indirect costs include inbound freight charges, receiving costs, inspection and testing costs, warehousing costs, royalty expense and other labor and overhead costs incurred in the manufacturing of products. Cost of revenue also includes stock-based compensation, warranty replacement costs, cost of revenue related to product return reserves and excess and obsolete inventory write-downs.
Shipping Costs	Shipping Costs Shipping and handling costs charged to customers are recorded as revenue. Shipping and handling costs are included in cost of revenue.
Research and Development (R&D) Expenses	Research and Development (R&D) Expenses R&D costs primarily consist of product development, clinical and regulatory expenses, materials, depreciation and other costs associated with the development of the Company’s products. R&D costs also include related personnel and consultants’ salaries, benefits and related costs, including stock-based compensation. The Company expenses R&D costs as they are incurred. The Company’s clinical trial accruals are based on estimates of patient enrollment and related costs at clinical investigator sites. The Company estimates preclinical and clinical trial expenses based on the services performed pursuant to contracts with research institutions and clinical research organizations that conduct and manage preclinical studies and clinical trials on its behalf. In accruing service fees, the Company estimates the time period over which services will be performed and the level of patient enrollment and activity expended in each period. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual accordingly. Payments made to third parties under these arrangements in advance of the receipt of the related services are recorded as prepaid expenses until the services are rendered.
Advertising Costs	Advertising Costs Advertising costs are included in selling, general and administrative expenses and are expensed as incurred. Advertising costs consist primarily of trade show and booth costs, product demonstration, and marketing materials.
Stock-based Compensation	Stock-Based Compensation The Company recognizes the cost of stock-based compensation in the financial statements based upon fair value. The fair value of restricted stock awards is determined based on the number of units granted and the closing price of the Company’s common stock as of the grant date. The fair value of stock options is determined as of the grant date using the Black-Scholes option pricing model. The Company’s determination of the fair value of stock options is impacted by its common stock price as well as changes in assumptions regarding a number of highly complex and subjective variables. These variables include, but are not limited to, expected term that options will remain outstanding, expected common stock price volatility over the term of the option awards, risk-free interest rates and expected dividends. The fair value is recognized over the period during which an optionee is required to provide services in exchange for the option award, known as the requisite service period (usually the vesting period) on a straight-line basis. Stock-based compensation expense recognized at fair value includes the impact of estimated forfeitures. The Company estimates future forfeitures at the date of grant and revises the estimates, if necessary, in subsequent periods if actual forfeitures differ from those estimates. To the extent actual forfeiture results differ from the estimates, the difference is recorded as a cumulative adjustment in the period forfeiture estimates are revised. No compensation cost is recorded for options that do not vest. Equity instruments issued to non-employees are recorded at their fair value on the measurement date and are subject to periodic adjustments as the underlying equity instruments vest. The fair value of these equity instruments are expensed over the service period. Estimating the fair value of equity-settled awards as of the grant date using valuation models, such as the Black-Scholes option pricing model, is affected by assumptions regarding a number of complex variables. Changes in the assumptions can materially affect the fair value and ultimately how much stock-based compensation expense is recognized. These inputs are subjective and generally require significant analysis and judgment to develop. For all stock options granted to date, the Company estimated the volatility data based on a study of publicly traded industry peer companies. For purposes of identifying these peer companies, the Company considered the industry, stage of development, size and financial leverage of potential comparable companies. The risk-free interest rate is based on the yield available on U.S. Treasury zero-coupon issues similar in duration to the expected term of the equity-settled award. The Company uses the Staff Accounting Bulletin, or SAB, 110, simplified method to calculate the expected term, which is the average of the contractual term and vesting period.
Income Taxes	Income Taxes The Company accounts for income taxes using the asset and liability method, whereby deferred tax asset and liability account balances are determined based on differences between the 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. The Company provides a valuation allowance to reduce the net deferred tax assets to their estimated realizable value. The calculation of the Company’s current provision for income taxes involves the use of estimates, assumptions and judgments while taking into account current tax laws, interpretation of current tax laws and possible outcomes of future tax audits. The Company has established reserves to address potential exposures related to tax positions that could be challenged by tax authorities. Although the Company believes its estimates, assumptions and judgments to be reasonable, any changes in tax law or its interpretation of tax laws and the resolutions of potential tax audits could significantly impact the amounts provided for income taxes in the Company’s consolidated financial statements. During interim periods, the Company generally utilizes the estimated annual effective tax rate method which involves the use of forecasted information. The discrete method of calculating the estimated effective tax rate, on the other hand, involves the use of actual year-to-date information. For interim periods where the discrete method of calculating the estimated effective tax rate is determined to be a more reliable method than the estimated annual effective tax rate method, the Company will use the more reliable method to estimate its interim period income tax accrual. The calculation of the Company’s deferred tax asset balance involves the use of estimates, assumptions and judgments while taking into account estimates of the amounts and type of future taxable income. Actual future operating results and the underlying amount and type of income could differ materially from the Company’s estimates, assumptions and judgments thereby impacting the Company’s financial position and results of operations. The Company follows the guidance relating to accounting for uncertainty in income taxes, which prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of uncertain tax positions taken or expected to be taken in the Company’s income tax return, and also provides guidance on derecognition, classification, interest and penalties, accounting in interim periods, disclosure and transition. The Company includes interest and penalties related to unrecognized tax benefits within income tax expense in the accompanying consolidated statements of operations. The Company has not incurred any interest or penalties related to unrecognized tax benefits in any of the periods presented.
Comprehensive Income	Comprehensive Income The Company is required to display comprehensive income and its components as part of the Company’s consolidated financial statements. Comprehensive income consists of net income, unrealized gains on available-for-sale investments and the effects of foreign currency translation.
Deferred Offering Costs	Deferred Offering Costs Deferred offering costs, which primarily consisted of direct incremental legal and accounting fees were capitalized prior to the closing of the IPO. Upon closing of the IPO, the deferred offering costs were offset against IPO proceeds.
Net Income (Loss) Per Shae of Common Stock	Net Income (Loss) Per Share of Common Stock The Company, for the periods prior to the closing of the IPO, calculated its basic and diluted net income (loss) per share attributable to common stockholders in conformity with the two-class method required for companies with participating securities. Under the two-class method, the Company determined whether it had net income (loss) attributable to common stockholders, which included the results of operations less current period preferred stock non-cumulative dividends. If it was determined that the Company did have net income (loss) attributable to common stockholders during a period, the related undistributed earnings were then allocated between common stock and the preferred stock based on the weighted average number of shares outstanding during the period to determine the numerator for the basic net income (loss) per share attributable to common stockholders. In computing diluted net income attributable to common stockholders, undistributed earnings were re-allocated to reflect the potential impact of dilutive securities to determine the numerator for the diluted net income per share attributable to common stockholders. The Company’s basic net income (loss) per share attributable to common stockholders is calculated by dividing the net income (loss) by the weighted average number of shares of common stock outstanding for the period. The diluted net income per share attributable to common stockholders is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period. For purposes of this calculation, options to purchase common stock, restricted stock and common stock warrants are considered common stock equivalents.
Recently Issued Accounting Standards	Recently Issued Accounting Standards In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers , which outlines a comprehensive new revenue recognition model designed to depict the transfer of promised 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. The Company is currently evaluating the impact of this accounting standard. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers — Deferral of the Effective Date to defer the effective date by one year for annual reporting periods beginning after December 15, 2017, including interim reporting periods within that reporting period. Earlier adoption is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. In July 2015, the FASB issued ASU No. 2015-11, Simplifying the Measurement of Inventory , which requires an entity to measure most inventory at the lower of cost and net realizable value, thereby simplifying the current guidance under which an entity must measure inventory at the lower of cost or market. The accounting standard is effective prospectively for annual periods beginning after December 15, 2016, and interim periods therein. Early adoption is permitted as of the beginning of an interim or annual reporting period. The Company is currently evaluating the impact of this accounting standard

Fair Value of Financial Instr26

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Assets and Liabilities	The following table sets forth the Company’s financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2014 by level within the fair value hierarchy (in thousands): As of December 31, 2014 Level 1 Level 2 Level 3 Fair Value Financial Assets Cash equivalents: Money market funds $ 155 $ — $ — $ 155 Marketable investments: U.S. Agency securities — 6,006 — 6,006 U.S. Treasury 4,009 — — 4,009 Corporate bonds — 29,619 — 29,619 Mutual funds 8,619 — — 8,619 Total $ 12,783 $ 35,625 $ — $ 48,408

Balance Sheet Components (Table

Balance Sheet Components (Tables)	9 Months Ended
	Sep. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Allowance for Doubtful Accounts	The Company’s allowance for doubtful accounts comprised of the following (in thousands): Balance At Beginning Of Period Charged To Costs And Expenses Deductions Balance At End Of Period Allowance for Doubtful Accounts For the year ended December 31, 2014 $ 471 $ 150 $ (19 ) $ 602 For the nine months ended September 30, 2015 602 (108 ) — 494
Schedule of Prepaid Expenses and Other Current Assets	The Company’s prepaid expenses and other current assets comprised of the following (in thousands): September 30, December 31, Prepaid expenses $ 5,772 $ 3,130 Income tax receivable 318 1,654 Other current assets 177 331 Prepaid expenses and other current assets $ 6,267 $ 5,115
Schedule of Marketable Investments	The Company’s marketable investments as of December 31, 2014 were as follows (in thousands): Marketable Investments Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Agency securities $ 6,012 $ 3 $ (9 ) $ 6,006 U.S. Treasury 4,011 — (2 ) $ 4,009 Corporate bonds 29,834 4 (219 ) $ 29,619 Mutual funds 8,768 — (149 ) $ 8,619 Total $ 48,625 $ 7 $ (379 ) $ 48,253
Schedule of Contractual Maturities of Marketable Investments	The contractual maturities of the Company’s marketable investments as of December 31, 2014 were as follows (in thousands): December 31, 2014 Fair Value Due in one year $ 16,442 Due in one to five years 31,811 Total $ 48,253
Schedule of Inventories	The components of inventories consisted of the following (in thousands): September 30, December 31, Raw materials $ 9,477 $ 5,105 Work in process 1,244 543 Finished goods 39,603 27,803 Inventories $ 50,324 $ 33,451
Schedule of Property and Equipment, Net	Property and equipment, net consisted of the following (in thousands): September 30, December 31, Machinery and equipment $ 8,166 $ 5,089 Furniture and fixtures 2,004 519 Leasehold improvements 1,434 379 Software 744 599 Computers 565 153 Construction in progress 341 1,931 Total property and equipment 13,254 8,670 Less: Accumulated depreciation and amortization (4,608 ) (3,489 ) Property and equipment, net $ 8,646 $ 5,181
Schedule of Accrued Liabilities	The following table shows the components of accrued liabilities (in thousands): September 30, December 31, Payroll and employee-related expenses $ 12,850 $ 8,221 Sales return reserve 2,839 2,164 Preclinical and clinical trial cost 1,405 2,319 Deferred revenue 784 1,591 Product warranty 618 314 Sales tax payable 412 306 Income tax payable 54 332 Other accrued liabilities 5,291 3,228 Total accrued liabilities $ 24,253 $ 18,475
Schedule of Estimated Product Warranty Accrual	The estimated product warranty accrual was as follows (in thousands): September 30, December 31, Balance at the beginning of the period $ 314 $ 323 Accruals of warranties issued 545 149 Settlements of warranty claims (241 ) (158 ) Balance at the end of the period $ 618 $ 314

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments under Operating Leases	Future minimum lease payments under the non-cancelable operating leases as of September 30, 2015 are as follows (in thousands): Lease Payments Three Months Ending December 31, 2015 $ 766 Year Ending December 31: 2016 3,149 2017 3,145 2018 3,141 2019 3,223 2020 3,299 Thereafter 32,486 Total future minimum lease payments $ 49,209

Convertible Preferred Stock (Ta

Convertible Preferred Stock (Tables)	9 Months Ended
	Sep. 30, 2015
Temporary Equity Disclosure [Abstract]
Schedule of Convertible Preferred Stock	The convertible preferred stock at December 31, 2014 consisted of the following (in thousands, except shares): Series Shares Authorized Shares Issued and Outstanding Proceeds, Net of Issuance Costs Aggregate Liquidation Amount Series A Preferred Stock 1,000,000 1,000,000 $ 299 $ 554 Series B Preferred Stock 4,287,486 4,005,338 6,536 11,725 Series C Preferred Stock 4,388,715 4,168,218 13,266 22,238 Series D Preferred Stock 3,944,733 3,881,459 19,647 30,976 Series E Preferred Stock 1,973,684 1,909,940 14,507 21,609 Series F Preferred Stock 5,303,031 4,545,455 57,212 62,259 Undesignated 4,102,351 — — — Total preferred stock 25,000,000 19,510,410 $ 111,467 $ 149,361

Stock Option Plans (Tables)

Stock Option Plans (Tables)	9 Months Ended
	Sep. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Stock Option Activity	The following table summarizes the activity of stock options during the nine months ended September 30, 2015 : Number of Shares Weighted- Average Exercise Price Balance, December 31, 2014 2,900,676 $ 2.66 Options granted 1,809,400 21.47 Options exercised (938,456 ) 0.95 Options cancelled (5,526 ) 11.14 Balance, September 30, 2015 3,766,094 12.11
Summary of Unvested Restricted Stock Activity	The following table summarizes the activity of unvested restricted stock during the nine months ended September 30, 2015 : Number of Shares Weighted Average Grant Date Fair Value Unvested at December 31, 2014 367,126 $ 7.26 Granted 673,361 14.60 Vested (278,216 ) 11.77 Cancelled/Forfeited (3,000 ) 7.75 Unvested and expected to vest at September 30, 2015 759,271 12.12
Schedule of Stock-based Compensation Expense	The following table sets forth the stock-based compensation expense included in the consolidated statements of operations (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Cost of sales $ 141 $ 65 $ 271 $ 189 Research and development 100 23 282 70 Sales, general and administrative 1,269 284 4,573 815 $ 1,510 $ 372 $ 5,126 $ 1,074

Net Income (Loss) per Share o31

Net Income (Loss) per Share of Common Stock attributable to Common Stockholders (Tables)	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Reconciliation of the Numerator and Denominator used in the Calculation of the Basic and Diluted Earnings per Share	A reconciliation of the numerator and denominator used in the calculation of the basic and diluted net income (loss) per share attributable to common stockholders is as follows (in thousands except share and per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Net income (loss) per share: Numerator Net income $ 901 $ 172 $ 732 $ 1,829 Less: Deemed dividend paid to preferred stockholders upon repurchase — (6,344 ) — (6,344 ) Less: Undistributed income attributable to preferred stockholders (625 ) — (557 ) — Add: Undistributed loss attributable to preferred stockholders — 4,980 — 3,582 Net income (loss) attributable to common stockholders—basic and diluted $ 276 $ (1,192 ) $ 175 $ (933 ) Denominator Weighted average shares used to compute net income (loss) attributable to common stockholders —Basic 7,853,730 4,688,045 5,962,031 4,577,725 Potential dilutive options, as calculated using treasury stock method 1,979,194 — 2,362,685 — Potential dilutive restricted stock, as calculated using treasury stock method 356,324 — 169,935 — Weighted average shares used to compute net income (loss) attributable to common stockholders —Diluted 10,189,248 4,688,045 8,494,651 4,577,725 Net income (loss) per share attributable to common stockholders —Basic $ 0.04 $ (0.25 ) $ 0.03 $ (0.20 ) —Diluted $ 0.03 $ (0.25 ) $ 0.02 $ (0.20 )
Schedule of Antidilutive Securities Excluded from Computation of Earnings per Share	The following outstanding shares of potentially dilutive securities were excluded from the computation of diluted net income (loss) per share of common stock for the periods presented, because the effect of including them would have been anti-dilutive: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Options to purchase common stock 1,321,250 2,976,992 1,321,250 2,976,992 Restricted stock 6,500 368,793 6,500 368,793 Common stock warrants — 75,972 — 75,972 Total 1,327,750 3,421,757 1,327,750 3,421,757

Geographic Areas and Product 32

Geographic Areas and Product Sales (Tables)	9 Months Ended
	Sep. 30, 2015
Segment Reporting [Abstract]
Revenue by Geographic Area	The Company’s revenue by geographic area, based on the destination to which the Company ships its products, was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 United States $ 35,394 $ 22,305 $ 89,364 $ 59,281 Japan 5,420 3,467 14,030 10,796 Other International 9,602 6,692 28,285 20,030 Total $ 50,416 $ 32,464 $ 131,679 $ 90,107
Revenue by Product Category	The following table sets forth revenue by product category (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Neuro $ 36,309 $ 26,988 $ 102,363 $ 77,056 Peripheral Vascular 14,107 5,476 29,316 13,051 Total $ 50,416 $ 32,464 $ 131,679 $ 90,107

Organization and Description 33

Organization and Description of Business (Details)	9 Months Ended
	Sep. 30, 2015market
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of major markets	2

Summary of Significant Accoun34

Summary of Significant Accounting Policies - Additional Disclosures (Details)	Sep. 23, 2015	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)	Sep. 30, 2015USD ($)segmentactivity	Sep. 30, 2014USD ($)	Dec. 31, 2014USD ($)
Accounting Policies [Abstract]
Number of business activities | activity				1
Number of operating segments | segment				1
Foreign currency transaction gains		$ 100,000	$ 100,000	$ 11,000	$ 200,000
Other-than-temporary impairments for marketable investments		0	0	0	0
Inventory write downs		400,000	900,000	704,000	1,398,000
Impairment of long-lived assets		0	0	0	0
Preferred stock conversion to common stock, conversion ratio	1
Deferred revenue		800,000		800,000		$ 1,600,000
Advertising expense		$ 100,000	$ 100,000	$ 400,000	$ 200,000

Summary of Significant Accoun35

Summary of Significant Accounting Policies - Concentration of Credit Risk (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015USD ($)	Sep. 30, 2014	Sep. 30, 2015USD ($)financial_instituion	Sep. 30, 2014	Dec. 31, 2014USD ($)
Customer Concentration Risk | Revenue | One Major Customer [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	11.00%	11.00%	11.00%	12.00%
United States
Concentration Risk [Line Items]
Number of financial institutions holding cash in excess of federally insured limits			1
Foreign Countries
Concentration Risk [Line Items]
Cash that is not federally insured | $	$ 2.3		$ 2.3		$ 0.8

Summary of Significant Accoun36

Summary of Significant Accounting Policies - Property and Equipment, Net (Details)	9 Months Ended
	Sep. 30, 2015
Property and equipment excluding leasehold improvements
Property, Plant and Equipment [Line Items]
Useful life of property and equipment	5 years

Initial Public Offering (IPO) (

Initial Public Offering (IPO) (Details) $ / shares in Units, $ in Thousands	Sep. 23, 2015USD ($)$ / sharesshares	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)
Class of Stock [Line Items]
Proceeds from issuance of common stock issued in initial public offering, net of issuance costs		$ 125,916	$ 0
Preferred stock conversion to common stock, number of shares | shares	19,510,410
Preferred stock conversion to common stock, conversion ratio	1
Initial Public Offering
Class of Stock [Line Items]
Shares issued, shares | shares	4,600,000
Shares issued, price per share (in dollars per share) | $ / shares	$ 30
Proceeds from issuance of common stock issued in initial public offering, net of issuance costs	$ 124,800
Payments for underwriting discounts and commissions	9,700
Payments for other offering expenses	$ 3,600

Fair Value of Financial Instr38

Fair Value of Financial Instruments (Details) - Recurring $ in Thousands	Dec. 31, 2014USD ($)
Financial Assets
Total	$ 48,408
U.S. Agency securities
Financial Assets
Marketable investments	6,006
U.S. Treasury
Financial Assets
Marketable investments	4,009
Corporate bonds
Financial Assets
Marketable investments	29,619
Mutual funds
Financial Assets
Marketable investments	8,619
Money market funds
Financial Assets
Money market funds	155
Level 1
Financial Assets
Total	12,783
Level 1 | U.S. Agency securities
Financial Assets
Marketable investments	0
Level 1 | U.S. Treasury
Financial Assets
Marketable investments	4,009
Level 1 | Corporate bonds
Financial Assets
Marketable investments	0
Level 1 | Mutual funds
Financial Assets
Marketable investments	8,619
Level 1 | Money market funds
Financial Assets
Money market funds	155
Level 2
Financial Assets
Total	35,625
Level 2 | U.S. Agency securities
Financial Assets
Marketable investments	6,006
Level 2 | U.S. Treasury
Financial Assets
Marketable investments	0
Level 2 | Corporate bonds
Financial Assets
Marketable investments	29,619
Level 2 | Mutual funds
Financial Assets
Marketable investments	0
Level 2 | Money market funds
Financial Assets
Money market funds	0
Level 3
Financial Assets
Total	0
Level 3 | U.S. Agency securities
Financial Assets
Marketable investments	0
Level 3 | U.S. Treasury
Financial Assets
Marketable investments	0
Level 3 | Corporate bonds
Financial Assets
Marketable investments	0
Level 3 | Mutual funds
Financial Assets
Marketable investments	0
Level 3 | Money market funds
Financial Assets
Money market funds	$ 0

Balance Sheet Components - Acco

Balance Sheet Components - Accounts Receivable, Net (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of period	$ 602	$ 471	$ 471
Charged to costs and expenses	(108)	$ 172	150
Deductions	0		(19)
Balance at end of period	$ 494		$ 602

Balance Sheet Components - Prep

Balance Sheet Components - Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Prepaid expenses	$ 5,772	$ 3,130
Income tax receivable	318	1,654
Other current assets	177	331
Prepaid expenses and other current assets	$ 6,267	$ 5,115

Balance Sheet Components - Gain

Balance Sheet Components - Gains and Losses of Marketable Investments (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Cost		$ 48,625
Gross unrealized gains		7
Gross unrealized losses		(379)
Fair value	$ 0	48,253
Realized loss on sale of marketable investments	$ 500
U.S. Agency securities
Schedule of Available-for-sale Securities [Line Items]
Cost		6,012
Gross unrealized gains		3
Gross unrealized losses		(9)
Fair value		6,006
U.S. Treasury
Schedule of Available-for-sale Securities [Line Items]
Cost		4,011
Gross unrealized gains		0
Gross unrealized losses		(2)
Fair value		4,009
Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Cost		29,834
Gross unrealized gains		4
Gross unrealized losses		(219)
Fair value		29,619
Mutual funds
Schedule of Available-for-sale Securities [Line Items]
Cost		8,768
Gross unrealized gains		0
Gross unrealized losses		(149)
Fair value		$ 8,619

Balance Sheet Components - Cont

Balance Sheet Components - Contractual Maturities of Marketable Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Due in one year		$ 16,442
Due in one to five years		31,811
Total	$ 0	$ 48,253

Balance Sheet Components - Inve

Balance Sheet Components - Inventories (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Raw materials	$ 9,477	$ 5,105
Work in process	1,244	543
Finished goods	39,603	27,803
Inventories	$ 50,324	$ 33,451

Balance Sheet Components - Prop

Balance Sheet Components - Property and Equipment, Net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 13,254		$ 13,254		$ 8,670
Less: Accumulated depreciation and amortization	(4,608)		(4,608)		(3,489)
Property and equipment, net	8,646		8,646		5,181
Depreciation and amortization expense	500	$ 200	1,227	$ 520
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	8,166		8,166		5,089
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	2,004		2,004		519
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	1,434		1,434		379
Software
Property, Plant and Equipment [Line Items]
Total property and equipment	744		744		599
Computers
Property, Plant and Equipment [Line Items]
Total property and equipment	565		565		153
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 341		$ 341		$ 1,931

Balance Sheet Components - Accr

Balance Sheet Components - Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Payroll and employee-related expenses	$ 12,850	$ 8,221
Sales return reserve	2,839	2,164
Preclinical and clinical trial cost	1,405	2,319
Deferred revenue	784	1,591
Product warranty	618	314
Sales tax payable	412	306
Income tax payable	54	332
Other accrued liabilities	5,291	3,228
Total accrued liabilities	$ 24,253	$ 18,475

Balance Sheet Components - Prod

Balance Sheet Components - Product Warranty (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Product Warranty, Increase (Decrease) [Roll Forward]
Balance at the beginning of the period	$ 314	$ 323
Accruals of warranties issued	545	149
Settlements of warranty claims	(241)	(158)
Balance at the end of the period	$ 618	$ 314

Credit Facility (Details)

Credit Facility (Details) - Revolving credit facility - Wells Fargo Bank, National Association	1 Months Ended
	May. 31, 2012USD ($)
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 15,000,000
One-month London Inter-Bank Offered Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.75%

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($)	1 Months Ended		9 Months Ended
	Jul. 31, 2011	Mar. 31, 2005	Sep. 30, 2015	Dec. 31, 2014
Related Party Transaction [Line Items]
Options exercised (shares)			938,456
Promissory notes receivable			$ 26,000	$ 117,000
Stockholders
Related Party Transaction [Line Items]
Promissory notes receivable			$ 25,850	$ 100,000
Stockholders | March 2005 Transaction
Related Party Transaction [Line Items]
Options exercised (shares)		250,000
Interest rate on promissory notes		2.92%
Promissory notes receivable		$ 21,250
Stockholders | July 2011 Transaction
Related Party Transaction [Line Items]
Options exercised (shares)	5,000
Promissory notes receivable	$ 4,600

Commitments and Contingencies -

Commitments and Contingencies - Lease and Purchase Commitments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]
Rent expense	$ 900	$ 400	$ 2,300	$ 1,300
Future minimum lease payments under non-cancelable operating leases
Three Months Ending December 31, 2015	766		766
2,016	3,149		3,149
2,017	3,145		3,145
2,018	3,141		3,141
2,019	3,223		3,223
2,020	3,299		3,299
Thereafter	32,486		32,486
Total future minimum lease payments	49,209		49,209
Purchase obligations	$ 11,700		$ 11,700

Commitments and Contingencies50

Commitments and Contingencies - Royalty Obligations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Cost of Sales
Other Commitments [Line Items]
Royalty expense	$ 0.6	$ 0.3	$ 1.4	$ 0.8
Royalty Agreement, March 2005
Other Commitments [Line Items]
Minimum annual royalty payments	$ 0.1		$ 0.1		$ 0.1
Term of royalty agreement			15 years
Royalty Agreement, April 2012
Other Commitments [Line Items]
Royalty as a percent of sales			5.00%
Term of royalty agreement			15 years
Royalty Agreement, April 2015
Other Commitments [Line Items]
Royalty as a percent of sales			2.00%
Term of royalty agreement			20 years

Commitments and Contingencies51

Commitments and Contingencies - Litigation (Details) $ in Millions	9 Months Ended
	Sep. 30, 2015USD ($)
Damages from Product
Loss Contingencies [Line Items]
Damages sought, value	$ 35

Convertible Preferred Stock (De

Convertible Preferred Stock (Details) $ in Thousands	Sep. 23, 2015shares	Sep. 30, 2015USD ($)shares	Dec. 31, 2014USD ($)shares
Temporary Equity [Line Items]
Shares authorized		0	25,000,000
Shares issued		0	19,510,410
Shares outstanding		0	19,510,410
Proceeds net of issuance costs | $		$ 0	$ 111,467
Aggregate liquidation amount | $			$ 149,361
Preferred stock conversion to common stock, number of shares	19,510,410
Preferred stock conversion to common stock, conversion ratio	1
Series A Preferred Stock
Temporary Equity [Line Items]
Shares authorized			1,000,000
Shares issued			1,000,000
Shares outstanding			1,000,000
Proceeds net of issuance costs | $			$ 299
Aggregate liquidation amount | $			$ 554
Series B Preferred Stock
Temporary Equity [Line Items]
Shares authorized			4,287,486
Shares issued			4,005,338
Shares outstanding			4,005,338
Proceeds net of issuance costs | $			$ 6,536
Aggregate liquidation amount | $			$ 11,725
Series C Preferred Stock
Temporary Equity [Line Items]
Shares authorized			4,388,715
Shares issued			4,168,218
Shares outstanding			4,168,218
Proceeds net of issuance costs | $			$ 13,266
Aggregate liquidation amount | $			$ 22,238
Series D Preferred Stock
Temporary Equity [Line Items]
Shares authorized			3,944,733
Shares issued			3,881,459
Shares outstanding			3,881,459
Proceeds net of issuance costs | $			$ 19,647
Aggregate liquidation amount | $			$ 30,976
Series E Preferred Stock
Temporary Equity [Line Items]
Shares authorized			1,973,684
Shares issued			1,909,940
Shares outstanding			1,909,940
Proceeds net of issuance costs | $			$ 14,507
Aggregate liquidation amount | $			$ 21,609
Series F Preferred Stock
Temporary Equity [Line Items]
Shares authorized			5,303,031
Shares issued			4,545,455
Shares outstanding			4,545,455
Proceeds net of issuance costs | $			$ 57,212
Aggregate liquidation amount | $			$ 62,259
Undesignated
Temporary Equity [Line Items]
Shares authorized			4,102,351
Shares issued			0
Shares outstanding			0
Proceeds net of issuance costs | $			$ 0
Aggregate liquidation amount | $			$ 0

Common Stock (Details)

Common Stock (Details)	9 Months Ended
	Sep. 30, 2015vote
Equity [Abstract]
Common stock, number of votes per share	1

Warrants (Details)

Warrants (Details)	12 Months Ended
	Dec. 31, 2004$ / sharesshares
Equity [Abstract]
Number of shares of common stock called by warrants | shares	211,138
Purchase price of common stock (in dollars per share)	$ 0.01
Term of warrants	10 years

Stock Option Plans - Stock Plan

Stock Option Plans - Stock Plans (Details) - USD ($)	9 Months Ended
	Sep. 30, 2015	Sep. 17, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options outstanding (shares)	3,766,094		2,900,676
Number of options unvested and subject to repurchase (shares)	15,662		33,081
Liability relating to cash received from employees for exercise of unvested options	$ 100,000		$ 100,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of awards outstanding (shares)	759,271		367,126
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved for future issuance (shares)		600,000
Minimum percent of eligible compensation per pay period to be used to purchase shares under plan	1.00%
Maximum percent of eligible compensation per pay period to be used to purchase shares under plan	15.00%
Purchase price of common stock, percent of fair market value	85.00%
Maximum number of shares that may be purchased by any one employee	2,000
Maximum value of shares that may be purchased by any one employee	$ 25,000
2005 Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted since inception of plan (shares)	5,431,017		5,431,017
Number of options outstanding (shares)	1,767,324		2,707,176
Number of options unvested and subject to repurchase (shares)	15,662		33,081
2005 Stock Plan | Stock Options | Vesting, First Year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rate	25.00%
2005 Stock Plan | Stock Options | Vesting, After First Year, Monthly Vesting Rate
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rate	2.08%
2005 Stock Plan | Incentive Stock Options (ISO)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Minimum voting rights for determination of exercise price, percent	10.00%
Minimum exercise price, percent over fair market value	110.00%
2005 Stock Plan | Incentive Stock Options (ISO) | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of award	5 years
2005 Stock Plan | Other Options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of award	10 years
2011 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted since inception of plan (shares)	145,000		145,000
Number of options outstanding (shares)	145,000		145,000
2011 Equity Incentive Plan | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of award	10 years
Award vesting period	4 years
2011 Equity Incentive Plan | Incentive Stock Options (ISO)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Minimum voting rights for determination of exercise price, percent	10.00%
Minimum exercise price, percent over fair market value	110.00%
2011 Equity Incentive Plan | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted since inception of plan (shares)	505,000		505,000
Number of awards outstanding (shares)	249,125		367,126
Awards forfeited since inception of plan (shares)	4,667		1,667
2014 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted since inception of plan (shares)	1,857,900		48,500
Number of options outstanding (shares)	1,853,770		48,500
Options forfeited since inception of plan (shares)	4,130		1,000
2014 Equity Incentive Plan | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted since inception of plan (shares)	673,361		0
Number of awards outstanding (shares)	510,146		0

Stock Option Plans - Stock Opti

Stock Option Plans - Stock Option Activity (Details)	9 Months Ended
	Sep. 30, 2015$ / sharesshares
Number of Shares
Beginning balance (shares) | shares	2,900,676
Options granted (shares) | shares	1,809,400
Options exercised (shares) | shares	(938,456)
Options cancelled (shares) | shares	(5,526)
Ending balance (shares) | shares	3,766,094
Weighted Average Exercise Price
Beginning balance (in dollars per share)	$ 2.66
Options granted (in dollars per share)	21.47
Options exercised (in dollars per share)	0.95
Options cancelled (in dollars per share)	11.14
Ending balance (in dollars per share)	12.11
Weighted average grant date fair value of employee stock options granted (in dollars per share)	$ 9.69

Stock Option Plans - Restricted

Stock Option Plans - Restricted Stock Activity (Details) - Restricted Stock	9 Months Ended
	Sep. 30, 2015$ / sharesshares
Number of shares
Unvested beginning balance (shares) | shares	367,126
Granted (shares) | shares	673,361
Vested (shares) | shares	(278,216)
Cancelled/Forfeited (shares) | shares	(3,000)
Unvested and expected to vest ending balance (shares) | shares	759,271
Weighted Average Grant Date Fair Value
Unvested beginning balance (in dollars per share)	$ 7.26
Granted (in dollars per share)	14.60
Vested (in dollars per share)	11.77
Cancelled/Forfeited (in dollars per share)	7.75
Unvested and expected to vest ending balance (in dollars per share)	$ 12.12

Stock Option Plans - Stock-base

Stock Option Plans - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Unrecognized compensation cost related to unvested share-based compensation arrangements	$ 25,600		$ 25,600
Unrecognized compensation cost, expected recognition period			2 years 2 months
Stock-based compensation expense	1,510	$ 372	$ 5,126	$ 1,074
Cost of sales
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	141	65	271	189
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	100	23	282	70
Sales, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 1,269	$ 284	$ 4,573	$ 815

Common and Preferred Stock Re59

Common and Preferred Stock Repurchase (Details) - USD ($)	1 Months Ended		2 Months Ended	9 Months Ended
	Jul. 31, 2014	May. 31, 2014	Jun. 30, 2014	Sep. 30, 2015
Class of Stock [Line Items]
Share repurchase program, price per share (in dollars per share)		$ 13.20
Value of shares authorized to be repurchased		$ 2,000,000
Value of shares repurchased and retired				$ 342,000
Stock Options
Class of Stock [Line Items]
Number of shares authorized to be repurchased		45,000
Common Stock
Class of Stock [Line Items]
Number of shares authorized to be repurchased		70,612
Shares repurchased and retired				23,650
Common Stock | Stock Options
Class of Stock [Line Items]
Excess between the purchase and issuance price			$ 500,000
Preferred Stock
Class of Stock [Line Items]
Number of shares authorized to be repurchased		45,611
Share repurchase program, price per share (in dollars per share)	$ 13.20
Excess between the purchase and issuance price	$ 5,800,000		$ 500,000
Shares repurchased and retired	584,052
Value of shares repurchased and retired	$ 7,700,000

Income Taxes (Details)

Income Taxes (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Tax Disclosure [Abstract]
Effective tax rate	56.80%	56.90%	65.90%	32.80%

Net Income (Loss) per Share o61

Net Income (Loss) per Share of Common Stock attributable to Common Stockholders - Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Numerator
Net income	$ 901	$ 172	$ 732	$ 1,829
Less: Deemed dividend paid to preferred stockholders upon repurchase	0	(6,344)	0	(6,344)
Undistributed (income) loss attributable to preferred stockholders, basic	(625)	4,980	(557)	3,582
Undistributed (income) loss attributable to preferred stockholders, diluted	(625)	4,980	(557)	3,582
Net income (loss) attributable to common stockholders—basic	276	(1,192)	175	(933)
Net income (loss) attributable to common stockholders—diluted	$ 276	$ (1,192)	$ 175	$ (933)
Denominator
Weighted average shares used to compute net income (loss) per share attributable to common stockholders — Basic	7,853,730	4,688,045	5,962,031	4,577,725
Weighted average shares used to compute net income (loss) per share attributable to common stockholders — Diluted	10,189,248	4,688,045	8,494,651	4,577,725
Net income (loss) per share attributable to common stockholders — Basic (in dollars per share)	$ 0.04	$ (0.25)	$ 0.03	$ (0.20)
Net income (loss) per share attributable to common stockholders — Diluted (in dollars per share)	$ 0.03	$ (0.25)	$ 0.02	$ (0.20)
Stock Options
Denominator
Potential dilutive share-based payment awards, as calculated using treasury stock method	1,979,194	0	2,362,685	0
Restricted Stock
Denominator
Potential dilutive restricted stock, as calculated using treasury stock method	356,324	0	169,935	0

Net Income (Loss) per Share o62

Net Income (Loss) per Share of Common Stock attributable to Common Stockholders - Antidilutive Securities (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from the computation of earnings per share	1,327,750	3,421,757	1,327,750	3,421,757
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from the computation of earnings per share	1,321,250	2,976,992	1,321,250	2,976,992
Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from the computation of earnings per share	6,500	368,793	6,500	368,793
Common stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from the computation of earnings per share	0	75,972	0	75,972

Geographic Areas and Product 63

Geographic Areas and Product Sales - Revenue by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 50,416	$ 32,464	$ 131,679	$ 90,107
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	35,394	22,305	89,364	59,281
Japan
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	5,420	3,467	14,030	10,796
Other International
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 9,602	$ 6,692	$ 28,285	$ 20,030

Geographic Areas and Product 64

Geographic Areas and Product Sales - Revenue by Product Category (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenue from External Customer [Line Items]
Revenue	$ 50,416	$ 32,464	$ 131,679	$ 90,107
Neuro
Revenue from External Customer [Line Items]
Revenue	36,309	26,988	102,363	77,056
Peripheral Vascular
Revenue from External Customer [Line Items]
Revenue	$ 14,107	$ 5,476	$ 29,316	$ 13,051