Inogen (INGN) 10-Q 7 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 31, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Trading Symbol	INGN
Entity Registrant Name	Inogen Inc
Entity Central Index Key	1,294,133
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		20,870,357

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 129,693	$ 92,851
Marketable securities	33,395	21,033
Accounts receivable, net	34,699	30,828
Inventories, net	16,855	14,343
Deferred cost of revenue	358	398
Income tax receivable	1,593	433
Prepaid expenses and other current assets	3,186	1,659
Total current assets	219,779	161,545
Property and equipment
Rental equipment, net	51,010	54,582
Manufacturing equipment and tooling	6,693	6,133
Computer equipment and software	5,313	4,705
Furniture and equipment	781	779
Leasehold improvements	1,552	816
Land and building	125	125
Construction in process	265	75
Total property and equipment	65,739	67,215
Less accumulated depreciation	(44,788)	(42,016)
Property and equipment, net	20,951	25,199
Goodwill	2,330
Intangible assets, net	1,650	241
Deferred tax asset - noncurrent	24,619	26,654
Other assets	512	410
Total assets	269,841	214,049
Current liabilities
Accounts payable and accrued expenses	22,367	12,795
Accrued payroll	6,871	6,123
Warranty reserve - current	2,298	1,688
Deferred revenue - current	3,646	2,239
Income tax payable	251
Total current liabilities	35,433	22,845
Long-term liabilities
Warranty reserve - noncurrent	3,269	1,792
Deferred revenue - noncurrent	8,622	7,042
Deferred tax liability - noncurrent	414
Other noncurrent liabilities	817	282
Total liabilities	48,555	31,961
Commitments and contingencies (Note 8)
Stockholders' equity
Common stock, $0.001 par value per share; 200,000,000 authorized; 20,851,696 and 20,389,860 shares issued and outstanding as of September 30, 2017 and December 31, 2016, respectively	21	20
Additional paid-in capital	211,817	194,466
Retained earnings (accumulated deficit)	9,245	(12,363)
Accumulated other comprehensive income (loss)	203	(35)
Total stockholders' equity	221,286	182,088
Total liabilities and stockholders' equity	$ 269,841	$ 214,049

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	20,851,696	20,389,860
Common stock, shares outstanding	20,851,696	20,389,860

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenue
Sales revenue	$ 63,137	$ 47,177	$ 167,141	$ 125,566
Rental revenue	5,893	7,245	18,510	26,412
Total revenue	69,030	54,422	185,651	151,978
Cost of revenue
Cost of sales revenue	31,401	24,271	81,307	63,824
Cost of rental revenue, including depreciation of $2,366 and $2,878 for the three months ended and $7,577 and $8,733 for the nine months ended, respectively	4,459	5,023	13,863	15,532
Total cost of revenue	35,860	29,294	95,170	79,356
Gross profit
Gross profit-sales revenue	31,736	22,906	85,834	61,742
Gross profit-rental revenue	1,434	2,222	4,647	10,880
Total gross profit	33,170	25,128	90,481	72,622
Operating expense
Research and development	1,375	1,350	3,944	3,897
Sales and marketing	13,095	9,679	35,569	28,220
General and administrative	10,368	8,702	28,568	23,812
Total operating expense	24,838	19,731	68,081	55,929
Income from operations	8,332	5,397	22,400	16,693
Other income (expense)
Interest expense		(1)		(6)
Interest income	221	61	468	126
Other income (expense)	264	(8)	994	78
Total other income, net	485	52	1,462	198
Income before provision for income taxes	8,817	5,449	23,862	16,891
Provision for income taxes	1,479	203	2,254	1,632
Net income	7,338	5,246	21,608	15,259
Other comprehensive income (loss), net of tax
Change in foreign currency translation adjustment	115		312
Change in net unrealized gains (losses) on foreign currency hedging	(196)	10	(442)	(24)
Less: reclassification adjustment for net (gains) losses included in net income	305	2	297	51
Total net change in unrealized gains (losses) on foreign currency hedging	109	12	(145)	27
Change in net unrealized gains (losses) on available-for-sale investments	13	(4)	71	16
Total other comprehensive income, net of tax	237	8	238	43
Comprehensive income	$ 7,575	$ 5,254	$ 21,846	$ 15,302
Basic net income per share attributable to common stockholders (Note 5)	$ 0.35	$ 0.26	$ 1.05	$ 0.76
Diluted net income per share attributable to common stockholders (Note 5)	$ 0.33	$ 0.25	$ 0.99	$ 0.73
Weighted-average number of shares used in calculating net income per share attributable to common stockholders:
Basic common shares	20,753,789	20,157,688	20,622,848	19,986,544
Diluted common shares	21,998,660	21,182,587	21,832,544	21,000,945

Consolidated Statements of Com5

Consolidated Statements of Comprehensive Income (Parenthetical) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Depreciation	$ 2,366	$ 2,878	$ 7,577	$ 8,733

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Retained earnings (accumulated deficit)	Accumulated other comprehensive income (loss)
Beginning Balance at Dec. 31, 2015	$ 134,018	$ 20	$ 179,143	$ (45,108)	$ (37)
Beginning Balance, shares at Dec. 31, 2015		19,782,403
Cumulative effect of change in accounting principle	12,226			12,226
Stock-based compensation	5,404		5,404
Employee stock purchases	1,055		1,055
Employee stock purchases, shares		37,378
Stock options exercised	4,600		4,600
Stock options exercised, shares		424,462
Net income	15,259			15,259
Other comprehensive income	43				43
Ending Balance at Sep. 30, 2016	172,605	$ 20	190,202	(17,623)	6
Ending Balance, shares at Sep. 30, 2016		20,244,243
Beginning Balance at Dec. 31, 2016	182,088	$ 20	194,466	(12,363)	(35)
Beginning Balance, shares at Dec. 31, 2016		20,389,860
Stock-based compensation	6,630		6,630
Stock-based compensation, shares		41,574
Employee stock purchases	1,379		1,379
Employee stock purchases, shares		24,523
Stock options exercised	$ 9,343	$ 1	9,342
Stock options exercised, shares	395,739	395,739
Net income	$ 21,608			21,608
Other comprehensive income	238				238
Ending Balance at Sep. 30, 2017	$ 221,286	$ 21	$ 211,817	$ 9,245	$ 203
Ending Balance, shares at Sep. 30, 2017		20,851,696

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities
Net income	$ 21,608	$ 15,259
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	9,257	10,290
Loss on rental units and other fixed assets	934	891
Gain on sale of former rental assets	(62)	(224)
Provision for sales returns and doubtful accounts	10,319	8,177
Provision for rental revenue adjustments	3,828	7,783
Provision for inventory obsolescence and other inventory losses, net of recoveries	222	141
Stock-based compensation expense	6,630	5,404
Deferred tax assets	2,035	1,653
Changes in operating assets and liabilities:
Accounts receivable	(16,826)	(25,812)
Inventories	(3,481)	(9,220)
Deferred cost of revenue	40	(42)
Income tax receivable	(1,155)	546
Prepaid expenses and other current assets	(1,421)	(600)
Accounts payable and accrued expenses	9,103	7,801
Accrued payroll	717	573
Warranty reserve	2,085	1,424
Deferred revenue	2,987	1,856
Income tax payable	131	(11)
Other noncurrent liabilities	535	(37)
Net cash provided by operating activities	47,486	25,852
Cash flows from investing activities
Purchases of available-for-sale investments	(35,367)	(26,321)
Maturities of available-for-sale investments	23,076	20,799
Investment in intangible assets	(15)	(112)
Investment in property and equipment	(2,083)	(1,483)
Production and purchase of rental equipment	(2,682)	(4,588)
Proceeds from sale of former assets	129	328
Payment for acquisition, net of cash acquired	(4,447)
Net cash used in investing activities	(21,389)	(11,377)
Cash flows from financing activities
Proceeds from stock options exercised	9,343	4,600
Proceeds from employee stock purchases	1,379	1,055
Repayment of debt from investment in intangible assets		(235)
Net cash provided by financing activities	10,722	5,420
Effect of exchange rates on cash	23	8
Net increase in cash and cash equivalents	36,842	19,903
Cash and cash equivalents, beginning of period	92,851	66,106
Cash and cash equivalents, end of period	129,693	86,009
Supplemental disclosures of cash flow information
Cash paid during the period for interest		9
Cash paid (received) during the period for income taxes, net of refunds received	1,164	$ (533)
Supplemental disclosure of non-cash transactions
Property and equipment in accounts payable and accrued liabilities	$ 104

Business Overview

Business Overview	9 Months Ended
	Sep. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Business Overview	1. Business overview Inogen, Inc. (Company or Inogen) was incorporated in Delaware on November 27, 2001. The Company is a medical technology company that primarily develops, manufactures and markets innovative portable oxygen concentrators used to deliver supplemental long-term oxygen therapy to patients suffering from chronic respiratory conditions. Traditionally, these patients have relied on stationary oxygen concentrator systems for use in the home and oxygen tanks or cylinders for mobile use, which the Company calls the delivery model. The tanks and cylinders must be delivered regularly and have a finite amount of oxygen, which requires patients to plan activities outside of their homes around delivery schedules and a finite oxygen supply. Additionally, patients must attach long, cumbersome tubing to their stationary concentrators simply to enable mobility within their homes. The Company’s proprietary Inogen One ® ® ® ® Portable oxygen concentrators represented the fastest-growing segment of the Medicare oxygen therapy market between 2012 and 2016. The Company estimates based on 2016 Medicare data that patients using portable oxygen concentrators represent approximately 9.1% of the total addressable oxygen market in the United States, although the Medicare data does not account for private insurance and cash-pay sales into the market. Based on 2016 industry data, the Company believes it was the leading worldwide manufacturer of portable oxygen concentrators. The Company believes it is the only manufacturer of portable oxygen concentrators that employs a direct-to-consumer strategy in the United States, meaning the Company markets its products to patients, processes their physician paperwork, provides clinical support as needed and bills Medicare or insurance on their behalf. To pursue a direct-to-consumer strategy, the Company’s manufacturing competitors would need to meet national accreditation and state-by-state licensing requirements and secure Medicare billing privileges, including Medicare competitive bidding contracts, as well as compete with the home medical equipment providers who many of the Company’s manufacturing competitors sell to across their entire homecare business. Since adopting the Company’s direct-to-consumer strategy in 2009 following its acquisition of Comfort Life Medical Supply, LLC, which had an active Medicare billing number but few other assets and limited business activities, the Company has directly sold or rented more than 327,000 of its Inogen oxygen concentrators as of September 30, 2017. The Company incorporated Inogen Europe Holding B.V., a Dutch limited liability company, on April 13, 2017. The Company owns all outstanding stock of Inogen Europe Holding B.V., which became a wholly owned subsidiary of the Company. On May 4, 2017, the Company, through its wholly owned subsidiary, Inogen Europe Holding B.V., acquired all issued and outstanding capital stock of MedSupport Systems B.V. (MedSupport) for approximately $5,831 comprised of $5,779 of cash paid at closing and estimated net working capital adjustments of approximately $52 to be paid in the fourth quarter of 2017 classified in accounts payable and accrued expenses. In aggregate, $1,337 was cash acquired, $1,529 was attributed to intangible assets, $2,154 was attributed to goodwill, and $811 was attributed to net assets assumed. MedSupport is engaged in the business of importing and distributing medical devices throughout Europe. The acquisition allows the Company to add a European customer support and repair site in the Netherlands and is currently operating as Inogen Europe B.V. Goodwill associated with this acquisition is not deductible for tax purposes in the Netherlands. Acquisition expenses of approximately $370 were expensed in 2017 and are classified within general and administrative expense. The Company's allocation of the purchase price remains incomplete and any measurement period adjustments that result from the finalization of the purchase price allocation will be recorded retrospectively to the acquisition date. Pro forma results of operations for this acquisition have not been presented because they are not material to the consolidated results of operations, either individually or in aggregate.

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	2. Basis of presentation and summary of significant accounting policies The accompanying consolidated financial statements are unaudited. The balance sheet at December 31, 2016 has been derived from the audited financial statements of the Company. The accompanying consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (U.S. GAAP) for interim financial information, and in management’s opinion, includes all adjustments, consisting of only normal recurring adjustments, necessary for the fair statement of the Company’s financial position, its results of operations, stockholders’ equity and cash flows for the interim periods presented. The results of operations for the three and nine months ended September 30, 2017 are not necessarily indicative of the results to be expected for the full fiscal year or any other period. The accompanying consolidated financial statements should be read in conjunction with the financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on February 28, 2017. There have been no significant changes in the Company’s accounting policies from those disclosed in its Annual Report on Form 10-K filed with the SEC on February 28, 2017. Basis of consolidation The consolidated financial statements include the accounts of Inogen, Inc. and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated. Use of estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Management bases these estimates and assumptions upon historical experience, existing and known circumstances, authoritative accounting pronouncements and other factors that management believes to be reasonable. Significant areas requiring the use of management estimates relate to revenue recognition, inventory and rental asset valuations and write-downs, accounts receivable allowances for bad debts, returns and adjustments, stock compensation expense, depreciation and amortization, income tax provision and uncertain tax positions, fair value of financial instruments, and fair value of acquired intangible assets and goodwill. Actual results could differ from these estimates. Business combinations The results of operations of the businesses acquired by the Company are included as of the acquisition date. The purchase price of an acquisition is allocated to the underlying assets acquired and liabilities assumed based upon their estimated fair values at the date of acquisition. To the extent the purchase price exceeds the fair value of the net identifiable tangible and intangible assets acquired and liabilities assumed, such excess is allocated to goodwill. The Company may adjust the preliminary purchase price allocation, as necessary, for up to one year after the acquisition closing date if it obtains more information regarding asset valuations and liabilities assumed. Acquisition-related expenses are recognized separately from the business combination and are expensed as incurred. Goodwill and other acquired intangibles Goodwill is tested for impairment on an annual basis as of October 1. Interim testing of goodwill for impairment is also required whenever an event occurs or circumstances change that would more likely than not reduce the fair value of a reporting unit or asset below its carrying amount. Intangible assets with definite lives are amortized over their estimated useful lives on a straight-line basis. Foreign currency The functional currency of the Company’s international subsidiaries is the local currency. The financial statements of the subsidiaries are translated to U.S. dollars using month-end exchange rates for assets and liabilities, and average rates of exchange for revenues, cost of revenue, operating expense and provision for income taxes. Translation gains and losses are recorded in accumulated other comprehensive income (loss) as a component of stockholders’ equity. Foreign exchange transaction gains and losses resulting from the conversion of the transaction currency to functional currency are reflected as a component of foreign currency exchange gains or losses in other income (expense) in the consolidated statements of comprehensive income. Recently issued accounting pronouncements not yet adopted In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers Revenue with Contracts with Customers: Principal versus Agent Considerations (Reporting Revenue Gross versus Net) In January 2017, the FASB issued ASU No. 2017-01, Clarifying the Definition of a Business In January 2017, the FASB issued ASU No. 2017-04, Simplifying the Test for Goodwill Impairment In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging Recently adopted accounting pronouncements In July 2015, the FASB issued ASU No. 2015-11, Simplifying the Measurement of Inventory In March 2016, the FASB issued ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting , which requires any adjustments to be recorded as of the beginning of fiscal 2016 Business segments The Company operates and reports in only one operating and reportable segment – development, manufacturing, marketing, sales, and rental of respiratory products. Management reports financial information on an aggregate basis to the Company’s chief operating decision maker.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	3. Fair value of financial instruments The Company’s financial instruments consist of cash and cash equivalents, marketable securities, accounts receivable, accounts payable and accrued expenses. The carrying values of its financial instruments approximate fair value based on their short-term nature. Imputed interest associated with the Company’s non-interest bearing debt was insignificant and was appropriately recognized in the respective periods. Fair value accounting Accounting Standards Codification (ASC) 820 — Fair Value Measurements and Disclosures Level input Input definition Level 1 Inputs are unadjusted, quoted prices for identical assets or liabilities in active markets at the measurement date. Level 2 Inputs, other than quoted prices included in Level 1 that are observable for the asset or liability through corroboration with market data at the measurement date. Level 3 Unobservable inputs that reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. The Company obtained the fair value of its available-for-sale investments, which are not in active markets, from a third-party professional pricing service using quoted market prices for identical or comparable instruments, rather than direct observations of quoted prices in active markets. The Company's professional pricing service gathers observable inputs for all of its fixed income securities from a variety of industry data providers (e.g., large custodial institutions) and other third-party sources. Once the observable inputs are gathered, all data points are considered and the fair value is determined. The Company validates the quoted market prices provided by its primary pricing service by comparing their assessment of the fair values against the fair values provided by its investment managers. The Company's investment managers use similar techniques to its professional pricing service to derive pricing as described above. As all significant inputs were observable, derived from observable information in the marketplace or supported by observable levels at which transactions are executed in the marketplace, the Company has classified its available-for-sale investments within Level 2 of the fair value hierarchy. The following table summarizes fair value measurements by level for the assets measured at fair value on a recurring basis for cash, cash equivalents and marketable securities: As of September 30, 2017 Gross Cash Adjusted unrealized and cash Marketable cost losses Fair value equivalents securities Cash $ 50,670 $ — $ 50,670 $ 50,670 $ — Level 1: Money market accounts 77,020 — 77,020 77,020 — Level 2: Certificates of deposit 14,302 (3 ) 14,299 — 14,299 Corporate bonds 18,110 (14 ) 18,096 — 18,096 Agency mortgage-backed securities 3,004 (1 ) 3,003 2,003 1,000 Total $ 163,106 $ (18 ) $ 163,088 $ 129,693 $ 33,395 As of December 31, 2016 Gross Cash Adjusted unrealized and cash Marketable cost losses Fair value equivalents securities Cash $ 48,533 $ — $ 48,533 $ 48,533 $ — Level 1: Money market accounts 39,277 — 39,277 39,277 — Level 2: Certificates of deposit 15,904 (8 ) 15,896 5,041 10,855 Corporate bonds 10,200 (22 ) 10,178 — 10,178 Agency mortgage-backed securities — — — — — Total $ 113,914 $ (30 ) $ 113,884 $ 92,851 $ 21,033 The following table summarizes the estimated fair value of the Company’s investments in marketable securities, accounted for as available-for-sale securities and classified by the contractual maturity date of the securities: September 30, 2017 Due within one year $ 33,395 Derivative instruments and hedging activities The Company transacts business in foreign currencies and has international sales and expenses denominated in foreign currencies, subjecting the Company to foreign currency risk. The Company has entered into foreign currency forward contracts, generally with maturities of twelve months or less, to reduce the volatility of cash flows primarily related to forecasted revenue denominated in certain foreign currencies. These contracts allow the Company to sell Euros in exchange for U.S. dollars at specified contract rates. Forward contracts are used to hedge forecasted sales over specific months. Changes in the fair value of these forward contracts designed as cash flow hedges are recorded as a component of accumulated other comprehensive income (loss) within the consolidated statements of stockholders’ equity and are recognized in the consolidated statements of comprehensive income during the period which approximates the time the corresponding sales occur. The Company may also enter into foreign exchange contracts that are not designated as hedging instruments for financial accounting purposes. These contracts are generally entered into to offset the gains and losses on certain asset and liability balances until the expected time of repayment. Accordingly, any gains or losses resulting from changes in the fair value of the non-designated contracts are reported in other income (expense), net in the consolidated statements of comprehensive income. The gains and losses on these contracts generally offset the gains and losses associated with the underlying foreign currency-denominated balances, which are also reported in other income (expense), net. The Company records the assets or liabilities associated with each derivative instrument and hedging activity at fair value based on Level 2 inputs in other current assets or other current liabilities, respectively, net in the balance sheet. The Company had a payable of $350 as of September 30, 2017 and a receivable of $15 as of December 31, 2016, respectively. The Company classifies the foreign currency derivative instruments within Level 2 in the fair value hierarchy as the valuation inputs are based on quoted prices and market observable data of similar instruments. The accounting for gains and losses resulting from changes in fair value depends on the use of the derivative and whether it is designated and qualifies for hedge accounting. The Company documents the hedging relationship and its risk management objective and strategy for undertaking the hedge, the hedging instrument, the hedged transaction, the nature of the risk being hedged, how the hedging instrument’s effectiveness in offsetting the hedged risk will be assessed prospectively and retrospectively, and a description of the method used to measure ineffectiveness. The Company assesses hedge effectiveness and ineffectiveness at a minimum quarterly but may assess it monthly. For derivative instruments that are designed and qualify as part of a cash flow hedging relationship, the effective portion of the gain or loss on the derivative is reported in other comprehensive income (loss) and reclassified into earnings in the same period or periods during which the hedged transaction affects earnings. Gains and losses on the derivative representing either hedge ineffectiveness or hedge components excluded from the assessment of effectiveness are recognized in current period earnings. The Company will discontinue hedge accounting prospectively when it determines that the derivative is no longer effective in offsetting cash flows attributable to the hedge risk. The cash flow hedge is de-designated when a forecasted transaction is not probable of occurring, or management determines to remove the designation of the cash flow hedge. In all situations in which hedge accounting is discontinued and the derivative remains outstanding, the Company continues to carry the derivative at its fair value on the balance sheet and recognizes any subsequent changes in the fair value in earnings. When it is probable that a forecasted transaction will not occur, the Company will discontinue hedge accounting and recognize immediately in earnings gains and losses that were accumulated in other comprehensive income (loss) related to the hedging relationship. Accumulated other comprehensive income (loss) The components of accumulated other comprehensive income (loss) were as follows: Foreign Unrealized Unrealized Accumulated currency gains (losses) gains (losses) other translation on available-for- on cash comprehensive adjustments sale investments flow hedges income (loss) Balance as of December 31, 2016 $ — $ (82 ) $ 47 $ (35 ) Other comprehensive gain (loss) 312 71 (145 ) 238 Balance as of September 30, 2017 $ 312 $ (11 ) $ (98 ) $ 203

Balance Sheet Components

Balance Sheet Components	9 Months Ended
	Sep. 30, 2017
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	4. Balance sheet components Cash, cash equivalents and marketable securities The Company considers all short-term, highly liquid investments with a maturity of three months or less to be cash equivalents. Cash equivalents are recorded at cost plus accrued interest, which is considered adjusted cost, and approximates fair value. Certificates of deposit and agency mortgage-backed securities are included in cash equivalents and marketable securities based on the maturity date of the security. Short-term investments are included in marketable securities in the current period presentation. The Company considers investments with maturities greater than three months to be marketable securities. Investments are classified as available-for-sale and are reported at fair value with unrealized gains or losses, if any, reported, net of tax, in accumulated other comprehensive income (loss). All income generated and realized gains or losses from investments are recorded to other income (expense), net on the consolidated statements of comprehensive income. The Company reviews its investments to identify and evaluate investments for indication of possible impairment. Factors considered in determining whether a loss is temporary include the length of time and extent to which fair value has been less than the cost basis, the financial condition and near-term prospects of the investee, and the Company's intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in market value. Credit losses and other-than-temporary impairments are declines in fair value that are not expected to recover and are charged to other income (expense), net in the consolidated statements of comprehensive income During the three and nine months ended September 30, 2017 and 2016, respectively, no losses were recognized for other-than-temporary impairments. September 30, December 31, Cash and cash equivalents 2017 2016 Cash $ 50,670 $ 48,533 Money market accounts 77,020 39,277 Certificates of deposit — 5,041 Agency mortgage-backed securities 2,003 — Total cash and cash equivalents $ 129,693 $ 92,851 Marketable securities Certificates of deposit $ 14,299 $ 10,855 Corporate bonds 18,096 10,178 Agency mortgage-backed securities 1,000 — Total marketable securities $ 33,395 $ 21,033 Accounts receivable and allowance for bad debts, returns, and adjustments Accounts receivable are customer obligations due under normal sales and rental terms. The Company performs credit evaluations of the customers’ financial condition and generally does not require collateral. The allowance for doubtful accounts is maintained at a level that, in management’s opinion, is adequate to absorb potential losses related to accounts receivable and is based upon the Company’s continuous evaluation of the collectability of outstanding balances. Management’s evaluation takes into consideration such factors as past bad debt experience, economic conditions and information about specific receivables. The Company’s evaluation also considers the age and composition of the outstanding amounts in determining their net realizable value. The allowance for doubtful accounts is based on estimates, and ultimate losses may vary from current estimates. As adjustments to these estimates become necessary, they are reported in earnings in the periods in which they become known. This allowance is increased by bad debt provisions charged to bad debt expense, net of recoveries, in operating expense and is reduced by direct write-offs. The Company generally does not allow returns from providers for reasons not covered under its standard warranty. Therefore, provision for sales returns applies primarily to direct-to-consumer sales. This reserve is calculated based on actual historical return rates under the Company’s 30-day return program and is applied to the related sales revenue for the last month of the quarter reported. The Company also records an allowance for rental revenue adjustments, which is recorded as a reduction of rental revenue and net rental accounts receivable balances. These adjustments result from contractual adjustments, including untimely claims filings, or billings not paid due to another provider performing same or similar functions for the patient in the same period, all of which prevent billed revenue from becoming realizable. The allowance is based on historical revenue adjustments as a percentage of rental revenue billed and unbilled during the related period. When recording the allowance for doubtful accounts, the bad debt expense account (general and administrative expense account) is charged; when recording allowance for sales returns, the sales returns account (contra sales revenue account) is charged; and when recording the allowance for rental reserve adjustments, the rental revenue adjustments account (contra rental revenue account) is charged. As of September 30, 2017 and December 31, 2016, included in accounts receivable on the consolidated balance sheets were earned but unbilled receivables of $3,117 and $7,484, respectively. These balances reflect gross unbilled rental receivables prior to any allowances for adjustments and write-offs. The Company consistently applies its allowance estimation methodology from period-to-period. The Company’s best estimate is made on an accrual basis and adjusted in future periods as required. Any adjustments to the prior period estimates are included in the current period. As additional information becomes known, the Company adjusts its assumptions accordingly to change its estimate of the allowance. Gross accounts receivable balance concentrations by major category as of September 30, 2017 and December 31, 2016 were as follows: September 30, December 31, Gross accounts receivable 2017 2016 Medicare $ 4,168 $ 12,500 Medicaid/other government 400 617 Private insurance 2,034 3,475 Patient responsibility 2,781 3,227 Business-to-business & other receivables (1) 29,651 19,541 Total gross accounts receivable $ 39,034 $ 39,360 Net accounts receivable (gross accounts receivable, net of allowances) balance concentrations by major category as of September 30, 2017 and December 31, 2016 were as follows: September 30, December 31, Net accounts receivable 2017 2016 Medicare $ 2,877 $ 7,208 Medicaid/other government 280 410 Private insurance 1,545 1,832 Patient responsibility 1,351 2,538 Business-to-business & other receivables (1) 28,646 18,840 Total net accounts receivable $ 34,699 $ 30,828 (1) Business-to-business receivables included one customer with an accounts receivable balance of $11,790 and $9,791 as of September 30, 2017 and December 31, 2016, respectively. This customer received extended payment terms through a direct financing plan offered. The Company also has a credit insurance policy in place, which allocates up to $12,000 in coverage as of September 30, 2017 and allocated up to $9,000 in coverage as of December 31, 2016 for this customer with a $1,000 deductible and 10% retention. The following tables set forth the accounts receivable allowances as of September 30, 2017 and December 31, 2016: September 30, December 31, Allowances - accounts receivable 2017 2016 Doubtful accounts $ 1,920 $ 1,869 Rental revenue adjustments 1,593 6,078 Sales returns 822 585 Total allowances - accounts receivable $ 4,335 $ 8,532 Concentration of credit risk Financial instruments that potentially subject the Company to concentration of credit risk consist principally of cash, cash equivalents, marketable securities and accounts receivable. At times, cash account balances may be in excess of the amounts insured by the Federal Deposit Insurance Corporation (FDIC). However, management believes the risk of loss to be minimal. The Company performs periodic evaluations of the relative credit standing of these institutions and has not experienced any losses on its cash and cash equivalents to date. The Company has entered into hedging relationships with a single counterparty to offset a portion of the forecasted Euro based revenues. The credit risk has been reduced due to a net settlement arrangement whereby the Company is allowed to net settle transactions with a single net amount payable by one party to the other. Concentration of customers and vendors The Company primarily sells its products to traditional home medical equipment providers, distributors, and resellers in the United States and in foreign countries on a credit basis. The Company also sells its products direct to consumers on a primarily prepayment basis. One single customer represented more than 10% of the Company’s total revenue for the nine months ended September 30, 2017, and no single customer represented more than 10% of the Company’s total revenue for the nine months ended September 30, 2016. Two customers with accounts receivable balances of $11,790 and $4,960, respectively, represented more than 10% of the Company’s net accounts receivable balance as of September 30, 2017, and one single customer with an accounts receivable balance of $9,791, represented more than 10% of the Company’s net accounts receivable balance as of December 31, 2016. The Company also rents products directly to consumers for insurance reimbursement, which resulted in a customer concentration relating to Medicare’s service reimbursement programs. Medicare’s service reimbursement programs accounted for 70.1% and 71.0% of rental revenue for the three months ended September 30, 2017 and September 30, 2016, respectively, and based on total revenue was 6.0% and 9.5% for the three months ended September 30, 2017 and September 30, 2016, respectively. Medicare’s service reimbursement programs accounted for 72.8% and 71.6% of rental revenue for the nine months ended September 30, 2017 and September 30, 2016, respectively, and based on total revenue was 7.3% and 12.4% for the nine months ended September 30, 2017 and September 30, 2016, respectively. Net accounts receivable balances relating to Medicare’s service reimbursement programs (including held and unbilled, net of allowances) amounted to $2,877 or 8.3% of total net accounts receivable as of September 30, 2017 as compared to $7,208, or 23.4% of total net accounts receivable as of December 31, 2016. The Company currently purchases raw materials from a limited number of vendors, which resulted in a concentration of three major vendors. The three major vendors supply the Company with raw materials used to manufacture the Company’s products. For the nine months ended September 30, 2017, the Company’s three major vendors accounted for 19.9%, 13.9%, and 9.7%, respectively, of total raw material purchases. For the nine months ended September 30, 2016, the Company’s three major vendors accounted for 22.0%, 14.9% and 7.9%, respectively, of total raw material purchases. A portion of revenue is earned from sales outside the United States. Approximately 77.2% and 72.8% of the non-U.S. revenue for the three months ended September 30, 2017 and September 30, 2016, respectively, were invoiced in Euros. Approximately 75.2% and 70.7% of the non-U.S. revenue for the nine months ended September 30, 2017 and September 30, 2016, respectively, were invoiced in Euros. A breakdown of the Company’s revenue from U.S. and non-U.S. sources for the three months and nine months ended September 30, 2017 and September 30, 2016 is as follows: Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 U.S. revenue $ 51,844 $ 39,470 $ 142,123 $ 113,963 Non-U.S. revenue 17,186 14,952 43,528 38,015 Total revenue $ 69,030 $ 54,422 $ 185,651 $ 151,978 Inventories Inventories are stated at the lower of cost and net realizable value. Cost is determined using a standard cost method, including material, labor and manufacturing overhead, whereby the standard costs are updated at least quarterly to reflect approximate actual costs using the first-in, first-out (FIFO) method. The Company records adjustments at least quarterly to inventory for potentially excess, obsolete, slow-moving or impaired items. The Company recorded noncurrent inventories related to inventories that are expected to be realized or consumed after one year of $391 and $314 as of September 30, 2017 and December 31, 2016, respectively. Noncurrent inventories are primarily related to raw materials purchased to support long-term expected repairs in bulk-purchases to reduce costs and are classified in other assets. Inventories that are considered current consist of the following: September 30, December 31, 2017 2016 Raw materials and work-in-progress $ 13,945 $ 12,382 Finished goods 3,209 2,152 Less: reserves (299 ) (191 ) Inventories $ 16,855 $ 14,343 Property and equipment Property and equipment are stated at cost. Depreciation and amortization are calculated using the straight-line method over the assets’ estimated useful lives as follows: Rental equipment 1.5-5 years Manufacturing equipment and tooling 2-5 years Computer equipment and software 2-3 years Furniture and equipment 3-5 years Leasehold improvements Lesser of estimated useful life or remaining lease term Expenditures for additions, improvements and replacements are capitalized and depreciated or amortized to a salvage value of $0. Repair and maintenance costs on rental equipment are included in cost of rental revenue on the consolidated statements of comprehensive income. Repair and maintenance expense, which includes labor, parts and freight, for rental equipment was $463 and $497 for the three months ended September 30, 2017 and September 30, 2016, respectively, and $1,808 and $1,930 for the nine months ended September 30, 2017 and September 30, 2016, respectively. Included within property and equipment is construction in process, primarily related to the design and engineering of tooling, jigs and other machinery. In addition, this item also includes computer software or development costs that have been purchased, but have not completed the final configuration process for implementation into the Company’s systems. These items have not been placed in service; therefore, no depreciation or amortization was recognized for these items in the respective periods. Depreciation and amortization expense related to property and equipment and rental equipment are summarized below for the three and nine months ended September 30, 2017 and September 30, 2016, respectively. Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Rental equipment $ 2,366 $ 2,878 $ 7,577 $ 8,733 Other property and equipment 469 510 1,427 1,484 Total depreciation and amortization $ 2,835 $ 3,388 $ 9,004 $ 10,217 Property and equipment and rental equipment with associated accumulated depreciation are summarized below for September 30, 2017 and December 31, 2016, respectively. September 30, December 31, Property and equipment 2017 2016 Rental equipment, net of allowances of $808 and $725, respectively $ 51,010 $ 54,582 Other property and equipment 14,729 12,633 Property and equipment 65,739 67,215 Accumulated depreciation Rental equipment 35,323 33,937 Other property and equipment 9,465 8,079 Accumulated depreciation 44,788 42,016 Property and equipment, net Rental equipment, net of allowances of $808 and $725, respectively 15,687 20,645 Other property and equipment 5,264 4,554 Property and equipment, net $ 20,951 $ 25,199 Long-lived assets The Company accounts for the impairment and disposition of long-lived assets in accordance with ASC 360 — Property, Plant, and Equipment Goodwill The changes in the carrying amount of goodwill for the nine months ended September 30, 2017 were as follows: Balance as of December 31, 2016 $ — Acquisition 2,154 Translation adjustment 176 Balance as of September 30, 2017 $ 2,330 Intangible assets There were no impairments recorded related to the Company’s intangible assets during the three months or nine months ended September 30, 2017 and September 30, 2016. Amortization expense for intangible assets for the three months ended September 30, 2017 and September 30, 2016 was $101 and $28, respectively, and for the nine months ended September 30, 2017 and September 30, 2016 was $253 and $73, respectively. The following tables represent the net carrying values of intangible assets as of the respective dates: Average estimated Gross useful lives carrying Accumulated September 30, 2017 (in years) amount amortization Net amount Licenses 10 $ 185 $ 132 $ 53 Patents and websites 5 873 832 41 Customer relationships 4 1,417 147 1,270 Non-compete agreement 3 236 33 203 Commercials 2-3 303 220 83 Total $ 3,014 $ 1,364 $ 1,650 Average estimated Gross useful lives carrying Accumulated December 31, 2016 (in years) amount amortization Net amount Licenses 10 $ 185 $ 118 $ 67 Patents and websites 5 873 810 63 Commercials 2-3 287 176 111 Total $ 1,345 $ 1,104 $ 241 Annual estimated amortization expense for intangibles for each of the succeeding fiscal years is summarized as follows: September 30, 2017 Remaining 3 months of 2017 $ 133 2018 526 2019 472 2020 390 2021 125 Thereafter 4 $ 1,650 Accounts payable and accrued expenses Accounts payable and accrued expenses as of September 30, 2017 and December 31, 2016 consisted of the following: September 30, December 31, 2017 2016 Accounts payable $ 11,033 $ 5,738 Accrued inventory (in-transit and unvouchered receipts) and trade payables 6,999 4,290 Accrued purchasing card liability 2,610 1,760 Accrued franchise, sales and use taxes 582 281 Other accrued expenses 1,143 726 Accounts payable and accrued expenses $ 22,367 $ 12,795

Earnings per Share

Earnings per Share	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Earnings per Share	5. Earnings per share Earnings per share (EPS) is computed in accordance with ASC 260 —Earnings per Share Basic earnings per share is calculated using the Company’s weighted-average outstanding common shares. Diluted earnings per share is calculated using the Company’s weighted-average outstanding common shares including the dilutive effect of stock awards as determined under the treasury stock method. The computation of EPS is as follows: Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Numerator—basic and diluted: Net income $ 7,338 $ 5,246 $ 21,608 $ 15,259 Denominator: Weighted-average common shares - basic common stock (1) 20,753,789 20,157,688 20,622,848 19,986,544 Weighted-average common shares - diluted common stock 21,998,660 21,182,587 21,832,544 21,000,945 Net income per share - basic common stock $ 0.35 $ 0.26 $ 1.05 $ 0.76 Net income per share - diluted common stock $ 0.33 $ 0.25 $ 0.99 $ 0.73 Denominator calculation from basic to diluted: Weighted-average common shares - basic common stock (1) 20,753,789 20,157,688 20,622,848 19,986,544 Stock options and other dilutive awards 1,244,871 1,024,899 1,209,696 1,014,401 Weighted-average common shares - diluted common stock 21,998,660 21,182,587 21,832,544 21,000,945 Shares excluded from diluted weighted-average shares: Stock options 64,498 761,916 64,498 1,357,794 Restricted stock units and restricted stock awards 90,083 — 95,783 — Shares excluded from diluted weighted-average shares 154,581 761,916 160,281 1,357,794 (1) Unvested restricted stock units and restricted stock awards are not included as shares outstanding in the calculation of basic earnings per share. Vested restricted stock units and restricted stock awards are included in basic earnings per share if all vesting and performance criteria have been met. Performance-based restricted stock units and restricted stock awards are included in the number of shares used to calculate diluted earnings per share as long as all applicable performance criteria are met, and their effect is dilutive. Restricted stock awards are eligible to receive all dividends declared on the Company’s common shares during the vesting period; however, such dividends are not paid until the restrictions lapse. The computations of diluted net income attributable to common stockholders excluded common stock options, restricted stock units and restricted stock awards which were anti-dilutive for the three months and nine months ended September 30, 2017 and September 30, 2016, respectively.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	6. Income taxes The Company accounts for income taxes in accordance with ASC 740 —Income Taxes The Company accounts for uncertainties in income tax in accordance with ASC 740-10 —Accounting for Uncertainty in Income Taxes The Company recognizes interest and penalties on taxes, if any, within its income tax provision on its consolidated statements of comprehensive income. No significant interest or penalties were recognized during the periods presented. The Company operates in multiple states domestically and as a result of the acquisition of MedSupport, the Company now has operations in the Netherlands. The statute of limitations has expired for all tax years prior to 2012 for federal jurisdictions and the Netherlands, and 2011 to 2012 for various state tax jurisdictions. However, the net operating loss generated on the Company’s federal and state tax returns in prior years may be subject to adjustments by the federal and state tax authorities. The Company determined the income tax provision for interim periods using an estimate of the Company’s annual effective tax rate, adjusted for discrete items arising in that quarter. In each quarter, the Company updates its estimated annual effective tax rate, and if the estimated annual effective

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Stockholders' Equity	7. Stockholders’ equity The Company has a 2002 Stock Incentive Plan (2002 Plan) as amended, under which the Company granted options to purchase shares of its common stock. As of September 30, 2017, options to purchase 87,711 shares of common stock remained outstanding under the 2002 Plan. The 2002 Plan was terminated in March 2012 in connection with the adoption of the 2012 Plan, and, accordingly, no new options are available for issuance under this plan. The 2002 Plan continues to govern outstanding awards granted thereunder. The Company has a 2012 Equity Incentive Plan (2012 Plan) under which the Company granted options to purchase shares of its common stock. As of September 30, 2017, options to purchase 348,132 shares of common stock remained outstanding under the 2012 Plan. The 2012 Plan was terminated in connection with the Company’s initial public offering in February 2014, and accordingly, no new options are available for issuance under this plan. The 2012 Plan continues to govern outstanding awards granted thereunder. The Company has a 2014 Equity Incentive Plan (2014 Plan) that provides for the grant of incentive stock options, within the meaning of Section 422 of the Internal Revenue Code, to the Company’s employees and any parent and subsidiary corporation’s employees, and for the grant of nonstatutory stock options, restricted stock, restricted stock units, restricted stock awards, stock appreciation rights, performance units and performance shares to its employees, directors and consultants and its parent and subsidiary corporations’ employees and consultants. As of September 30, 2017, awards with respect to 1,621,020 shares of the Company’s common stock were outstanding, and 1,152,589 shares of common stock remained available for issuance under the 2014 Plan. The shares available for issuance under the 2014 Plan will be increased by any shares returned to the 2002 Plan, 2012 Plan and the 2014 Plan as a result of expiration or termination of awards (provided that the maximum number of shares that may be added to the 2014 Plan pursuant to such previously granted awards under the 2002 Plan and 2012 Plan is 2,328,569 shares). The number of shares available for issuance under the 2014 Plan also is increased annually on the first day of each fiscal year by an amount equal to the least of: • 895,346 shares; • 4% of the outstanding shares of common stock as of the last day of the Company’s immediately preceding fiscal year; or • such other amount as the Company’s board of directors may determine. For 2017, an additional 815,594 shares were added to the 2014 Plan share reserve pursuant to the provision described above. Stock options Options typically expire between seven and ten years from the date of grant and vest over one to four-year terms. Options have been granted to employees, directors and consultants of the Company, as determined by the board of directors, at the deemed fair market value of the shares underlying the options at the date of grant. The activity for stock options under the Company’s stock plans is as follows: Remaining weighted- Weighted- average Per share average contractual average Price per exercise terms intrinsic Options share price (in years) value Outstanding as of December 31, 2016 2,355,527 $0.60-$58.95 $ 28.22 5.42 $ 38.95 Granted 64,498 83.30 83.30 Exercised (395,739 ) 0.60-56.72 23.48 Forfeited (63,173 ) 24.52-58.95 43.74 Expired (33 ) 8.70 8.70 Outstanding as of September 30, 2017 1,961,080 0.60-83.30 30.49 4.83 64.61 Vested and exercisable as of September 30, 2017 1,166,512 0.60-83.30 22.89 4.63 72.21 Vested and expected to vest as of September 30, 2017 1,907,844 $0.60-$83.30 $ 30.20 4.82 $ 64.90 The unrecognized compensation expense related to non-vested stock-based compensation granted under the Plans as of September 30, 2017 and September 30, 2016 was $11,401 and $17,607, respectively. S tock incentive awards The Company grants restricted stock units (RSUs) and restricted stock awards (RSAs) under the 2014 Plan (Stock Awards). The Stock Awards vest either based solely on the satisfaction of time-based service conditions or on the satisfaction of time-based service conditions combined with performance criteria. Stock Awards are subject to forfeiture if the holder’s services to the Company terminate before vesting. Stock Awards granted with only time based service vesting conditions generally vest over a four-year service period, as defined in the terms of each award. Stock Awards that vest based on the satisfaction of time based service conditions combined with performance criteria generally vest over a three-year service and performance period, based on performance criteria established at the time of the award. The portion of the Stock Award that is earned may equal or be less than the targeted number of shares subject to the Stock Award depending on whether the performance criteria are met. Restricted stock activity for the nine months ended September 30, 2017, is summarized below: Weighted- average grant Performance and date fair value Time-based time-based Total per share Unvested restricted stock units as of December 31, 2016 — — — $ — Granted 41,100 13,109 54,209 89.64 Vested — — — — Forfeited/canceled — — — — Unvested restricted stock units as of September 30, 2017 41,100 13,109 54,209 $ 89.64 Unvested restricted stock awards outstanding as of December 31, 2016 — — — $ — Granted 20,789 20,785 41,574 91.52 Vested — — — — Forfeited/canceled — — — — Unvested restricted stock awards outstanding as of September 30, 2017 20,789 20,785 41,574 $ 91.52 Unvested and expected to vest restricted stock awards outstanding as of September 30, 2017 17,024 17,027 34,051 $ 91.52 As of September 30, 2017, the unrecognized compensation cost related to unvested employee restricted stock units and restricted stock awards was $6,938, excluding estimated forfeitures. This amount is expected to be recognized over a weighted-average period of 3.1 years. Employee stock purchase plan The Company’s 2014 Employee Stock Purchase Plan (ESPP) provides for the grant to all eligible employees an option to purchase stock under the ESPP, within the meaning Section 423 of the Internal Revenue Code. The ESPP permits participants to purchase common stock through payroll deductions of up to 15% of their eligible compensation, which includes a participant’s base straight time gross earnings, incentive compensation, bonuses, overtime and shift premium, but exclusive of payments for equity compensation and other similar compensation. A participant may purchase a maximum of 1,500 shares during a purchase period. Amounts deducted and accumulated by the participant are used to purchase shares of the Company’s common stock at the end of each six-month period. The purchase price of the shares will be 85% of the lower of the fair market value of the Company’s common stock on the first trading day of each offering period or on the exercise date. The offering periods are currently approximately six months in length beginning on the first business day on or after March 1 and September 1 of each year and ending on the first business day on or after September 1 and March 1 approximately six months later. As of September 30, 2017, a total of 581,106 shares of common stock were available for sale pursuant to the ESPP. The number of shares available for sale under the ESPP is increased annually on the first day of each fiscal year by an amount equal to the least of: • 179,069 shares; • 1.5% of the outstanding shares of the Company’s common stock on the last day of the Company’s immediately preceding fiscal year; or • such other amount as may be determined by the administrator. For 2017, an additional 179,069 shares were added to the ESPP share reserve pursuant to the provision described above. Stock-based compensation Stock-based compensation expense recognized for the three months and nine months ended September 30, 2017 and September 30, 2016 was as follows: Three months ended Nine months ended September 30, September 30, 2017 2016 2017 2016 Stock-based compensation expense by type of award: Stock option plan awards $ 2,012 $ 1,858 $ 5,811 $ 5,063 Restricted stock units and restricted stock awards 402 — 450 — Employee stock purchase plan 109 95 369 341 Total stock-based compensation expense $ 2,523 $ 1,953 $ 6,630 $ 5,404 Employee stock-based compensation expense was calculated based on awards of stock options, restricted stock units and restricted stock awards ultimately expected to vest based on the Company’s historical award cancellations. The employee stock-based compensation expense recognized for the nine months ended September 30, 2017 and September 30, 2016 has been reduced for estimated forfeitures of stock option plan awards at a rate of 7.3% and 7.3%, respectively. The employee stock-based compensation expense recognized for the nine months ended September 30, 2017 has been reduced for estimated forfeitures of restricted stock at a rate of 6.00%. There were no grants of restricted stock units and restricted stock awards for the nine months ended September 30, 2016. ASC 718 – Compensation-Stock Compensation For the three months and nine months ended September 30, 2017 and September 30, 2016, stock-based compensation expense recognized under ASC 718, included in cost of revenues, sales and marketing expense, general and administrative expense, and research and development expense was as follows: Three months ended Nine months ended September 30, September 30, 2017 2016 2017 2016 Cost of revenue $ 205 $ 175 $ 608 $ 454 Research and development 260 223 733 561 Sales and marketing 407 318 1,069 859 General and administrative 1,651 1,237 4,220 3,530 Total stock-based compensation expense $ 2,523 $ 1,953 $ 6,630 $ 5,404 401(k) retirement savings plan The Company maintains a 401(k) retirement savings plan for the benefit of eligible employees. Under the terms of this plan, eligible employees are able to make contributions to the plan on a tax-deferred basis. The Company began matching employees’ contributions, effective January 1, 2017. The Company contributed $430, net of forfeitures, to the 401(k) plan for the nine months ended September 30, 2017. The Company made no contributions to the 401(k) plan for the nine months ended September 30, 2016.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2017
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	8. Commitments and contingencies Leases and non-cancelable contractual obligations The Company leases its facilities and certain equipment under operating leases that expire through September 2024. As of September 30, 2017, the minimum aggregate payments due under operating leases and specified non-cancelable contractual obligations, which consist of software license and maintenance agreements, are summarized as follows: Operating leases Related party leases Non-cancelable contractual obligations Total Remaining 3 months of 2017 $ 309 $ 8 $ 144 $ 461 2018 1,315 32 578 1,925 2019 1,419 32 578 2,029 2020 1,031 10 578 1,619 2021 532 — 456 988 Thereafter 800 — — 800 $ 5,406 $ 82 $ 2,334 $ 7,822 As a result of the MedSupport acquisition, the Company leases a property owned by a related party. Rent expense for the property was $8 and $13 for the three and nine months ended September 30, 2017, respectively. Rent expense of $289 and $263 for the three months ended September 30, 2017 and September 30, 2016, respectively, and $829 and $766 for the nine months ended September 30, 2017 and September 30, 2016, respectively, was included in the accompanying consolidated statements of comprehensive income. Purchase obligations The Company had approximately $36,800 of outstanding purchase orders with its outside vendors and suppliers as of September 30, 2017. Warranty obligations The following table identifies the changes in the Company’s aggregate product warranty liabilities for the nine and twelve-month periods ended September 30, 2017 and December 31, 2016, respectively: September 30, December 31, 2017 2016 Product warranty liability at beginning of period $ 3,480 $ 1,973 Accruals for warranties issued 3,811 3,123 Adjustments related to preexisting warranties (including changes in estimates) 200 118 Settlements made (in cash or in kind) (1,924 ) (1,734 ) Product warranty liability at end of period $ 5,567 $ 3,480 Legislation and HIPAA The healthcare industry is subject to numerous laws and regulations of federal, state and local governments. These laws and regulations include, but are not necessarily limited to, matters such as licensure, accreditation, government healthcare program participation requirements, reimbursement for patient services, and Medicare and Medicaid fraud and abuse. Government activity has continued with respect to investigations and allegations concerning possible violations of fraud and abuse statutes and regulations by healthcare providers. Violations of these laws and regulations could result in exclusion from government healthcare programs together with the imposition of significant fines and penalties, as well as significant repayments for patient services previously billed. The Company believes that it is in compliance in all material respects with applicable fraud and abuse regulations and other applicable government laws and regulations. Compliance with such laws and regulations can be subject to future government review and interpretation as well as regulatory actions unknown or unasserted at this time. The Health Insurance Portability and Accountability Act of 1996 (HIPAA) ensures health insurance portability, reduces healthcare fraud and abuse, guarantees security and privacy of health information, and enforces standards for health information. The Health Information Technology for Economic and Clinical Health Act (HITECH Act) imposes notification requirements of certain security breaches relating to protected health information. The Company may be subject to significant fines and penalties if found not to be compliant with the provisions outlined in the regulations. The Company believes that it complies in all material respects with the provisions of those regulations that are applicable to the Company’s business. Legal proceedings Separation Design Group lawsuit On October 23, 2015, Separation Design Group IP Holdings, LLC (SDGIP) filed a lawsuit against the Company in the United States District Court for the Central District of California. On December 7, 2015, SDGIP filed a First Amended Complaint in the SDGIP Lawsuit. SDGIP alleged that the Company willfully infringed U.S. Patent Nos. 8,894,751 (‘751 Patent) and 9,199,055 (‘055 Patent), both of which are titled “Ultra Rapid Cycle Portable Oxygen Concentrator.” SDGIP also alleged misappropriation of trade secrets and breach of contract stemming from a meeting in September 2010. The Company never received any communication from SDGIP related to patent infringement, misuse of trade secrets, or breach of the mutual non-disclosure agreement prior to SDGIP filing the lawsuit. SDGIP sought to recover damages (including compensatory and treble damages), costs and expenses (including attorneys’ fees), pre-judgment and post-judgment interest, and other relief that the Court deems proper. SDGIP also sought a permanent injunction against the Company. The Company answered SDGIP’s First Amended Complaint, denying SDGIP’s allegations of patent infringement, trade secret misappropriation, and breach of contract and asserting several affirmative defenses. The Company also filed counterclaims against SDGIP alleging that the patents-in-suit were unenforceable due to inequitable conduct. On May 19, 2017, the Patent Trial and Appeal Board (PTAB) of the U.S. Patent and Trademark Office granted the Company’s inter partes The parties reached a mutually agreeable settlement in October 2017. On October 19, 2017, the Court dismissed the lawsuit without prejudice. The parties filed a Joint Stipulation of Dismissal of all claims in the lawsuit with prejudice on November 1, 2017. The Company recognized a loss of $600 for all alleged past damages relating to the asserted patents and trade secrets during the three months ended September 30, 2017 classified within general and administrative expense and the related payable was recorded in accounts payable and accrued expenses as of September 30, 2017. In addition, the Company will record an intangible for future rights to use the patents-in-suit as well as any future patents related to the patents-in-suit of $2,400 in the fourth quarter of 2017. The Company paid $3,000 on November 3, 2017 finalizing the payment of this settlement. Although the Company came to a settlement agreement to remove the risk of uncertain legal and financial obligations going forward, the Company in no way assumed or admitted any wrong doing. CAIRE Inc. lawsuit On September 12, 2016, CAIRE Inc. (CAIRE) filed a lawsuit in the United States District Court for the Northern District of Georgia against the Company. CAIRE alleges that the Company infringes U.S. Patent No. 6,949,133, entitled “Portable Oxygen Concentrator.” CAIRE alleges willful infringement and seeks damages, injunctive relief, pre-judgment and post-judgment interest, costs, and attorneys’ fees. The Company denies CAIRE’s allegations and plans to vigorously contest CAIRE’s claims. On September 11, 2017, the Company filed with the Patent Trial and Appeal Board (PTAB) of the U.S. Patent and Trademark Office a petition for inter partes Other legal proceedings The Company is party to various legal proceedings arising in the normal course of business. The Company carries insurance, subject to specified deductibles under the policies, to protect against losses from certain types of legal claims. At this time, the Company does not anticipate that any of these other proceedings will have a material adverse effect on the Company’s business. Regardless of the outcome, litigation can have an adverse impact on the Company because of defense and settlement costs, diversion of management resources, and other factors.

Foreign Currency Exchange Contr

Foreign Currency Exchange Contracts and Hedging	9 Months Ended
	Sep. 30, 2017
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Foreign currency exchange contracts and hedging	9. Foreign currency exchange contracts and hedging As of September 30, 2017 and September 30, 2016, the Company’s total non-designated and designated derivative contracts had notional amounts totaling approximately $2,251 and $11,117, respectively, and $736 and $2,839, respectively. These contracts were comprised of offsetting contracts with the same counterparty, each expires within one to six months, and had an unrealized loss of approximately $145, net of tax, during the nine months ended September 30, 2017, and an unrealized gain of approximately $27, net of tax, during the nine months ended September 30, 2016. The nonperformance risk of the Company and the counterparty did not have a material impact on the fair value of the derivatives. During the nine months ended September 30, 2017 and September 30, 2016, the ineffective portion relating to these hedges was immaterial and the hedges remained effective through their respective settlement dates. As of September 30, 2017, the Company had fifteen designated hedges and three non-designated hedges. As of September 30, 2016, the Company had fourteen designated hedges and four non-designated hedges.

Basis of Presentation and Sum17

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Basis of Consolidation	Basis of consolidation The consolidated financial statements include the accounts of Inogen, Inc. and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated.
Use of estimates	Use of estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Management bases these estimates and assumptions upon historical experience, existing and known circumstances, authoritative accounting pronouncements and other factors that management believes to be reasonable. Significant areas requiring the use of management estimates relate to revenue recognition, inventory and rental asset valuations and write-downs, accounts receivable allowances for bad debts, returns and adjustments, stock compensation expense, depreciation and amortization, income tax provision and uncertain tax positions, fair value of financial instruments, and fair value of acquired intangible assets and goodwill. Actual results could differ from these estimates.
Business Combinations	Business combinations The results of operations of the businesses acquired by the Company are included as of the acquisition date. The purchase price of an acquisition is allocated to the underlying assets acquired and liabilities assumed based upon their estimated fair values at the date of acquisition. To the extent the purchase price exceeds the fair value of the net identifiable tangible and intangible assets acquired and liabilities assumed, such excess is allocated to goodwill. The Company may adjust the preliminary purchase price allocation, as necessary, for up to one year after the acquisition closing date if it obtains more information regarding asset valuations and liabilities assumed. Acquisition-related expenses are recognized separately from the business combination and are expensed as incurred.
Goodwill and Other Acquired Intangibles	Goodwill and other acquired intangibles Goodwill is tested for impairment on an annual basis as of October 1. Interim testing of goodwill for impairment is also required whenever an event occurs or circumstances change that would more likely than not reduce the fair value of a reporting unit or asset below its carrying amount. Intangible assets with definite lives are amortized over their estimated useful lives on a straight-line basis.
Foreign Currency	Foreign currency The functional currency of the Company’s international subsidiaries is the local currency. The financial statements of the subsidiaries are translated to U.S. dollars using month-end exchange rates for assets and liabilities, and average rates of exchange for revenues, cost of revenue, operating expense and provision for income taxes. Translation gains and losses are recorded in accumulated other comprehensive income (loss) as a component of stockholders’ equity. Foreign exchange transaction gains and losses resulting from the conversion of the transaction currency to functional currency are reflected as a component of foreign currency exchange gains or losses in other income (expense) in the consolidated statements of comprehensive income.
Recently Issued Accounting Pronouncements Not Yet Adopted	Recently issued accounting pronouncements not yet adopted In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers Revenue with Contracts with Customers: Principal versus Agent Considerations (Reporting Revenue Gross versus Net) In January 2017, the FASB issued ASU No. 2017-01, Clarifying the Definition of a Business In January 2017, the FASB issued ASU No. 2017-04, Simplifying the Test for Goodwill Impairment In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging
Recently Adopted Accounting Pronouncements	Recently adopted accounting pronouncements In July 2015, the FASB issued ASU No. 2015-11, Simplifying the Measurement of Inventory In March 2016, the FASB issued ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting , which requires any adjustments to be recorded as of the beginning of fiscal 2016
Business Segments	Business segments The Company operates and reports in only one operating and reportable segment – development, manufacturing, marketing, sales, and rental of respiratory products. Management reports financial information on an aggregate basis to the Company’s chief operating decision maker.

Fair Value of Financial Instr18

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Summary of Fair Value Assets Measured on Recurring Basis for Cash, Cash Equivalents and Marketable Securities	The following table summarizes fair value measurements by level for the assets measured at fair value on a recurring basis for cash, cash equivalents and marketable securities: As of September 30, 2017 Gross Cash Adjusted unrealized and cash Marketable cost losses Fair value equivalents securities Cash $ 50,670 $ — $ 50,670 $ 50,670 $ — Level 1: Money market accounts 77,020 — 77,020 77,020 — Level 2: Certificates of deposit 14,302 (3 ) 14,299 — 14,299 Corporate bonds 18,110 (14 ) 18,096 — 18,096 Agency mortgage-backed securities 3,004 (1 ) 3,003 2,003 1,000 Total $ 163,106 $ (18 ) $ 163,088 $ 129,693 $ 33,395 As of December 31, 2016 Gross Cash Adjusted unrealized and cash Marketable cost losses Fair value equivalents securities Cash $ 48,533 $ — $ 48,533 $ 48,533 $ — Level 1: Money market accounts 39,277 — 39,277 39,277 — Level 2: Certificates of deposit 15,904 (8 ) 15,896 5,041 10,855 Corporate bonds 10,200 (22 ) 10,178 — 10,178 Agency mortgage-backed securities — — — — — Total $ 113,914 $ (30 ) $ 113,884 $ 92,851 $ 21,033
Summary of Estimated Fair Value of Company's Investments in Marketable Debt Securities, Accounted for as Available-for-Sale Securities	The following table summarizes the estimated fair value of the Company’s investments in marketable securities, accounted for as available-for-sale securities and classified by the contractual maturity date of the securities: September 30, 2017 Due within one year $ 33,395
Summary of Components of Accumulated Other Comprehensive Income (Loss)	The components of accumulated other comprehensive income (loss) were as follows: Foreign Unrealized Unrealized Accumulated currency gains (losses) gains (losses) other translation on available-for- on cash comprehensive adjustments sale investments flow hedges income (loss) Balance as of December 31, 2016 $ — $ (82 ) $ 47 $ (35 ) Other comprehensive gain (loss) 312 71 (145 ) 238 Balance as of September 30, 2017 $ 312 $ (11 ) $ (98 ) $ 203

Balance Sheet Components (Table

Balance Sheet Components (Tables)	9 Months Ended
	Sep. 30, 2017
Balance Sheet Related Disclosures [Abstract]
Summary of Cash, Cash Equivalents and Short-term Investments	Cash, cash equivalents and marketable securities consist of the following: September 30, December 31, Cash and cash equivalents 2017 2016 Cash $ 50,670 $ 48,533 Money market accounts 77,020 39,277 Certificates of deposit — 5,041 Agency mortgage-backed securities 2,003 — Total cash and cash equivalents $ 129,693 $ 92,851 Marketable securities Certificates of deposit $ 14,299 $ 10,855 Corporate bonds 18,096 10,178 Agency mortgage-backed securities 1,000 — Total marketable securities $ 33,395 $ 21,033
Schedule of Gross Accounts Receivable Balance Concentrations by Major Category	Gross accounts receivable balance concentrations by major category as of September 30, 2017 and December 31, 2016 were as follows: September 30, December 31, Gross accounts receivable 2017 2016 Medicare $ 4,168 $ 12,500 Medicaid/other government 400 617 Private insurance 2,034 3,475 Patient responsibility 2,781 3,227 Business-to-business & other receivables (1) 29,651 19,541 Total gross accounts receivable $ 39,034 $ 39,360 1. Business-to-business receivables included one customer with an accounts receivable balance of $11,790 and $9,791 as of September 30, 2017 and December 31, 2016, respectively. This customer received extended payment terms through a direct financing plan offered. The Company also has a credit insurance policy in place, which allocates up to $12,000 in coverage as of September 30, 2017 and allocated up to $9,000 in coverage as of December 31, 2016 for this customer with a $1,000 deductible and 10% retention.
Schedule of Net Accounts Receivable Balance Concentrations by Major Category	Net accounts receivable (gross accounts receivable, net of allowances) balance concentrations by major category as of September 30, 2017 and December 31, 2016 were as follows: September 30, December 31, Net accounts receivable 2017 2016 Medicare $ 2,877 $ 7,208 Medicaid/other government 280 410 Private insurance 1,545 1,832 Patient responsibility 1,351 2,538 Business-to-business & other receivables (1) 28,646 18,840 Total net accounts receivable $ 34,699 $ 30,828 (1) Business-to-business receivables included one customer with an accounts receivable balance of $11,790 and $9,791 as of September 30, 2017 and December 31, 2016, respectively. This customer received extended payment terms through a direct financing plan offered. The Company also has a credit insurance policy in place, which allocates up to $12,000 in coverage as of September 30, 2017 and allocated up to $9,000 in coverage as of December 31, 2016 for this customer with a $1,000 deductible and 10% retention.
Schedule of Allowances for Accounts Receivable	The following tables set forth the accounts receivable allowances as of September 30, 2017 and December 31, 2016: September 30, December 31, Allowances - accounts receivable 2017 2016 Doubtful accounts $ 1,920 $ 1,869 Rental revenue adjustments 1,593 6,078 Sales returns 822 585 Total allowances - accounts receivable $ 4,335 $ 8,532
Breakdown of Company's Revenue from U.S. and Non-U.S. Sources	A portion of revenue is earned from sales outside the United States. Approximately 77.2% and 72.8% of the non-U.S. revenue for the three months ended September 30, 2017 and September 30, 2016, respectively, were invoiced in Euros. Approximately 75.2% and 70.7% of the non-U.S. revenue for the nine months ended September 30, 2017 and September 30, 2016, respectively, were invoiced in Euros. A breakdown of the Company’s revenue from U.S. and non-U.S. sources for the three months and nine months ended September 30, 2017 and September 30, 2016 is as follows: Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 U.S. revenue $ 51,844 $ 39,470 $ 142,123 $ 113,963 Non-U.S. revenue 17,186 14,952 43,528 38,015 Total revenue $ 69,030 $ 54,422 $ 185,651 $ 151,978
Schedule of Inventories	Inventories that are considered current consist of the following: September 30, December 31, 2017 2016 Raw materials and work-in-progress $ 13,945 $ 12,382 Finished goods 3,209 2,152 Less: reserves (299 ) (191 ) Inventories $ 16,855 $ 14,343
Computation of Depreciation and Amortization using Straight Line Method Over Estimated Useful Lives of Assets	Property and equipment are stated at cost. Depreciation and amortization are calculated using the straight-line method over the assets’ estimated useful lives as follows: Rental equipment 1.5-5 years Manufacturing equipment and tooling 2-5 years Computer equipment and software 2-3 years Furniture and equipment 3-5 years Leasehold improvements Lesser of estimated useful life or remaining lease term
Summary of Depreciation and Amortization Expense of Property and Equipment and Rental Equipment	Depreciation and amortization expense related to property and equipment and rental equipment are summarized below for the three and nine months ended September 30, 2017 and September 30, 2016, respectively. Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Rental equipment $ 2,366 $ 2,878 $ 7,577 $ 8,733 Other property and equipment 469 510 1,427 1,484 Total depreciation and amortization $ 2,835 $ 3,388 $ 9,004 $ 10,217
Summary of Property Plant and Equipment and Rental Equipment with Associated Accumulated Depreciation	Property and equipment and rental equipment with associated accumulated depreciation are summarized below for September 30, 2017 and December 31, 2016, respectively. September 30, December 31, Property and equipment 2017 2016 Rental equipment, net of allowances of $808 and $725, respectively $ 51,010 $ 54,582 Other property and equipment 14,729 12,633 Property and equipment 65,739 67,215 Accumulated depreciation Rental equipment 35,323 33,937 Other property and equipment 9,465 8,079 Accumulated depreciation 44,788 42,016 Property and equipment, net Rental equipment, net of allowances of $808 and $725, respectively 15,687 20,645 Other property and equipment 5,264 4,554 Property and equipment, net $ 20,951 $ 25,199
Schedule of Changes in Carrying Amount of Goodwill	The changes in the carrying amount of goodwill for the nine months ended September 30, 2017 were as follows: Balance as of December 31, 2016 $ — Acquisition 2,154 Translation adjustment 176 Balance as of September 30, 2017 $ 2,330
Summary of Intangible Assets	The following tables represent the net carrying values of intangible assets as of the respective dates: Average estimated Gross useful lives carrying Accumulated September 30, 2017 (in years) amount amortization Net amount Licenses 10 $ 185 $ 132 $ 53 Patents and websites 5 873 832 41 Customer relationships 4 1,417 147 1,270 Non-compete agreement 3 236 33 203 Commercials 2-3 303 220 83 Total $ 3,014 $ 1,364 $ 1,650 Average estimated Gross useful lives carrying Accumulated December 31, 2016 (in years) amount amortization Net amount Licenses 10 $ 185 $ 118 $ 67 Patents and websites 5 873 810 63 Commercials 2-3 287 176 111 Total $ 1,345 $ 1,104 $ 241
Schedule of Annual Estimated Amortization Expense for Intangibles	Annual estimated amortization expense for intangibles for each of the succeeding fiscal years is summarized as follows: September 30, 2017 Remaining 3 months of 2017 $ 133 2018 526 2019 472 2020 390 2021 125 Thereafter 4 $ 1,650
Schedule of Accounts Payable and Accrued Expenses	Accounts payable and accrued expenses as of September 30, 2017 and December 31, 2016 consisted of the following: September 30, December 31, 2017 2016 Accounts payable $ 11,033 $ 5,738 Accrued inventory (in-transit and unvouchered receipts) and trade payables 6,999 4,290 Accrued purchasing card liability 2,610 1,760 Accrued franchise, sales and use taxes 582 281 Other accrued expenses 1,143 726 Accounts payable and accrued expenses $ 22,367 $ 12,795

Earnings per Share (Tables)

Earnings per Share (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Computation of Earnings Per Share	The computation of EPS is as follows: Three months ended September 30, Nine months ended September 30, 2017 2016 2017 2016 Numerator—basic and diluted: Net income $ 7,338 $ 5,246 $ 21,608 $ 15,259 Denominator: Weighted-average common shares - basic common stock (1) 20,753,789 20,157,688 20,622,848 19,986,544 Weighted-average common shares - diluted common stock 21,998,660 21,182,587 21,832,544 21,000,945 Net income per share - basic common stock $ 0.35 $ 0.26 $ 1.05 $ 0.76 Net income per share - diluted common stock $ 0.33 $ 0.25 $ 0.99 $ 0.73 Denominator calculation from basic to diluted: Weighted-average common shares - basic common stock (1) 20,753,789 20,157,688 20,622,848 19,986,544 Stock options and other dilutive awards 1,244,871 1,024,899 1,209,696 1,014,401 Weighted-average common shares - diluted common stock 21,998,660 21,182,587 21,832,544 21,000,945 Shares excluded from diluted weighted-average shares: Stock options 64,498 761,916 64,498 1,357,794 Restricted stock units and restricted stock awards 90,083 — 95,783 — Shares excluded from diluted weighted-average shares 154,581 761,916 160,281 1,357,794 (1) Unvested restricted stock units and restricted stock awards are not included as shares outstanding in the calculation of basic earnings per share. Vested restricted stock units and restricted stock awards are included in basic earnings per share if all vesting and performance criteria have been met. Performance-based restricted stock units and restricted stock awards are included in the number of shares used to calculate diluted earnings per share as long as all applicable performance criteria are met, and their effect is dilutive. Restricted stock awards are eligible to receive all dividends declared on the Company’s common shares during the vesting period; however, such dividends are not paid until the restrictions lapse.

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Summary of Stock Options Activity	The activity for stock options under the Company’s stock plans is as follows: Remaining weighted- Weighted- average Per share average contractual average Price per exercise terms intrinsic Options share price (in years) value Outstanding as of December 31, 2016 2,355,527 $0.60-$58.95 $ 28.22 5.42 $ 38.95 Granted 64,498 83.30 83.30 Exercised (395,739 ) 0.60-56.72 23.48 Forfeited (63,173 ) 24.52-58.95 43.74 Expired (33 ) 8.70 8.70 Outstanding as of September 30, 2017 1,961,080 0.60-83.30 30.49 4.83 64.61 Vested and exercisable as of September 30, 2017 1,166,512 0.60-83.30 22.89 4.63 72.21 Vested and expected to vest as of September 30, 2017 1,907,844 $0.60-$83.30 $ 30.20 4.82 $ 64.90
Summary of Restricted Stock Activity	Restricted stock activity for the nine months ended September 30, 2017, is summarized below: Weighted- average grant Performance and date fair value Time-based time-based Total per share Unvested restricted stock units as of December 31, 2016 — — — $ — Granted 41,100 13,109 54,209 89.64 Vested — — — — Forfeited/canceled — — — — Unvested restricted stock units as of September 30, 2017 41,100 13,109 54,209 $ 89.64 Unvested restricted stock awards outstanding as of December 31, 2016 — — — $ — Granted 20,789 20,785 41,574 91.52 Vested — — — — Forfeited/canceled — — — — Unvested restricted stock awards outstanding as of September 30, 2017 20,789 20,785 41,574 $ 91.52 Unvested and expected to vest restricted stock awards outstanding as of September 30, 2017 17,024 17,027 34,051 $ 91.52
Summary of Stock-based Compensation Expense	Stock-based compensation Stock-based compensation expense recognized for the three months and nine months ended September 30, 2017 and September 30, 2016 was as follows: Three months ended Nine months ended September 30, September 30, 2017 2016 2017 2016 Stock-based compensation expense by type of award: Stock option plan awards $ 2,012 $ 1,858 $ 5,811 $ 5,063 Restricted stock units and restricted stock awards 402 — 450 — Employee stock purchase plan 109 95 369 341 Total stock-based compensation expense $ 2,523 $ 1,953 $ 6,630 $ 5,404 For the three months and nine months ended September 30, 2017 and September 30, 2016, stock-based compensation expense recognized under ASC 718, included in cost of revenues, sales and marketing expense, general and administrative expense, and research and development expense was as follows: Three months ended Nine months ended September 30, September 30, 2017 2016 2017 2016 Cost of revenue $ 205 $ 175 $ 608 $ 454 Research and development 260 223 733 561 Sales and marketing 407 318 1,069 859 General and administrative 1,651 1,237 4,220 3,530 Total stock-based compensation expense $ 2,523 $ 1,953 $ 6,630 $ 5,404

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2017
Commitments And Contingencies Disclosure [Abstract]
Minimum Aggregate Payments Due under Operating Leases and Specified Non-Cancelable Contractual Obligations Consist of Software License and Maintenance Agreements	The Company leases its facilities and certain equipment under operating leases that expire through September 2024. As of September 30, 2017, the minimum aggregate payments due under operating leases and specified non-cancelable contractual obligations, which consist of software license and maintenance agreements, are summarized as follows: Operating leases Related party leases Non-cancelable contractual obligations Total Remaining 3 months of 2017 $ 309 $ 8 $ 144 $ 461 2018 1,315 32 578 1,925 2019 1,419 32 578 2,029 2020 1,031 10 578 1,619 2021 532 — 456 988 Thereafter 800 — — 800 $ 5,406 $ 82 $ 2,334 $ 7,822
Schedule of Changes in Aggregate Product Warranty Liabilities	The following table identifies the changes in the Company’s aggregate product warranty liabilities for the nine and twelve-month periods ended September 30, 2017 and December 31, 2016, respectively: September 30, December 31, 2017 2016 Product warranty liability at beginning of period $ 3,480 $ 1,973 Accruals for warranties issued 3,811 3,123 Adjustments related to preexisting warranties (including changes in estimates) 200 118 Settlements made (in cash or in kind) (1,924 ) (1,734 ) Product warranty liability at end of period $ 5,567 $ 3,480

Business Overview - Additional

Business Overview - Additional Information (Details) $ in Thousands	May 04, 2017USD ($)	Sep. 30, 2017USD ($)Productlb	Dec. 31, 2017USD ($)
Business Overview Disclosures [Line Items]
Percentage of patients using portable oxygen concentrators		9.10%
Goodwill acquired		$ 2,330
MedSupport Systems B.V.
Business Overview Disclosures [Line Items]
Aggregate payment for acquisition	$ 5,831
Cash paid at closing	5,779
Cash acquired	1,337
Intangible assets acquired	1,529
Goodwill acquired	2,154
Net assets assumed	811
MedSupport Systems B.V. | Scenario Forecast
Business Overview Disclosures [Line Items]
Estimated net working capital adjustments payable			$ 52
MedSupport Systems B.V. | General and Administrative
Business Overview Disclosures [Line Items]
Acquisition expenses	$ 370
Inogen Europe Holding B.V.
Business Overview Disclosures [Line Items]
Date of incorporation of subsidiary		Apr. 13, 2017
One G4
Business Overview Disclosures [Line Items]
Weight of oxygen portable device | lb		2.8
One G3
Business Overview Disclosures [Line Items]
Weight of oxygen portable device | lb		4.8
One G2
Business Overview Disclosures [Line Items]
Weight of oxygen portable device | lb		7
Maximum | One G4
Business Overview Disclosures [Line Items]
Estimated battery life of portable oxygen concentrator		2 hours 36 minutes
Maximum | One G3
Business Overview Disclosures [Line Items]
Estimated battery life of portable oxygen concentrator		4 hours 42 minutes
Maximum | One G2
Business Overview Disclosures [Line Items]
Estimated battery life of portable oxygen concentrator		5 hours
Minimum | Inogen One
Business Overview Disclosures [Line Items]
Number of portable oxygen concentrators | Product		327,000

Basis of Presentation and Sum24

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details)	9 Months Ended
	Sep. 30, 2017Segment
Accounting Policies [Abstract]
Number of operating segments	1
Number of reportable segments	1

Fair Value of Financial Instr25

Fair Value of Financial Instruments - Summary of Fair Value Assets Measured on Recurring Basis for Cash, Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	$ 33,395	$ 21,033
Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Adjusted cost	163,106	113,914
Gross unrealized losses	(18)	(30)
Fair value	163,088	113,884
Cash and cash equivalents	129,693	92,851
Marketable securities	33,395	21,033
Fair Value Measurements Recurring | Cash
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Adjusted cost	50,670	48,533
Fair value	50,670	48,533
Cash and cash equivalents	50,670	48,533
Fair Value Measurements Recurring | Level 1 | Money Market Accounts
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Adjusted cost	77,020	39,277
Fair value	77,020	39,277
Cash and cash equivalents	77,020	39,277
Fair Value Measurements Recurring | Level 2 | Certificates Of Deposit
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Adjusted cost	14,302	15,904
Gross unrealized losses	(3)	(8)
Fair value	14,299	15,896
Cash and cash equivalents		5,041
Marketable securities	14,299	10,855
Fair Value Measurements Recurring | Level 2 | Corporate Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Adjusted cost	18,110	10,200
Gross unrealized losses	(14)	(22)
Fair value	18,096	10,178
Marketable securities	18,096	$ 10,178
Fair Value Measurements Recurring | Level 2 | Agency Mortgage-backed Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Adjusted cost	3,004
Gross unrealized losses	(1)
Fair value	3,003
Cash and cash equivalents	2,003
Marketable securities	$ 1,000

Fair Value of Financial Instr26

Fair Value of Financial Instruments - Summary of Estimated Fair Value of Company's Investments in Marketable Securities, Accounted for as Available-for-Sale Securities (Details) $ in Thousands	Sep. 30, 2017USD ($)
Available For Sale Securities [Abstract]
Due within one year	$ 33,395

Fair Value of Financial Instr27

Fair Value of Financial Instruments - Additional Information (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Accounts receivable, net	$ 34,699	$ 30,828
Forward Contracts
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Payable	$ 350
Accounts receivable, net		$ 15

Fair Value of Financial Instr28

Fair Value of Financial Instruments - Summary of Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance			$ (35)
Other comprehensive gain (loss)	$ 237	$ 8	238	$ 43
Ending Balance	203		203
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income Loss [Line Items]
Other comprehensive gain (loss)			312
Ending Balance	312		312
Unrealized Gains (Losses) on Available-for-sale Investments
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance			(82)
Other comprehensive gain (loss)			71
Ending Balance	(11)		(11)
Unrealized Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance			47
Other comprehensive gain (loss)			(145)
Ending Balance	$ (98)		$ (98)

Balance Sheet Components - Summ

Balance Sheet Components - Summary of Cash, Cash Equivalents and Short-term Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Cash and cash equivalents
Cash	$ 50,670	$ 48,533
Money market accounts	77,020	39,277
Certificates of deposit		5,041
Agency mortgage-backed securities	2,003
Total cash and cash equivalents	129,693	92,851	$ 86,009	$ 66,106
Marketable securities
Marketable securities	33,395	21,033
Certificates Of Deposit
Marketable securities
Marketable securities	14,299	10,855
Corporate Bonds
Marketable securities
Marketable securities	18,096	$ 10,178
Agency Mortgage-backed Securities
Marketable securities
Marketable securities	$ 1,000

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)Customer	Sep. 30, 2016USD ($)Customer	Dec. 31, 2016USD ($)Customer
Schedule Of Balance Sheet Components [Line Items]
Unbilled Receivables	$ 3,117,000		$ 3,117,000		$ 7,484,000
Accounts receivable, net	$ 34,699,000		$ 34,699,000		30,828,000
Percentage of Non-US revenue invoiced in Euros	77.20%	72.80%	75.20%	70.70%
Noncurrent inventories expected to be realized or consumed	$ 391,000		$ 391,000		314,000
Salvage value of expenditures for additions, improvements and replacements	0		0
Repairs and maintenance expense	463,000	$ 497,000	1,808,000	$ 1,930,000
Depreciation and amortization	2,835,000	3,388,000	9,004,000	10,217,000
Impairments of long-lived assets	0	0	0	0
Impairment of finite lived intangible assets	0	0	0	0
Amortization of intangible assets	101,000	28,000	253,000	73,000
Construction in Process and Computer Software or Development Cost
Schedule Of Balance Sheet Components [Line Items]
Depreciation and amortization	0	$ 0	0	$ 0
Medicare
Schedule Of Balance Sheet Components [Line Items]
Accounts receivable, net	2,877,000		2,877,000		7,208,000
Customer Concentration Risk | Customer One
Schedule Of Balance Sheet Components [Line Items]
Accounts receivable, net	11,790,000		11,790,000		$ 9,791,000
Customer Concentration Risk | Customer Two
Schedule Of Balance Sheet Components [Line Items]
Accounts receivable, net	$ 4,960,000		$ 4,960,000
Sales Revenue, Net | Customer Concentration Risk
Schedule Of Balance Sheet Components [Line Items]
Number of customers | Customer			1	0
Concentration risk, percentage	6.00%	9.50%	7.30%	12.40%
Net Accounts Receivable | Customer Concentration Risk
Schedule Of Balance Sheet Components [Line Items]
Number of customers | Customer			2		1
Concentration risk, percentage			8.30%		23.40%
Sales Revenue, Services, Net | Customer Concentration Risk
Schedule Of Balance Sheet Components [Line Items]
Concentration risk, percentage	70.10%	71.00%	72.80%	71.60%
Raw materials | Supplier Concentration Risk | Vendor one
Schedule Of Balance Sheet Components [Line Items]
Concentration risk, percentage			19.90%	22.00%
Raw materials | Supplier Concentration Risk | Vendor two
Schedule Of Balance Sheet Components [Line Items]
Concentration risk, percentage			13.90%	14.90%
Raw materials | Supplier Concentration Risk | Vendor three
Schedule Of Balance Sheet Components [Line Items]
Concentration risk, percentage			9.70%	7.90%

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Gross Accounts Receivable Balance Concentrations by Major Category (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accounts Notes And Loans Receivable [Line Items]
Gross accounts receivable	$ 39,034	$ 39,360
Medicare
Accounts Notes And Loans Receivable [Line Items]
Gross accounts receivable	4,168	12,500
Medicaid Or Other Government
Accounts Notes And Loans Receivable [Line Items]
Gross accounts receivable	400	617
Private Insurance
Accounts Notes And Loans Receivable [Line Items]
Gross accounts receivable	2,034	3,475
Patient Responsibility
Accounts Notes And Loans Receivable [Line Items]
Gross accounts receivable	2,781	3,227
Business To Business And Other Receivables
Accounts Notes And Loans Receivable [Line Items]
Gross accounts receivable	$ 29,651	$ 19,541

Balance Sheet Components - Sc32

Balance Sheet Components - Schedule of Net Accounts Receivable Balance Concentrations by Major Category (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accounts Notes And Loans Receivable [Line Items]
Accounts receivable, net	$ 34,699	$ 30,828
Medicare
Accounts Notes And Loans Receivable [Line Items]
Accounts receivable, net	2,877	7,208
Medicaid Or Other Government
Accounts Notes And Loans Receivable [Line Items]
Accounts receivable, net	280	410
Private Insurance
Accounts Notes And Loans Receivable [Line Items]
Accounts receivable, net	1,545	1,832
Patient Responsibility
Accounts Notes And Loans Receivable [Line Items]
Accounts receivable, net	1,351	2,538
Business To Business And Other Receivables
Accounts Notes And Loans Receivable [Line Items]
Accounts receivable, net	$ 28,646	$ 18,840

Balance Sheet Components - Sc33

Balance Sheet Components - Schedule of Net Accounts Receivable Balance Concentrations by Major Category (Parenthetical) (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2017USD ($)Customer	Dec. 31, 2016USD ($)Customer
Accounts Notes And Loans Receivable [Line Items]
Accounts receivable, net	$ 34,699,000	$ 30,828,000
Customer Concentration Risk | Business To Business Receivables
Accounts Notes And Loans Receivable [Line Items]
Number of customers | Customer	1	1
Accounts receivable, net	$ 11,790,000	$ 9,791,000
Credit insurance policy, deductible amount	$ 1,000,000
Credit insurance policy, retention percentage	10.00%
Customer Concentration Risk | Business To Business Receivables | Maximum
Accounts Notes And Loans Receivable [Line Items]
Credit insurance policy, coverage limit	$ 12,000,000	$ 9,000,000

Balance Sheet Components - Sc34

Balance Sheet Components - Schedule of Allowances for Accounts Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Allowances - accounts receivable
Doubtful accounts	$ 1,920	$ 1,869
Rental revenue adjustments	1,593	6,078
Sales returns	822	585
Total allowances - accounts receivable	$ 4,335	$ 8,532

Balance Sheet Components - Brea

Balance Sheet Components - Breakdown of the Company Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Concentration Risk [Line Items]
Revenues	$ 69,030	$ 54,422	$ 185,651	$ 151,978
U.S. revenue
Concentration Risk [Line Items]
Revenues	51,844	39,470	142,123	113,963
Non-U.S. revenue
Concentration Risk [Line Items]
Revenues	$ 17,186	$ 14,952	$ 43,528	$ 38,015

Balance Sheet Components - Sc36

Balance Sheet Components - Schedule of Inventories (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Raw materials and work-in-progress	$ 13,945	$ 12,382
Finished goods	3,209	2,152
Less: reserves	(299)	(191)
Inventories	$ 16,855	$ 14,343

Balance Sheet Components - Comp

Balance Sheet Components - Computation of Depreciation and Amortization Using Straight Line Method Over Estimated Useful Lives of Assets (Details)	9 Months Ended
	Sep. 30, 2017
Equipment | Minimum
Property Plant And Equipment [Line Items]
Property Plant And Equipment Useful Life	1 year 6 months
Equipment | Maximum
Property Plant And Equipment [Line Items]
Property Plant And Equipment Useful Life	5 years
Manufacturing equipment and tooling | Minimum
Property Plant And Equipment [Line Items]
Property Plant And Equipment Useful Life	2 years
Manufacturing equipment and tooling | Maximum
Property Plant And Equipment [Line Items]
Property Plant And Equipment Useful Life	5 years
Computer equipment and software | Minimum
Property Plant And Equipment [Line Items]
Property Plant And Equipment Useful Life	2 years
Computer equipment and software | Maximum
Property Plant And Equipment [Line Items]
Property Plant And Equipment Useful Life	3 years
Furniture and equipment | Minimum
Property Plant And Equipment [Line Items]
Property Plant And Equipment Useful Life	3 years
Furniture and equipment | Maximum
Property Plant And Equipment [Line Items]
Property Plant And Equipment Useful Life	5 years
Leasehold improvements
Property Plant And Equipment [Line Items]
Property Plant And Equipment Useful Life	Lesser of estimated useful life or remaining lease term

Balance Sheet Components - Su38

Balance Sheet Components - Summary of Depreciation and Amortization Expense of Property and Equipment and Rental Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Property Plant And Equipment [Line Items]
Depreciation	$ 2,366	$ 2,878	$ 7,577	$ 8,733
Depreciation and amortization	2,835	3,388	9,004	10,217
Equipment
Property Plant And Equipment [Line Items]
Depreciation	2,366	2,878	7,577	8,733
Other property and equipment
Property Plant And Equipment [Line Items]
Depreciation and amortization	$ 469	$ 510	$ 1,427	$ 1,484

Balance Sheet Components - Su39

Balance Sheet Components - Summary of Property Plant and Equipment and Rental Equipment with Associated Accumulated Depreciation (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Property and equipment	$ 65,739	$ 67,215
Accumulated depreciation	44,788	42,016
Property and equipment, net	20,951	25,199
Equipment
Property Plant And Equipment [Line Items]
Property and equipment	51,010	54,582
Accumulated depreciation	35,323	33,937
Property and equipment, net	15,687	20,645
Other property and equipment
Property Plant And Equipment [Line Items]
Property and equipment	14,729	12,633
Accumulated depreciation	9,465	8,079
Property and equipment, net	$ 5,264	$ 4,554

Balance Sheet Components - Su40

Balance Sheet Components - Summary of Property Plant and Equipment and Rental Equipment with Associated Accumulated Depreciation (Parenthetical) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Property Plant And Equipment [Abstract]
Rental equipment, allowance	$ 808	$ 725

Balance Sheet Components - Sc41

Balance Sheet Components - Schedule of Changes in Carrying Amount of Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
Acquisition	$ 2,154
Translation adjustment	176
Balance as of September 30, 2017	$ 2,330

Balance Sheet Components - Su42

Balance Sheet Components - Summary of Intangible Assets (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Finite Lived Intangible Assets [Line Items]
Gross carrying amount	$ 3,014	$ 1,345
Accumulated amortization	1,364	1,104
Net amount	$ 1,650	$ 241
Licenses
Finite Lived Intangible Assets [Line Items]
Average estimated useful lives (in years)	10 years	10 years
Gross carrying amount	$ 185	$ 185
Accumulated amortization	132	118
Net amount	$ 53	$ 67
Patents And Websites
Finite Lived Intangible Assets [Line Items]
Average estimated useful lives (in years)	5 years	5 years
Gross carrying amount	$ 873	$ 873
Accumulated amortization	832	810
Net amount	$ 41	63
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Average estimated useful lives (in years)	4 years
Gross carrying amount	$ 1,417
Accumulated amortization	147
Net amount	$ 1,270
Non-Compete Agreement
Finite Lived Intangible Assets [Line Items]
Average estimated useful lives (in years)	3 years
Gross carrying amount	$ 236
Accumulated amortization	33
Net amount	203
Commercials
Finite Lived Intangible Assets [Line Items]
Gross carrying amount	303	287
Accumulated amortization	220	176
Net amount	$ 83	$ 111
Commercials | Minimum
Finite Lived Intangible Assets [Line Items]
Average estimated useful lives (in years)	2 years	2 years
Commercials | Maximum
Finite Lived Intangible Assets [Line Items]
Average estimated useful lives (in years)	3 years	3 years

Balance Sheet Components - Sc43

Balance Sheet Components - Schedule of Annual Estimated Amortization Expense for Intangibles (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Goodwill And Intangible Assets Disclosure [Abstract]
Remaining 3 months of 2017	$ 133
2,018	526
2,019	472
2,020	390
2,021	125
Thereafter	4
Net amount	$ 1,650	$ 241

Balance Sheet Components - Sc44

Balance Sheet Components - Schedule of Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Payables And Accruals [Abstract]
Accounts payable	$ 11,033	$ 5,738
Accrued inventory (in-transit and unvouchered receipts) and trade payables	6,999	4,290
Accrued purchasing card liability	2,610	1,760
Accrued franchise, sales and use taxes	582	281
Other accrued expenses	1,143	726
Accounts payable and accrued expenses	$ 22,367	$ 12,795

Earnings per Share - Computatio

Earnings per Share - Computation of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator—basic and diluted:
Net income	$ 7,338	$ 5,246	$ 21,608	$ 15,259
Denominator:
Weighted-average common shares - basic common stock	20,753,789	20,157,688	20,622,848	19,986,544
Weighted-average common shares - diluted common stock	21,998,660	21,182,587	21,832,544	21,000,945
Net income per share - basic common stock	$ 0.35	$ 0.26	$ 1.05	$ 0.76
Net income per share - diluted common stock	$ 0.33	$ 0.25	$ 0.99	$ 0.73
Weighted-average number of shares used in calculating net income per share attributable to common stockholders:
Weighted-average common shares - basic common stock	20,753,789	20,157,688	20,622,848	19,986,544
Stock options and other dilutive awards	1,244,871	1,024,899	1,209,696	1,014,401
Weighted-average common shares - diluted common stock	21,998,660	21,182,587	21,832,544	21,000,945
Shares excluded from diluted weighted-average shares:
Shares excluded from diluted weighted-average shares	154,581	761,916	160,281	1,357,794
Stock options
Shares excluded from diluted weighted-average shares:
Shares excluded from diluted weighted-average shares	64,498	761,916	64,498	1,357,794
Restricted stock units and restricted stock awards
Shares excluded from diluted weighted-average shares:
Shares excluded from diluted weighted-average shares	90,083		95,783

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Unrecognized tax benefits, interest or penalties recognized	$ 0	$ 0	$ 0	$ 0

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Class Of Stock [Line Items]
Stock-based compensation, unrecognized expense, nonvested granted awards	$ 11,401,000	$ 17,607,000
401(k) Retirement Savings Plan
Class Of Stock [Line Items]
Defined benefit plan, contributed by employer net of forfeitures	$ 430,000	$ 0
Stock options
Class Of Stock [Line Items]
Rate of reduced stock-based compensation expense for estimated forfeiture	7.30%	7.30%
Time based restricted stock units
Class Of Stock [Line Items]
Vesting period	4 years
Grants of units unvested	41,100
Time based restricted stock awards
Class Of Stock [Line Items]
Vesting period	4 years
Grants of units unvested	20,789
Performance and time based restricted stock awards
Class Of Stock [Line Items]
Vesting period	3 years
Grants of units unvested	20,785
Performance and time based restricted stock units
Class Of Stock [Line Items]
Vesting period	3 years
Grants of units unvested	13,109
Restricted stock units and restricted stock awards
Class Of Stock [Line Items]
Unrecognized compensation cost related to unvested employee excluding estimated forfeitures	$ 6,938,000
Amount expected to recognized over weighted-average period	3 years 1 month 7 days
Rate of reduced stock-based compensation expense for estimated forfeiture	6.00%
Grants of units unvested		0
Maximum | Stock options
Class Of Stock [Line Items]
Stock option period, expiration	10 years
Vesting period	4 years
Minimum | Stock options
Class Of Stock [Line Items]
Stock option period, expiration	7 years
Vesting period	1 year
2002 Plan
Class Of Stock [Line Items]
Stock option shares outstanding	87,711
Number of equity awards available for grant	0
2012 Plan
Class Of Stock [Line Items]
Stock option shares outstanding	348,132
Number of equity awards available for grant	0
2014 Plan
Class Of Stock [Line Items]
Stock option shares outstanding	1,621,020
Number of equity awards available for grant	1,152,589
Terms of shares available for issuance	The number of shares available for issuance under the 2014 Plan also is increased annually on the first day of each fiscal year by an amount equal to the least of: 895,346 shares; 4% of the outstanding shares of common stock as of the last day of the Company’s immediately preceding fiscal year; or such other amount as the Company’s board of directors may determine.
Common stock capital shares reserved for future issuance maximum annual increase	895,346
Percentage on outstanding shares of common stock	4.00%
Number of additional number of shares reserve to provision	815,594
2012 Plan and 2002 Plan | Maximum
Class Of Stock [Line Items]
Stock option shares outstanding	2,328,569
2014 ESPP Plan
Class Of Stock [Line Items]
Number of equity awards available for grant	581,106
Terms of shares available for issuance	The number of shares available for sale under the ESPP is increased annually on the first day of each fiscal year by an amount equal to the least of: 179,069 shares; 1.5% of the outstanding shares of the Company’s common stock on the last day of the Company’s immediately preceding fiscal year; or such other amount as may be determined by the administrator.
Percentage on outstanding shares of common stock	1.50%
Number of additional number of shares reserve to provision	179,069
Maximum percentage of common stock eligible to purchase through payroll deductions for participants	15.00%
Maximum number of shares available for participant to purchase during period	1,500
Purchase price as percentage of stock price on offering period	85.00%
Purchase price as percentage of stock price on exercise date	85.00%
Potential increase of shares available for issuance	179,069

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Stock Options Activity (Details) - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Class Of Stock [Line Items]
Stock Options Outstanding, Beginning balance	2,355,527
Stock Options, Granted	64,498
Stock Options, Exercised	(395,739)
Stock Options, Forfeited	(63,173)
Stock Options, Expired	(33)
Stock Options Outstanding, Ending balance	1,961,080	2,355,527
Stock Options, Vested and exercisable	1,166,512
Stock Options, Vested and expected to vest	1,907,844
Price per share, Granted	$ 83.30
Price per share, Expired	8.70
Outstanding, Weighted-average exercise price, Beginning balance	28.22
Weighted-average exercise price, Granted	83.30
Weighted-average exercise price, Exercised	23.48
Weighted-average exercise price, Forfeited	43.74
Weighted-average exercise price, Expired	8.70
Outstanding, Weighted-average exercise price, Ending balance	30.49	$ 28.22
Weighted-average exercise price, Vested and exercisable	22.89
Weighted-average exercise price, Vested and expected to vest	$ 30.20
Remaining weighted-average contractual term, Outstanding	4 years 9 months 29 days	5 years 5 months 1 day
Remaining weighted-average contractual term, Vested and exercisable	4 years 7 months 17 days
Remaining weighted-average contractual term, Vested and expected to vest	4 years 9 months 26 days
Outstanding, Per share average intrinsic value	$ 64.61	$ 38.95
Per share average intrinsic value, Vested and exercisable	72.21
Per share average intrinsic value, Vested and expected to vest	64.90
Minimum
Class Of Stock [Line Items]
Outstanding, Price per share, Beginning balance	0.60
Price per share, Exercised	0.60
Price per share, Forfeited	24.52
Outstanding, Price per share, Ending balance	0.60	0.60
Price per share, Vested and exercisable	0.60
Price per share, Vested and expected to vest	0.60
Maximum
Class Of Stock [Line Items]
Outstanding, Price per share, Beginning balance	58.95
Price per share, Exercised	56.72
Price per share, Forfeited	58.95
Outstanding, Price per share, Ending balance	83.30	$ 58.95
Price per share, Vested and exercisable	83.30
Price per share, Vested and expected to vest	$ 83.30

Stockholders' Equity - Summar49

Stockholders' Equity - Summary of Restricted Stock Activity (Details)	9 Months Ended
	Sep. 30, 2017$ / sharesshares
Time based restricted stock units
Class Of Stock [Line Items]
Granted	41,100
Unvested restricted stock units/ awards outstanding, Ending balance	41,100
Performance and time based restricted stock units
Class Of Stock [Line Items]
Granted	13,109
Unvested restricted stock units/ awards outstanding, Ending balance	13,109
Restricted stock units
Class Of Stock [Line Items]
Granted	54,209
Unvested restricted stock units/ awards outstanding, Ending balance	54,209
Weighted-average grant date fair value per share, Granted | $ / shares	$ 89.64
Weighted-average grant date fair value per share, Unvested restricted stock units/ awards outstanding, Ending balance | $ / shares	$ 89.64
Time based restricted stock awards
Class Of Stock [Line Items]
Granted	20,789
Unvested restricted stock units/ awards outstanding, Ending balance	20,789
Unvested and expected to vest restricted stock awards outstanding	17,024
Performance and time based restricted stock awards
Class Of Stock [Line Items]
Granted	20,785
Unvested restricted stock units/ awards outstanding, Ending balance	20,785
Unvested and expected to vest restricted stock awards outstanding	17,027
Restricted stock awards
Class Of Stock [Line Items]
Granted	41,574
Unvested restricted stock units/ awards outstanding, Ending balance	41,574
Unvested and expected to vest restricted stock awards outstanding	34,051
Weighted-average grant date fair value per share, Granted | $ / shares	$ 91.52
Weighted-average grant date fair value per share, Unvested restricted stock units/ awards outstanding, Ending balance | $ / shares	91.52
Weighted-average grant date fair value per share, Unvested and expected to vest restricted stock awards outstanding | $ / shares	$ 91.52

Stockholders' Equity - Summar50

Stockholders' Equity - Summary of Stock-based Compensation Expense Recognized (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Stock-based compensation expense by type of award:
Stock-based compensation expense	$ 2,523	$ 1,953	$ 6,630	$ 5,404
Stock Option Plan Awards
Stock-based compensation expense by type of award:
Stock-based compensation expense	2,012	1,858	5,811	5,063
Restricted stock units and restricted stock awards
Stock-based compensation expense by type of award:
Stock-based compensation expense	402		450
Employee Stock Purchase Plan
Stock-based compensation expense by type of award:
Stock-based compensation expense	$ 109	$ 95	$ 369	$ 341

Stockholders' Equity - Summar51

Stockholders' Equity - Summary of Stock-based Compensation Expense Recognized in Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Class Of Stock [Line Items]
Stock-based compensation expense	$ 2,523	$ 1,953	$ 6,630	$ 5,404
Cost of Revenue
Class Of Stock [Line Items]
Stock-based compensation expense	205	175	608	454
Research and Development
Class Of Stock [Line Items]
Stock-based compensation expense	260	223	733	561
Sales and Marketing
Class Of Stock [Line Items]
Stock-based compensation expense	407	318	1,069	859
General and Administrative
Class Of Stock [Line Items]
Stock-based compensation expense	$ 1,651	$ 1,237	$ 4,220	$ 3,530

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	Nov. 03, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016
Commitments And Contingencies [Line Items]
Rent expense		$ 289	$ 263	$ 829	$ 766
Outstanding purchase orders with its outside vendors and suppliers		36,800		36,800
Intangible		1,650		1,650			$ 241
Subsequent Event
Commitments And Contingencies [Line Items]
Amount paid after finalizing the payment of settlement	$ 3,000
Patents | Scenario Forecast
Commitments And Contingencies [Line Items]
Intangible						$ 2,400
General and Administrative
Commitments And Contingencies [Line Items]
Loss from settlement		600
MedSupport Systems B.V.
Commitments And Contingencies [Line Items]
Rent expense		$ 8		$ 13
Offices and Certain Equipment
Commitments And Contingencies [Line Items]
Operating leases expiration date				Sep. 30, 2024

Commitments and Contingencies53

Commitments and Contingencies - Minimum Aggregate Payments Due under Operating Leases and Specified Non-Cancelable Contractual Obligations Consist of Software License and Maintenance Agreements (Details) $ in Thousands	Sep. 30, 2017USD ($)
Commitments And Contingencies Disclosure [Abstract]
Operating leases, Remaining 3 months of 2017	$ 309
Operating leases, 2018	1,315
Operating leases, 2019	1,419
Operating leases, 2020	1,031
Operating leases, 2021	532
Operating leases, Thereafter	800
Operating leases, Total minimum payments	5,406
Related party leases, Remaining 3 months of 2017	8
Related party leases, 2018	32
Related party leases, 2019	32
Related party leases, 2020	10
Related party leases, Total minimum payments	82
Non-cancelable contractual obligations, Remaining 3 months of 2017	144
Non-cancelable contractual obligations, 2018	578
Non-cancelable contractual obligations, 2019	578
Non-cancelable contractual obligations, 2020	578
Non-cancelable contractual obligations, 2021	456
Non-cancelable contractual obligations, Total minimum payments	2,334
Remaining 3 months of 2017	461
2,018	1,925
2,019	2,029
2,020	1,619
2,021	988
Thereafter	800
Total minimum payments	$ 7,822

Commitments and Contingencies54

Commitments and Contingencies - Schedule of Changes in Aggregate Product Warranty Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Product warranty liability at beginning of period	$ 3,480	$ 1,973
Accruals for warranties issued	3,811	3,123
Adjustments related to preexisting warranties (including changes in estimates)	200	118
Settlements made (in cash or in kind)	(1,924)	(1,734)
Product warranty liability at end of period	$ 5,567	$ 3,480

Foreign Currency Exchange Con55

Foreign Currency Exchange Contracts and Hedging - Additional Information (Details)	9 Months Ended
	Sep. 30, 2017USD ($)Contract	Sep. 30, 2016USD ($)Contract
Derivatives Fair Value [Line Items]
Number of contract designated hedges | Contract	15	14
Number of contract non-designated hedges | Contract	3	4
Non-Designated Derivative Contracts
Derivatives Fair Value [Line Items]
Derivative contracts notional amounts	$ 2,251,000	$ 736,000
Designated Derivative Contracts
Derivatives Fair Value [Line Items]
Derivative contracts notional amounts	11,117,000	2,839,000
Unrealized (loss) gain on derivative	$ (145,000)	$ 27,000
Minimum
Derivatives Fair Value [Line Items]
Derivative contracts expiration period	1 month
Maximum
Derivatives Fair Value [Line Items]
Derivative contracts expiration period	6 months