Inogen (INGN) 10-Q 11 Aug 15 2015 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2015	Jul. 31, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
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	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		19,347,033

Balance Sheets

Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents	$ 51,822	$ 56,836
Short-term investments	14,240
Accounts receivable, net of allowances of $6,299 and $3,745 at June 30, 2015 and December 31, 2014, respectively	24,765	19,349
Inventories, net of allowances of $168 and $141 at June 30, 2015 and December 31, 2014,respectively	9,308	7,616
Deferred cost of revenue	460	515
Income tax receivable	2,148	2,129
Deferred tax asset - current	4,976	4,976
Prepaid expenses and other current assets	1,723	1,122
Total current assets	109,442	92,543
Property and equipment
Rental equipment, net of allowances of $932 and $832 at June 30, 2015 and December 31, 2014, respectively	52,597	48,359
Manufacturing equipment and tooling	4,271	3,985
Computer equipment and software	4,155	3,699
Furniture and equipment	778	649
Leasehold improvements	933	756
Land and building	126	126
Construction in process	400	193
Total property and equipment	63,260	57,767
Less accumulated depreciation	(31,086)	(25,840)
Property and equipment, net	32,174	31,927
Intangible assets, net	238	270
Deferred tax asset - noncurrent	15,248	15,248
Other assets	97	97
Total assets	157,199	140,085
Current liabilities
Accounts payable and accrued expenses	17,181	11,273
Accrued payroll	4,257	4,066
Current portion of long-term debt	307	299
Warranty reserve - current	1,065	781
Deferred revenue - current	2,278	2,316
Total current liabilities	25,088	18,735
Long-term liabilities
Warranty reserve - noncurrent	541	334
Deferred revenue - noncurrent	3,155	2,176
Long-term debt, net of current portion	159	315
Other noncurrent liabilities	339	375
Total liabilities	$ 29,282	$ 21,935
Commitments and contingencies (Note 5)
Stockholders' equity
Common stock, $0.001 par value per share; 200,000,000 and 60,000,000 shares authorized; 19,346,143 and 19,059,364 shares issued and outstanding at June 30, 2015 and December 31, 2014, respectively	$ 19	$ 19
Additional paid-in capital	179,560	174,824
Accumulated deficit	(51,662)	(56,693)
Total stockholders' equity	127,917	118,150
Total liabilities and stockholders' equity	$ 157,199	$ 140,085

Balance sheets (Parenthetical)

Balance sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Statement Of Financial Position [Abstract]
Allowances for accounts receivable	$ 6,299	$ 3,745
Allowances for inventories	168	141
Allowances for rental equipment	$ 932	$ 832
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	19,346,143	19,059,364
Common stock, shares outstanding	19,346,143	19,059,364

Statements of Operations

Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenue
Sales revenue	$ 32,385	$ 20,464	$ 55,434	$ 35,321
Rental revenue	11,644	9,929	22,347	18,705
Total revenue	44,029	30,393	77,781	54,026
Cost of revenue
Cost of sales revenue	17,866	10,682	30,455	18,223
Cost of rental revenue, including depreciation of $2,944 and $2,503 for the three months ended and $5,900 and $4,760 for the six months ended, respectively	5,341	4,597	10,481	8,751
Total cost of revenue	23,207	15,279	40,936	26,974
Gross profit
Gross profit-sales revenue	14,519	9,782	24,979	17,098
Gross profit-rental revenue	6,303	5,332	11,866	9,954
Total gross profit	20,822	15,114	36,845	27,052
Operating expense
Research and development	975	879	1,838	1,514
Sales and marketing	7,567	6,364	14,491	12,069
General and administrative	6,935	3,908	12,653	7,957
Total operating expense	15,477	11,151	28,982	21,540
Income from operations	5,345	3,963	7,863	5,512
Other income (expense)
Interest expense	(6)	(203)	(13)	(336)
Interest income	26	12	38	18
Change in fair value of preferred stock warrant liability				36
Other income (expense)	(51)	4	(156)	11
Total other expense, net	(31)	(187)	(131)	(271)
Income before provision for income taxes	5,314	3,776	7,732	5,241
Provision for income taxes	1,855	1,490	2,701	2,067
Net income	$ 3,459	$ 2,286	$ 5,031	$ 3,174
Basic net income per share attributable to common stockholders (Note 2)	$ 0.18	$ 0.13	$ 0.26	$ 0.13
Diluted net income per share attributable to common stockholders (Note 2)	$ 0.17	$ 0.11	$ 0.24	$ 0.11
Weighted-average number of shares used in calculating net income per share attributable to common stockholders:
Basic common shares	19,310,064	18,201,661	19,239,218	13,843,803
Diluted common shares	20,672,414	20,146,915	20,617,342	15,826,754

Statements of Operations (Paren

Statements of Operations (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement [Abstract]
Depreciation	$ 2,944	$ 2,503	$ 5,900	$ 4,760

Statement of Stockholders' Equi

Statement of Stockholders' Equity (Deficit) - 6 months ended Jun. 30, 2015 - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Accumulated deficit
Beginning Balance at Dec. 31, 2014	$ 118,150	$ 19	$ 174,824	$ (56,693)
Beginning Balance, shares at Dec. 31, 2014		19,059,364
Stock-based compensation	1,327		1,327
Employee stock purchase	342		342
Employee stock purchase, shares		18,551
Excess tax benefits from stock-based compensation arrangements	2,688		2,688
Stock options exercised	$ 379		379
Stock options exercised, shares	268,228	268,228
Net income	$ 5,031			5,031
Ending Balance at Jun. 30, 2015	$ 127,917	$ 19	$ 179,560	$ (51,662)
Ending Balance, shares at Jun. 30, 2015		19,346,143

Statements of Cash Flows

Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities
Net income	$ 5,031	$ 3,174
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	6,908	5,586
Loss on rental units and other fixed assets	648	921
Provision for sales returns	1,291	1,178
Provision for doubtful accounts	1,118	571
Provision for rental revenue adjustments	4,286	3,411
Provision for inventory obsolescence	53	79
Provision for other inventory losses	60
Stock-based compensation expense	1,327	666
Decrease in fair value of preferred stock warrant liability		(36)
Deferred tax assets		(284)
Excess tax benefits from stock-based compensation arrangements	(2,688)
Changes in operating assets and liabilities:
Accounts receivable	(12,111)	(10,574)
Inventories	(1,805)	(1,932)
Deferred costs of revenue	55	(142)
Income tax receivable	2,669	87
Prepaid expenses and other current assets	(601)	(595)
Accounts payable and accrued expenses	5,923	3,190
Accrued payroll	191	(57)
Warranty reserve	491	269
Deferred revenue	941	1,267
Income tax payable		1,435
Other noncurrent liabilities	(36)	(54)
Net cash provided by operating activities	13,751	8,160
Cash flows from investing activities
Purchases of available-for-sale investments	(20,557)
Maturities of available-for-sale investments	6,317
Investment in intangible assets	(11)	(180)
Production and purchase of rental equipment	(6,485)	(6,752)
Purchases of property and equipment	(1,275)	(603)
Net cash used in investing activities	(22,011)	(7,535)
Cash flows from financing activities
Proceeds from borrowings		6,000
Proceeds from redeemable convertible preferred stock warrants and common stock warrants exercised		467
Proceeds from stock options exercised	379	109
Proceeds from initial public offering		56,471
Costs associated with initial public offering		(4,911)
Proceeds from employee stock purchase	342
Repayment of debt from investment in intangible assets	(163)	(86)
Repayment of borrowings		(3,150)
Excess tax benefits from stock-based compensation arrangements	2,688
Net cash provided by financing activities	3,246	54,900
Net increase (decrease) in cash and cash equivalents	(5,014)	55,525
Cash and cash equivalents, beginning of period	56,836	13,521
Cash and cash equivalents, end of period	51,822	69,046
Supplemental disclosures of cash flow information
Cash paid during the period for interest	15	317
Cash paid during the period for income taxes, net of refunds received	$ 33	802
Non-cash transactions:
Deemed dividend on redeemable convertible preferred stock		$ 987

General

General	6 Months Ended
	Jun. 30, 2015
Organization Consolidation And Presentation Of Financial Statements [Abstract]
General	1. General a) Basis of presentation The unaudited financial statements have been prepared on the same basis as the annual audited financial statements and, in the opinion of management, reflect all adjustments necessary for a fair presentation for each of the periods presented. The results of operations for interim periods are not necessarily indicative of results to be achieved for full fiscal years or other interim periods. 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 ® ® Although portable oxygen concentrators represent the fastest-growing segment of the Medicare oxygen therapy market, the Company estimates based on 2013 Medicare data that patients using portable oxygen concentrators represent approximately 5% to 7% of the total addressable oxygen market in the United States. Based on 2013 industry data, the Company believes it was the leading worldwide manufacturer of portable oxygen concentrators, as well as the largest provider of portable oxygen concentrators to Medicare patients, as measured by dollar volume. 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, as well as compete with the home medical equipment providers that many rely on 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 its Inogen One systems to more than 97,000 patients as of June 30, 2015. Revenue has grown from $10,700 in 2009 to $112,500 in 2014. As contemplated by the Securities and Exchange Commission (SEC) under Rule 10-01 of Regulation S-X, the accompanying financial statements and related footnotes have been condensed and do not contain certain information that will be included in the Company’s annual financial statements and footnotes thereto. For further information refer to the financial statements and related footnotes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2014 filed with the SEC on April 27, 2015 (Annual Report). b) Use of estimates The preparation of the Company’s financial statements in accordance with generally accepted accounting principles in the United States (GAAP) requires management to make estimates and assumptions that affect the amounts reported in these financial statements and accompanying condensed notes. 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 inventory and rental asset valuations and write-downs, accounts receivable reserves and allowance for bad debts, returns and adjustments, stock compensation expense, impairment assessments, depreciation and amortization, income tax provision and uncertain tax positions, fair value of financial instruments, and fair values of acquired intangibles. Actual results could differ materially from these estimates. c) Reclassifications Certain reclassifications have been made to prior years’ financial statements to conform to current period financial statements’ presentation with no effect on previously reported financial position, results of operations or cash flows. These changes consisted of reclassifications to certain line items in the accompanying Statements of Operations and Statements of Cash Flows. d) Initial public offering (IPO) The Company completed an initial public offering on February 20, 2014, and sold 3,529,411 shares to the public for $16.00 per share. In addition, the selling stockholders sold 981,902 shares for a combined total of 4,511,313 shares sold in the offering. The Company netted approximately $49,668 after the underwriters’ discount and other associated expenses. In connection with the completion of the Company’s IPO, the Company’s 9,546,140 shares of redeemable convertible preferred stock and 66,666 shares of convertible preferred stock were automatically converted into 14,259,647 shares of common stock. Following the IPO, all warrants previously exercisable for preferred stock became exercisable for common stock. The previously reported warrant liability associated with the convertible warrants was applied to additional paid-in capital. During the six months ended June 30, 2014, the Company recognized a partial period deemed dividend of $987 for the time-frame the redeemable convertible preferred stock was outstanding during the period. The Company had no redeemable convertible preferred stock or convertible preferred stock outstanding as of December 31, 2014 or June 30, 2015, respectively. As of June 30, 2015, the Company had 19,346,143 shares of common stock outstanding. e ) Recent Accounting Pronouncements Revenue Recognition: In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update No. 2014-09 (ASU 2014-09), The update supersedes nearly all existing revenue recognition guidance under GAAP. The core principle of ASU 2014-09 is to recognize revenues when promised goods or services are transferred to customers in an amount that reflects the consideration to which an entity expects to be entitled to those goods or services. ASU 2014-09 defines a five step process to achieve this core principle and, in doing so, more judgment and estimates may be required within the revenue recognition process than are required under existing GAAP. Subsequent to June 30, 2015, the FASB decided to delay the effective date of ASU 2014-09 by one year. The FASB also agreed to allow entities to choose to adopt the standard as of the original effective date. As such, the updated standard will be effective for us in the first quarter of 2018, with the option to adopt t in the first quarter of 2017. The Company is currently evaluating the impact of the Company’s pending adoption of ASU 2014-09 on the Company’s financial statements and has not yet determined the method by which the Company will adopt the standard. Interest: In April 2015, the FASB issued ASU 2015-03 , . The update requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. This update is effective for our fiscal year beginning January 1, 2016 with early adoption permitted. The adoption of this standard is not expected to have a material effect on our financial condition, results of operations or cash flows. Intangibles - Goodwill and Other - Internal Use Software: In April 2015, the FASB issued ASU 2015-05 , The update provides guidance on fees paid by an entity in a cloud computing arrangement and whether an arrangement includes a license to the underlying software. If a cloud computing arrangement includes a software license, then the entity should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the entity should account for the arrangement as a service contract. This update is effective for our fiscal year beginning January 1, 2016. The adoption of this standard is not expected to have a material effect on our financial condition, results of operations or cash flows.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2015
Accounting Policies [Abstract]
Summary of significant accounting policies	2. Summary of significant accounting policies Sales revenue The Company generates revenue primarily from sales and rentals of its products. The Company’s products consist of its proprietary line of oxygen concentrators and related accessories. Other revenue, which is included in sales revenue on the Statements of Operations, comes from service contracts, extended warranty contracts and freight revenue for product shipments. Revenue from product sales is recognized when all of the following criteria are met: (1) persuasive evidence of an arrangement exists; (2) delivery has occurred or services have been rendered; (3) the price to the customer is fixed or determinable; and (4) collectability is reasonably assured. Revenue from product sales is generally recognized upon shipment of the product. Provisions for estimated returns and discounts are made at the time revenue is recognized. Provisions for standard warranty obligations, which are included in cost of sales revenue on the Statements of Operations, are also provided for at the time revenue is recognized. Revenue from the sale of the Company’s services is recognized when no significant obligations remain undelivered and collection of the receivables is reasonably assured. The Company offers extended service contracts on its Inogen One concentrator line for periods ranging from 12 to 24 months after the end of the standard warranty period. Revenue from these extended service contracts is recognized in income on a straight-line basis over the contract period. Accruals for estimated standard warranty expenses are made at the time that the associated revenue is recognized. The provisions for estimated returns, discounts and warranty obligations are made based on known claims and discount commitments and estimates of additional returns and warranty obligations based on historical data and future expectations. The Company’s accrued warranty liability was $1,606 and $1,115 for future warranty costs as of June 30, 2015 and December 31, 2014, respectively. The Company also offers a lifetime warranty for direct-to-consumer sales. For a fixed price, the Company agrees to provide a fully functional oxygen concentrator for the remaining life of the patient. Lifetime warranties are only offered to patients upon the initial sale of oxygen equipment by the Company and are non-transferable. Product sales with lifetime warranties are considered to be multiple element arrangements within the scope of the Accounting Standards Codification (ASC) 605-25 —Revenue Recognition-Multiple-Element Arrangements. There are two deliverables when a product that includes a lifetime warranty is sold. The first deliverable is the oxygen concentrator equipment which comes with a standard warranty of three years. The second deliverable is the lifetime warranty that provides for a functional oxygen concentrator for the remaining lifetime of the patient. These two deliverables qualify as separate units of accounting. The revenue is allocated to the two deliverables on a relative selling price method. The Company has vendor-specific objective evidence of selling price for the equipment. To determine the selling price of the lifetime warranty, the Company uses its best estimate of the selling price for that deliverable as the lifetime warranty is neither separately priced nor is the selling price available through third-party evidence. To calculate the selling price associated with the lifetime warranties, management considered the profit margins of the overall business, the average estimated cost of lifetime warranties and the price of extended warranties. A significant estimate used to calculate the price and expense of lifetime warranties is the life expectancy of patients. Based on clinical studies, the Company estimates that 60% of patients will succumb to their disease within three years. Given the approximate mortality rate of 20% per year, the Company estimates on average all patients will succumb to their disease within five years. The Company has taken into consideration that when patients decide to buy an Inogen portable oxygen concentrator with a lifetime warranty, they typically have already been on oxygen for a period of time, which can have a large impact on their life expectancy from the time the Company’s product is deployed. After applying the relative selling price method, revenue from equipment sales is recognized when all other revenue recognition criteria for product sales are met. Lifetime warranty revenue is recognized using the straight-line method during the fourth and fifth year after the delivery of the equipment which is the estimated usage period of the contract based on the average patient life expectancy. Shipping and handling costs for sold products and rental assets shipped to the Company’s customers are included on the Statements of Operations as part of cost of sales revenue and cost of rental revenue, respectively. Revenue from the sales of used rental equipment is recognized upon shipment and when collectability is reasonably assured and other revenue recognition criteria are met. When a rental unit is sold, the related cost and accumulated depreciation are removed from their respective accounts, and any gains or losses are included in cost of sales revenue on the Statements of Operations. Rental revenue The Company recognizes equipment rental revenue over the non-cancelable lease term, which is one month, less estimated adjustments, in accordance with ASC 840— Leases The lease term begins on the date products are shipped to patients and are recorded at amounts estimated to be received under reimbursement arrangements with third-party payors, including Medicare, private payors, and Medicaid. Due to the nature of the industry and the reimbursement environment in which the Company operates, certain estimates are required to record net revenue and accounts receivable at their net realizable values. Inherent in these estimates is the risk that they will have to be revised or updated as additional information becomes available. Specifically, the complexity of many third-party billing arrangements and the uncertainty of reimbursement amounts for certain services from certain payors may result in adjustments to amounts originally recorded. Such adjustments are typically identified and recorded at the point of cash application, claim denial or account review. Accounts receivable are reduced by an allowance for doubtful accounts which provides for those accounts from which payment is not expected to be received although product was delivered and revenue was earned. Upon determination that an account is uncollectible, it is written-off and charged to the allowance. Amounts billed but not earned due to the timing of the billing cycle are deferred and recognized in income on a straight-line basis over the monthly billing period. For example, if the first day of the billing period does not fall on the first of the month, then a portion of the monthly billing period will fall in the subsequent month and the related revenue and cost would be deferred based on the service days in the following month. Rental revenue is recognized as earned, less estimated adjustments. Revenue not billed at the end of the period is reviewed for the likelihood of collections and accrued. The rental revenue stream is not guaranteed and payment will cease if the patient no longer needs oxygen or returns the equipment. Revenue recognized is at full estimated allowable amounts; transfers to secondary insurances or patient responsibility have no net effect on revenue. Rental revenue is earned for that month if the patient is on service on the first day of the 30-day period commencing on the recurring date of service for a particular claim, regardless if there is a change in condition or death after that date. Included in rental revenue are unbilled amounts for which the revenue recognition criteria had been met as of period-end but were not yet billed to the payor. The estimate of unbilled rental revenue is based on historical trends and estimates of future collectability. In addition, the Company estimates potential future adjustments and write-offs of these unbilled amounts and includes these estimates in the allowance for adjustments and write-offs of rental revenue which is netted against gross receivables. Fair value of financial instruments The Company’s financial instruments consist of cash and cash equivalents, short-term investments, accounts receivable, accounts payable and accrued expenses, debt and warrants. The carrying values of cash and cash equivalents, short-term investments, accounts receivable and accounts payable and accrued expenses approximate fair values based on the short-term nature of these financial instruments. The fair value of the Company’s debt approximates carrying value based on the Company’s current incremental borrowing rate for similar types of borrowing arrangements. Imputed interest associated with the Company’s non-interest bearing debt is insignificant and has been appropriately recognized in the respective periods. Fair value accounting 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 securities, 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 securities 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: As of December 31, 2014 Level 1 Level 2 Level 3 Total Certificates of deposit $ — $ 11,633 $ — $ 11,633 Total assets $ — $ 11,633 $ — $ 11,633 As of June 30, 2015 Level 1 Level 2 Level 3 Total Certificates of deposit $ — $ 23,587 $ — $ 23,587 Total assets $ — $ 23,587 $ — $ 23,587 Cash Equivalents The Company considers all short-term highly liquid investments with a maturity of three months or less to be cash equivalents. Cash equivalents primarily consist of funds held in money market accounts, which were $10,100 and $42,300 as of June 30, 2015 and December 31, 2014, respectively. Cash equivalents are recorded at cost plus accrued interest, which approximates fair value. Certificates of deposit are included in cash equivalents and short-term investments based on the maturity date of the security. Investments The Company considers investments with maturities greater than three months, but less than one year, to be short-term investments. Investments that have maturities of more than one year are classified as long-term investments. 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. The fair value measurement of the investments had an immaterial impact on Other Comprehensive Income. The Company does not have any other items which would be classified within Other Comprehensive Income. Therefore, there would be no change between the reported Net Income and Other Comprehensive Income due to the immateriality of the unrealized gains or losses associated with investments. The The Company reviews its investments to identify and evaluate investments that have an 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 interest and other income (expense), net. 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 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 that they become known. The 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, net of recoveries. The Company generally does not allow returns from providers for reasons not covered under its standard warranty. Therefore, provision for sales returns applies to direct-to-consumer sales only. This reserve is calculated based on actual historical return rates under the Company’s 30-day return program and is applied to the sales revenue for direct-to-consumer sales for the last month of the quarter reported. The Company also records an allowance for rental revenue adjustments and write-offs, which is recorded as a reduction of rental revenue and rental accounts receivable balances. These adjustments and write-offs result from contractual adjustments, audit adjustments, 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 reserve is based on historical revenue adjustments as a percentage of rental revenue billed and rental revenue 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 adjustments, the rental revenue adjustments account (contra rental revenue account) is charged. As of June 30, 2015 and December 31, 2014, included in accounts receivable on the balance sheets were earned but unbilled receivables of $4,141 and $3,653, respectively. These balances reflect gross unbilled receivables prior to any allowances for adjustments and write-offs. Concentration of credit risk Financial instruments that potentially subject the Company to concentration of credit risk consist principally of cash and cash equivalents 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. Concentration of customers and vendors The Company sells its products to home medical equipment providers, distributors, and resellers in the United States and in foreign countries on a credit basis. The Company sells its products to consumers on a prepayment basis. No single customer represented more than 10% of the Company’s total revenue for the six months ended June 30, 2015 and June 30, 2014. No single customer represented more than 10% of the Company’s total accounts receivable balance as of June 30, 2015, or as of December 31, 2014. 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 73.1% and 71.7% of rental revenue for the three months ended June 30, 2015 and June 30, 2014, respectively, and based on total revenue were 19.3% and 23.4% for the three months ended June 30, 2015 and June 30, 2014, respectively. Medicare’s service reimbursement programs accounted for 72.9% and 72.1% of rental revenue for the six months ended June 30, 2015 and June 30, 2014, respectively, and based on total revenue were 21.0% and 25.0% for the six months ended June 30, 2015 and June 30, 2014, respectively. Accounts receivable balances relating to Medicare’s service reimbursement programs amounted to $7,488 or 30.2% of total accounts receivable as of June 30, 2015 as compared to $4,875, or 25.2% of total accounts receivable as of December 31, 2014. 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 six months ended June 30, 2015, the Company’s three major vendors accounted for 21.6%, 17.7%, and 9.6%, respectively, of total raw material purchases. For the six months ended June 30, 2014, the Company’s three major vendors accounted for 22.6%, 18.1% and 8.5%, respectively, of total raw material purchases. A portion of revenue is earned from sales outside the United States. Approximately 70% of the non-U.S. revenue for the three months and six months ended June 30, 2015 was invoiced in euros. We did not begin to invoice in euros until the fourth quarter of 2014. A breakdown of the Company’s revenue from U.S. and non-U.S. sources for the three months and six months ended June 30, 2015 and June 30, 2014 is as follows: Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 U.S. revenue $ 33,458 $ 24,237 $ 58,812 $ 43,424 Non-U.S. revenue 10,571 6,156 18,969 10,602 Total revenue $ 44,029 $ 30,393 $ 77,781 $ 54,026 Inventories Inventories are stated at the lower of cost or market. 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 and market represents the lower of replacement cost or estimated net realizable value. The Company records adjustments at least quarterly to inventory for potentially excess, obsolete, slow-moving or impaired items. Inventories consist of the following: June 30, December 31, 2015 2014 Raw materials and work-in-progress $ 8,118 $ 6,774 Finished goods 1,358 983 Less: reserves (168 ) (141 ) Inventories $ 9,308 $ 7,616 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 5 years Computer equipment and software 3 years Furniture and equipment 3-5 years Leasehold improvements Shorter of 3-10 years or life of underlying lease Expenditures for additions, improvements and replacements are capitalized and depreciated to a salvage value of zero. Repair and maintenance costs are included in cost of revenue on the Statements of Operations. Repair and maintenance expense, which includes labor, parts and freight for rental equipment was $642 and $400 for the three months ended June 30, 2015 and June 30, 2014, respectively, and $1,212 and $790 for the six months ended June 30, 2015 and June 30, 2014, respectively. Included within property and equipment is construction in process relating to the design and engineering of tooling, jigs and other machinery. In addition, this item also includes computer software that has been purchased, but has not completed the final configuration process for implementation into the Company’s systems. These items have not been placed in service; therefore, no depreciation and amortization has been recognized in respective periods. Depreciation and amortization expense related to property and equipment and rental equipment is summarized below for the three months ended June 30, 2015 and June 30, 2014, respectively, and for the six months ended June 30, 2015 and June 30, 2014, respectively. Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Rental equipment $ 2,944 $ 2,503 $ 5,900 $ 4,760 Other property and equipment 498 384 965 746 Total depreciation and amortization $ 3,442 $ 2,887 $ 6,865 $ 5,506 Property and equipment and rental equipment with associated accumulated depreciation is summarized below for June 30, 2015 and December 31, 2014, respectively. June 30, December 31, Property and equipment 2015 2014 Rental equipment, net of allowance $ 52,597 $ 48,359 Other property and equipment 10,663 9,408 Property and equipment 63,260 57,767 Accumulated depreciation Rental equipment 25,383 21,084 Other property and equipment 5,703 4,756 Accumulated depreciation 31,086 25,840 Net property and equipment Rental equipment 27,214 27,275 Other property and equipment 4,960 4,652 Property and equipment, net $ 32,174 $ 31,927 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 operations as income tax expense. No significant interest or penalties were recognized during the periods presented. The Company operates in multiple states. The statute of limitations has expired for all tax years prior to 2011 for federal and 2010 to 2011 for various state tax purposes. However, the net operating loss generated on the federal and state tax returns in prior years may be subject to adjustments by the federal and state tax authorities. Income tax expense was $1,855 and $2,701, an effective tax rate of 34.9% and 34.9%, for the three and six months ended June 30, 2015, respectively, compared to $1,490 and $2,067, an effective tax rate of 39.5% and 39.4%, for the comparable periods ended June 30, 2014, respectively. Variations in the tax rate year-over-year were primarily due to a decrease in permanent tax differences related to the domestic production activities deduction and the California research and development tax credit. Accounting for stock-based compensation The Company accounts for its stock-based compensation in accordance with ASC 718, Compensation—Stock Compensation As part of the provisions of ASC 718, the Company is required to estimate potential forfeitures of stock grants and adjust compensation cost recorded accordingly. The estimate of forfeitures will be adjusted over the requisite service period to the extent that actual forfeitures differ, or are expected to differ, from such estimates. Changes in estimated forfeitures will be recognized through a cumulative catch-up adjustment in the period of change and will also impact the amount of stock compensation expense to be recognized in future periods. Business segments The Company operates in only one business segment – manufacturing, sales, rental and marketing of respiratory products. Earnings per share Earnings per share (EPS) is computed in accordance with ASC 260, Earnings per Share The shares used to compute basic and diluted net income per share represent the weighted-average common shares outstanding, reduced by the weighted-average unvested common shares subject to repurchase. The computation of EPS is as follows: Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Numerator—basic: Net income $ 3,459 $ 2,286 $ 5,031 $ 3,174 Less deemed dividend on redeemable convertible preferred stock — — — (987 ) Net income before preferred rights dividend 3,459 2,286 5,031 2,187 Less: undistributed earnings to preferred stock - basic — — — (438 ) Net income attributable to common stockholders - basic $ 3,459 $ 2,286 $ 5,031 $ 1,749 Numerator—diluted: Net income $ 3,459 $ 2,286 $ 5,031 $ 3,174 Less deemed dividend on redeemable convertible preferred stock — — — (987 ) Net income before preferred rights dividend 3,459 2,286 5,031 2,187 Less: undistributed earnings to preferred stock - diluted — — — (393 ) Net income attributable to common stockholders - diluted $ 3,459 $ 2,286 $ 5,031 $ 1,794 Denominator: Weighted-average common shares - basic common stock 19,310,064 18,201,661 19,239,218 13,843,803 Weighted-average common shares - diluted common stock 20,672,414 20,146,915 20,617,342 15,826,754 Net income per share - basic common stock $ 0.18 $ 0.13 $ 0.26 $ 0.13 Net income per share - diluted common stock $ 0.17 $ 0.11 $ 0.24 $ 0.11 Shares excluded from diluted net income: Stock options 582,970 — 612,970 — Shares excluded from diluted net income 582,970 — 612,970 — Denominator calculation from basic to diluted: Weighted-average common shares - basic common stock 19,310,064 18,201,661 19,239,218 13,843,803 Warrants 9,663 159,475 9,657 166,455 Stock options 1,352,687 1,785,779 1,368,467 1,816,496 Weighted-average common shares - diluted common stock 20,672,414 20,146,915 20,617,342 15,826,754 The computations of diluted net income attributable to common stockholders exclude common stock options which were anti-dilutive for the three months and six months ended June 30, 2015.

Intangible Assets

Intangible Assets	6 Months Ended
	Jun. 30, 2015
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible Assets	3. Intangible assets During the year ended December 31, 2008, the Company acquired Comfort Life Medical, LLC. The acquisition resulted in recording an intangible asset in the amount of $92 related to the Medicare license held by the acquired company. The Company amortizes this intangible asset over its estimated useful life of ten years. As of June 30, 2015 and December 31, 2014, there were no impairments recorded related to this intangible asset. On April 1, 2009, Comfort Life Medical, LLC merged with Inogen, Inc., and was simultaneously dissolved. During the year ended December 31, 2009, the Company was assigned four patents previously held as an exclusive license from Air Products & Chemicals (APC) in exchange for an increase in a long-term liability due to APC of $250. The acquisition of these patents resulted in an intangible asset of $250. During the year ended December 31, 2011, the Company purchased additional patents from APC for a total value of $650. The Company amortizes these intangible assets over an estimated useful life of five years. There were no impairments recorded related to these intangible assets during the three months and six months ended June 30, 2015 and June 30, 2014. The Company recalculated interest and amortization during the respective periods based on adjusted asset and debt. During the year ended December 31, 2011, the Company acquired Breathe Oxygen Services, LLC. The acquisition resulted in recording an intangible asset in the amount of $66 related to the Medicare license held by the acquired Breathe Oxygen Services that allowed them to operate in the state of Tennessee as well as other assets. On August 29, 2011, Breathe Oxygen Services, LLC merged with Inogen, Inc., and was simultaneously dissolved. The Company amortizes this intangible asset over its estimated useful life of ten years. During the three months and six months ended June 30, 2015 and June 30, 2014, there were no impairments recorded related to this intangible asset. The Company also capitalizes costs incurred for the production of direct response advertising commercials and amortizes these intangible assets over a useful life of two years. During the six months ended June 30, 2015, the Company paid $11 for its production of commercials. The Company did not capitalize any intangible assets during the three months ended June 30, 2015. During the three months and six months ended June 30, 2014, the Company paid $11 and $180, respectively, for its patient setup video, website development and redesign, and production of commercials. Amortization expense for intangible assets for the three months ended June 30, 2015 and June 30, 2014 was $22 and $41, respectively, and for the six months ended June 30, 2015 and June 30, 2014 was $43 and $80, respectively.

Long-Term Debt

Long-Term Debt	6 Months Ended
	Jun. 30, 2015
Debt Disclosure [Abstract]
Long-Term Debt	4. Long-term debt JP Morgan Chase debt In November 2014, the Company secured a primary banking relationship that provides access to a $15,000 working capital revolving line of credit, and treasury and cash management services through commercial banking with JP Morgan Chase. This agreement is a three year working capital revolving line of credit which replaces the previous loan facility the Company maintained with Comerica. The interest rate on outstanding debt balances will be the London Interbank Offer Rate (LIBOR) plus 1.25%. The Company is required to maintain a tangible net worth not less than $90,000 and EBITDA of $10,000 for any period of four consecutive quarters commencing with the four-quarter test period ending September 30, 2014. Beginning with the second quarter of 2016, the EBITDA will increase to a $12,500 minimum calculation, of which the Company is currently compliant under either requirement as of June 30, 2015, and no debt balances were outstanding on the credit facility. June 30, December 31, 2015 2014 Contractual obligation, bearing imputed interest at prime plus two, quarterly payments of $53 beginning May 2011 through October 2014 and quarterly payments of $81 beginning January 2015 through October 2016 $ 466 $ 614 Less: current maturities (307 ) (299 ) Long-term debt, net of current portion $ 159 $ 315 As of June 30, 2015, the minimum aggregate payments due under non-cancelable debt are summarized as follows: June 30, 2015 Remaining 6 months of 2015 $ 151 2016 315 Total $ 466

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2015
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	5. Commitments and contingencies Leases The Company leases its offices and certain equipment under operating leases that expire through January 2022. As of June 30, 2015, the minimum aggregate payments due under non-cancelable leases are summarized as follows: June 30, 2015 Remaining 6 months of 2015 $ 512 2016 1,041 2017 1,052 2018 1,044 2019 1,057 Thereafter 819 $ 5,525 Rent expense of $220 and $180 for the three months ended June 30, 2015 and June 30, 2014, respectively, and $440 and $387 for the six months ended June 30, 2015 and June 30, 2014, respectively, was included in the accompanying Statements of Operations. Warranty obligation The following table identifies the changes in the Company’s aggregate product warranty liabilities for the six and twelve month periods ended June 30, 2015 and December 31, 2014, respectively: June 30, December 31, 2015 2014 Product warranty liability at beginning of period $ 1,115 $ 809 Accruals for warranties issued 927 1,075 Adjustments related to preexisting warranties (including changes in estimates) 260 406 Settlements made (in cash or in kind) (696 ) (1,175 ) Product warranty liability at end of period $ 1,606 $ 1,115 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 expulsion 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 Company believes that it complies in all material respects with the provisions of those regulations that are applicable to the Company’s business. The Health Insurance Portability and Accountability Act (HIPAA) assures 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. Legal proceedings On November 4, 2011, the Company filed a lawsuit in the United States District Court for the Central District of California against Inova Labs Inc., or Defendant, for infringement of two of the Company’s patents. The case, Inogen Inc. v. Inova Labs Inc., Case No. 8:11-cv-01692-JST-AN, or the Lawsuit, involves U.S. Patent Nos. 7,841,343, entitled “Systems and Methods For Delivering Therapeutic Gas to Patients”, or the ’343 patent, and 6,605,136 entitled “Pressure Swing Adsorption Process Operation And Optimization”, or the ’136 patent. The Company alleged in the Lawsuit that certain of Defendant’s oxygen concentrators infringe various claims of the ’343 and ’136 patents. The Lawsuit seeks damages, injunctive relief, costs and attorney fees. The Defendant has answered the complaint, denying infringement and asserting various sets of defenses including non-infringement, invalidity and unenforceability, patent misuse, unclean hands, laches and estoppel. The Defendant also filed counterclaims against us alleging patent invalidity, non-infringement and inequitable conduct. The Company denied the allegations in the Defendant’s counterclaims. The Company has filed a motion to dismiss Defendant’s inequitable conduct counterclaim. The Defendant filed a request with the U.S. Patent and Trademark Office seeking an inter partes reexamination of the ’343 and ’136 patents. The Defendant also filed a motion to stay the Lawsuit pending outcome of the reexamination. On March 20, 2012, the Court granted the Defendant’s motion to stay the Lawsuit pending outcome of the reexamination and also granted the Company’s motion to dismiss the Defendant’s inequitable conduct counterclaim. Securities class action lawsuit On March 13 and March 19, 2015, plaintiffs Brad Christi and Roger D. Holford each filed, respectively, a lawsuit against Inogen, Raymond Huggenberger, Inogen’s President and Chief Executive Officer, and Alison Bauerlein, Inogen’s Executive Vice President and Chief Financial Officer, in the United States District Court for the Central District of California on behalf of a purported class of purchasers of our securities between November 12, 2014 and March 11, 2015. The complaints alleged that Inogen, Mr. Huggenberger and Ms. Bauerlein violated Section 10(b) of the Securities Exchange Act of 1934, as amended (the Exchange Act), and Rule 10b-5 promulgated thereunder, and that Mr. Huggenberger and Ms. Bauerlein violated Section 20(a) of the Exchange Act. Specifically, the complaints alleged that during the purported class period our financial statements and disclosures concerning internal controls over financial reporting were materially false and misleading. The complaints sought compensatory damages in an unspecified amount, costs and expenses, including attorneys’ fees and expert fees, prejudgment and post-judgment interest and such other relief as the court deemed proper. On May 7, 2015, plaintiff Roger D. Holford filed a notice of voluntary dismissal without prejudice pursuant to Federal Rule of Civil Procedure Rule 41(a)(1)(A) in the second filed action. On June 29, 2015, plaintiff Brad Christi filed a notice of voluntary dismissal without prejudice pursuant to Federal Rule of Civil Procedure Rule 41(a)(1)(A) in the first filed action. The case was closed by the Court as of June 29, 2015. The Company is party to various legal proceedings arising in the normal course of business. The Company carries insurance, subject to deductibles under the specified policies, to protect against losses from certain types of legal claims. The Company does not anticipate that any of these proceedings will have a material impact on the Company.

Stock Incentive Plans

Stock Incentive Plans	6 Months Ended
	Jun. 30, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Incentive Plans	6. Stock incentive plans The Company has a 2012 Stock Incentive Plan (2012 Plan) under which the Company granted options to purchase shares of its common stock. As of June 30, 2015, options to purchase 713,776 shares of common stock remained outstanding under the 2012 Plan. The 2012 Plan was terminated in connection with the Company’s initial public offering, 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 2002 Stock Incentive Plan (2002 Plan) as amended, under which the Company granted options to purchase shares of its common stock. As of June 30, 2015, options to purchase 548,249 shares of common stock remained outstanding under the 2002 Plan. The 2002 Plan 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’s board of directors adopted and its stockholders approved a 2014 Equity Incentive Plan (2014 Plan) effective immediately prior to the effectiveness of its initial public offering. The 2014 Plan 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, 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 June 30, 2015, a total of 1,724,487 shares of common stock have been reserved for issuance pursuant to the 2014 Plan, of which options to purchase 1,304,564 shares of the Company’s common stock were outstanding, and 410,367 shares of common stock remained available for issuance. The shares to be reserved for issuance under the 2014 Plan will include 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 includes an annual increase on the first day of each fiscal year 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 2015, an additional 762,373 shares were added to the 2014 Plan share reserve pursuant to the provision described above. 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 at the deemed fair market value, as determined by the board of directors, 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: Options Price per share Weighted-average exercise price Remaining weighted-average contractual terms (in years) Per share average intrinsic value Outstanding as of December 31, 2014 2,261,633 $0.60-$24.52 $ 7.31 6.43 $ 24.06 Granted 582,970 38.54 38.54 Exercised (268,228 ) 0.60-16.62 1.41 Forfeited (9,786 ) 0.75-16.62 4.46 Expired — — — Outstanding as of June 30, 2015 2,566,589 0.60-38.54 15.03 6.24 29.57 Vested and exercisable as of June 30, 2015 1,112,609 0.60-18.93 4.39 5.59 40.21 Vested and expected to vest as of June 30, 2015 2,438,494 $0.60-$38.54 $ 14.84 6.20 $ 29.76 The Company’s board of directors adopted and its stockholders approved a 2014 Employee Stock Purchase Plan (ESPP) effective immediately prior to the effectiveness of its initial public offering. The 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 June 30, 2015, a total of 309,299 shares of common stock have been reserved for sale pursuant to the ESPP. The number of shares available for sale under the ESPP includes an annual increase on the first day of each fiscal year. · 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 2015, an additional 179,069 shares were added to the ESPP share reserve pursuant to the provision described above. The activity for the ESPP is as follows: First Offering Second Offering Period Period Employee accumulated payroll deductions $ 414 $ 343 Total shares purchased 30,358 18,551 Payroll deductions used to purchase shares $ 413 $ 342 Transfer to next offering period $ 1 $ 1 FMV at enrollment date per share $ 16.00 $ 21.69 FMV at purchase date per share $ 21.69 $ 33.62 Purchase price per share $ 13.60 $ 18.44 Stock-based compensation expense recognized for the three months and six months ended June 30, 2015 for the ESPP was $105 and $190, respectively, and is combined with the 2014 Plan compensation expense for a total compensation expense of $809 and $1,327 for the three months and six months ended June 30, 2015, respectively. The number of equity awards available for grant under the 2014 Plan as of June 30, 2015 and December 31, 2014 was 410,367 and 221,178, respectively. Employee stock-based compensation expense recognized for the six months ended June 30, 2015 and June 30, 2014 was calculated based on awards ultimately expected to vest and has been reduced for estimated forfeitures at a rate of 7.5% and 7.3%, respectively, based on the Company’s historical option cancellations. ASC 718 requires forfeitures to be estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. For the three months ended June 30, 2015 and June 30, 2014, stock-based compensation expense recognized under ASC 718, included in cost of sales, sales and marketing expense, general and administrative expense, and research and development expense, totaled $809 and $535, respectively, and for the six months ended June 30, 2015 and June 30, 2014 was $1,327 and $666, respectively. The unrecognized compensation expense related to non-vested share based compensation granted under the Plans as of June 30, 2015 and June 30, 2014 was $11,830 and $5,438, respectively.

Warrants

Warrants	6 Months Ended
	Jun. 30, 2015
Equity [Abstract]
Warrants	7. Warrants In connection with certain of its previous convertible preferred stock issuances, convertible debt financings, and other financing arrangements, the Company had issued warrants for shares of its common stock. A summary of outstanding common stock warrants as of June 30, 2015 is as follows: Number of Exercise Expiration Security warrants price/share date Common stock 15,218 $ 0.30 2017-2019

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2015
Subsequent Events [Abstract]
Subsequent Events	8. Subsequent Events Resignation of Director On August 3, 2015, Timothy Petersen notified the Company that he has resigned as a member of its board of directors; the Compensation, Nominating, and Governance Committee; and the Audit Committee, effective immediately. Mr. Petersen’s resignation was not the result of any disagreement with the Company relating to the Company’s operations, policies or practices. The board of directors has reduced the size of the Compensation, Nominating, and Governance Committee by one member following the departure of Mr. Petersen. Appointment of Director On August 3, 2015, the Board appointed R. Scott Greer to the Board, effective immediately. Mr. Greer will serve as a Class I director, with a term expiring at the annual meeting of stockholders to be held in 2015. In addition, on the same date, the board of directors appointed Mr. Greer as a member of the Audit Committee, replacing Timothy Petersen. Since June 2003, Mr. Greer has served on numerous public and private boards and has extensive corporate governance experience. Mr. Greer holds a B.A. in economics from Whitman College and an M.B.A. from Harvard University. He also was a certified public accountant.

Summary of Significant Accoun16

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2015
Accounting Policies [Abstract]
Sales Revenue	Sales revenue The Company generates revenue primarily from sales and rentals of its products. The Company’s products consist of its proprietary line of oxygen concentrators and related accessories. Other revenue, which is included in sales revenue on the Statements of Operations, comes from service contracts, extended warranty contracts and freight revenue for product shipments. Revenue from product sales is recognized when all of the following criteria are met: (1) persuasive evidence of an arrangement exists; (2) delivery has occurred or services have been rendered; (3) the price to the customer is fixed or determinable; and (4) collectability is reasonably assured. Revenue from product sales is generally recognized upon shipment of the product. Provisions for estimated returns and discounts are made at the time revenue is recognized. Provisions for standard warranty obligations, which are included in cost of sales revenue on the Statements of Operations, are also provided for at the time revenue is recognized. Revenue from the sale of the Company’s services is recognized when no significant obligations remain undelivered and collection of the receivables is reasonably assured. The Company offers extended service contracts on its Inogen One concentrator line for periods ranging from 12 to 24 months after the end of the standard warranty period. Revenue from these extended service contracts is recognized in income on a straight-line basis over the contract period. Accruals for estimated standard warranty expenses are made at the time that the associated revenue is recognized. The provisions for estimated returns, discounts and warranty obligations are made based on known claims and discount commitments and estimates of additional returns and warranty obligations based on historical data and future expectations. The Company’s accrued warranty liability was $1,606 and $1,115 for future warranty costs as of June 30, 2015 and December 31, 2014, respectively. The Company also offers a lifetime warranty for direct-to-consumer sales. For a fixed price, the Company agrees to provide a fully functional oxygen concentrator for the remaining life of the patient. Lifetime warranties are only offered to patients upon the initial sale of oxygen equipment by the Company and are non-transferable. Product sales with lifetime warranties are considered to be multiple element arrangements within the scope of the Accounting Standards Codification (ASC) 605-25 —Revenue Recognition-Multiple-Element Arrangements. There are two deliverables when a product that includes a lifetime warranty is sold. The first deliverable is the oxygen concentrator equipment which comes with a standard warranty of three years. The second deliverable is the lifetime warranty that provides for a functional oxygen concentrator for the remaining lifetime of the patient. These two deliverables qualify as separate units of accounting. The revenue is allocated to the two deliverables on a relative selling price method. The Company has vendor-specific objective evidence of selling price for the equipment. To determine the selling price of the lifetime warranty, the Company uses its best estimate of the selling price for that deliverable as the lifetime warranty is neither separately priced nor is the selling price available through third-party evidence. To calculate the selling price associated with the lifetime warranties, management considered the profit margins of the overall business, the average estimated cost of lifetime warranties and the price of extended warranties. A significant estimate used to calculate the price and expense of lifetime warranties is the life expectancy of patients. Based on clinical studies, the Company estimates that 60% of patients will succumb to their disease within three years. Given the approximate mortality rate of 20% per year, the Company estimates on average all patients will succumb to their disease within five years. The Company has taken into consideration that when patients decide to buy an Inogen portable oxygen concentrator with a lifetime warranty, they typically have already been on oxygen for a period of time, which can have a large impact on their life expectancy from the time the Company’s product is deployed. After applying the relative selling price method, revenue from equipment sales is recognized when all other revenue recognition criteria for product sales are met. Lifetime warranty revenue is recognized using the straight-line method during the fourth and fifth year after the delivery of the equipment which is the estimated usage period of the contract based on the average patient life expectancy. Shipping and handling costs for sold products and rental assets shipped to the Company’s customers are included on the Statements of Operations as part of cost of sales revenue and cost of rental revenue, respectively. Revenue from the sales of used rental equipment is recognized upon shipment and when collectability is reasonably assured and other revenue recognition criteria are met. When a rental unit is sold, the related cost and accumulated depreciation are removed from their respective accounts, and any gains or losses are included in cost of sales revenue on the Statements of Operations.
Rental Revenue	Rental revenue The Company recognizes equipment rental revenue over the non-cancelable lease term, which is one month, less estimated adjustments, in accordance with ASC 840— Leases The lease term begins on the date products are shipped to patients and are recorded at amounts estimated to be received under reimbursement arrangements with third-party payors, including Medicare, private payors, and Medicaid. Due to the nature of the industry and the reimbursement environment in which the Company operates, certain estimates are required to record net revenue and accounts receivable at their net realizable values. Inherent in these estimates is the risk that they will have to be revised or updated as additional information becomes available. Specifically, the complexity of many third-party billing arrangements and the uncertainty of reimbursement amounts for certain services from certain payors may result in adjustments to amounts originally recorded. Such adjustments are typically identified and recorded at the point of cash application, claim denial or account review. Accounts receivable are reduced by an allowance for doubtful accounts which provides for those accounts from which payment is not expected to be received although product was delivered and revenue was earned. Upon determination that an account is uncollectible, it is written-off and charged to the allowance. Amounts billed but not earned due to the timing of the billing cycle are deferred and recognized in income on a straight-line basis over the monthly billing period. For example, if the first day of the billing period does not fall on the first of the month, then a portion of the monthly billing period will fall in the subsequent month and the related revenue and cost would be deferred based on the service days in the following month. Rental revenue is recognized as earned, less estimated adjustments. Revenue not billed at the end of the period is reviewed for the likelihood of collections and accrued. The rental revenue stream is not guaranteed and payment will cease if the patient no longer needs oxygen or returns the equipment. Revenue recognized is at full estimated allowable amounts; transfers to secondary insurances or patient responsibility have no net effect on revenue. Rental revenue is earned for that month if the patient is on service on the first day of the 30-day period commencing on the recurring date of service for a particular claim, regardless if there is a change in condition or death after that date. Included in rental revenue are unbilled amounts for which the revenue recognition criteria had been met as of period-end but were not yet billed to the payor. The estimate of unbilled rental revenue is based on historical trends and estimates of future collectability. In addition, the Company estimates potential future adjustments and write-offs of these unbilled amounts and includes these estimates in the allowance for adjustments and write-offs of rental revenue which is netted against gross receivables.
Fair Value of Financial Instruments	Fair value of financial instruments The Company’s financial instruments consist of cash and cash equivalents, short-term investments, accounts receivable, accounts payable and accrued expenses, debt and warrants. The carrying values of cash and cash equivalents, short-term investments, accounts receivable and accounts payable and accrued expenses approximate fair values based on the short-term nature of these financial instruments. The fair value of the Company’s debt approximates carrying value based on the Company’s current incremental borrowing rate for similar types of borrowing arrangements. Imputed interest associated with the Company’s non-interest bearing debt is insignificant and has been appropriately recognized in the respective periods. Fair value accounting 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 securities, 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 securities 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: As of December 31, 2014 Level 1 Level 2 Level 3 Total Certificates of deposit $ — $ 11,633 $ — $ 11,633 Total assets $ — $ 11,633 $ — $ 11,633 As of June 30, 2015 Level 1 Level 2 Level 3 Total Certificates of deposit $ — $ 23,587 $ — $ 23,587 Total assets $ — $ 23,587 $ — $ 23,587
Cash Equivalents	Cash Equivalents The Company considers all short-term highly liquid investments with a maturity of three months or less to be cash equivalents. Cash equivalents primarily consist of funds held in money market accounts, which were $10,100 and $42,300 as of June 30, 2015 and December 31, 2014, respectively. Cash equivalents are recorded at cost plus accrued interest, which approximates fair value. Certificates of deposit are included in cash equivalents and short-term investments based on the maturity date of the security.
Investments	Investments The Company considers investments with maturities greater than three months, but less than one year, to be short-term investments. Investments that have maturities of more than one year are classified as long-term investments. 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. The fair value measurement of the investments had an immaterial impact on Other Comprehensive Income. The Company does not have any other items which would be classified within Other Comprehensive Income. Therefore, there would be no change between the reported Net Income and Other Comprehensive Income due to the immateriality of the unrealized gains or losses associated with investments. The The Company reviews its investments to identify and evaluate investments that have an 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 interest and other income (expense), net.
Accounts receivable and allowance for bad debts, returns, and adjustments	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 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 that they become known. The 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, net of recoveries. The Company generally does not allow returns from providers for reasons not covered under its standard warranty. Therefore, provision for sales returns applies to direct-to-consumer sales only. This reserve is calculated based on actual historical return rates under the Company’s 30-day return program and is applied to the sales revenue for direct-to-consumer sales for the last month of the quarter reported. The Company also records an allowance for rental revenue adjustments and write-offs, which is recorded as a reduction of rental revenue and rental accounts receivable balances. These adjustments and write-offs result from contractual adjustments, audit adjustments, 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 reserve is based on historical revenue adjustments as a percentage of rental revenue billed and rental revenue 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 adjustments, the rental revenue adjustments account (contra rental revenue account) is charged. As of June 30, 2015 and December 31, 2014, included in accounts receivable on the balance sheets were earned but unbilled receivables of $4,141 and $3,653, respectively. These balances reflect gross unbilled receivables prior to any allowances for adjustments and write-offs.
Concentration of Credit Risk	Concentration of credit risk Financial instruments that potentially subject the Company to concentration of credit risk consist principally of cash and cash equivalents 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.
Concentration of Customers and Vendors	Concentration of customers and vendors The Company sells its products to home medical equipment providers, distributors, and resellers in the United States and in foreign countries on a credit basis. The Company sells its products to consumers on a prepayment basis. No single customer represented more than 10% of the Company’s total revenue for the six months ended June 30, 2015 and June 30, 2014. No single customer represented more than 10% of the Company’s total accounts receivable balance as of June 30, 2015, or as of December 31, 2014. 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 73.1% and 71.7% of rental revenue for the three months ended June 30, 2015 and June 30, 2014, respectively, and based on total revenue were 19.3% and 23.4% for the three months ended June 30, 2015 and June 30, 2014, respectively. Medicare’s service reimbursement programs accounted for 72.9% and 72.1% of rental revenue for the six months ended June 30, 2015 and June 30, 2014, respectively, and based on total revenue were 21.0% and 25.0% for the six months ended June 30, 2015 and June 30, 2014, respectively. Accounts receivable balances relating to Medicare’s service reimbursement programs amounted to $7,488 or 30.2% of total accounts receivable as of June 30, 2015 as compared to $4,875, or 25.2% of total accounts receivable as of December 31, 2014. 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 six months ended June 30, 2015, the Company’s three major vendors accounted for 21.6%, 17.7%, and 9.6%, respectively, of total raw material purchases. For the six months ended June 30, 2014, the Company’s three major vendors accounted for 22.6%, 18.1% and 8.5%, respectively, of total raw material purchases. A portion of revenue is earned from sales outside the United States. Approximately 70% of the non-U.S. revenue for the three months and six months ended June 30, 2015 was invoiced in euros. We did not begin to invoice in euros until the fourth quarter of 2014. A breakdown of the Company’s revenue from U.S. and non-U.S. sources for the three months and six months ended June 30, 2015 and June 30, 2014 is as follows: Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 U.S. revenue $ 33,458 $ 24,237 $ 58,812 $ 43,424 Non-U.S. revenue 10,571 6,156 18,969 10,602 Total revenue $ 44,029 $ 30,393 $ 77,781 $ 54,026
Inventories	Inventories Inventories are stated at the lower of cost or market. 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 and market represents the lower of replacement cost or estimated net realizable value. The Company records adjustments at least quarterly to inventory for potentially excess, obsolete, slow-moving or impaired items. Inventories consist of the following: June 30, December 31, 2015 2014 Raw materials and work-in-progress $ 8,118 $ 6,774 Finished goods 1,358 983 Less: reserves (168 ) (141 ) Inventories $ 9,308 $ 7,616
Property and Equipment	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 5 years Computer equipment and software 3 years Furniture and equipment 3-5 years Leasehold improvements Shorter of 3-10 years or life of underlying lease Expenditures for additions, improvements and replacements are capitalized and depreciated to a salvage value of zero. Repair and maintenance costs are included in cost of revenue on the Statements of Operations. Repair and maintenance expense, which includes labor, parts and freight for rental equipment was $642 and $400 for the three months ended June 30, 2015 and June 30, 2014, respectively, and $1,212 and $790 for the six months ended June 30, 2015 and June 30, 2014, respectively. Included within property and equipment is construction in process relating to the design and engineering of tooling, jigs and other machinery. In addition, this item also includes computer software that has been purchased, but has not completed the final configuration process for implementation into the Company’s systems. These items have not been placed in service; therefore, no depreciation and amortization has been recognized in respective periods. Depreciation and amortization expense related to property and equipment and rental equipment is summarized below for the three months ended June 30, 2015 and June 30, 2014, respectively, and for the six months ended June 30, 2015 and June 30, 2014, respectively. Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Rental equipment $ 2,944 $ 2,503 $ 5,900 $ 4,760 Other property and equipment 498 384 965 746 Total depreciation and amortization $ 3,442 $ 2,887 $ 6,865 $ 5,506 Property and equipment and rental equipment with associated accumulated depreciation is summarized below for June 30, 2015 and December 31, 2014, respectively. June 30, December 31, Property and equipment 2015 2014 Rental equipment, net of allowance $ 52,597 $ 48,359 Other property and equipment 10,663 9,408 Property and equipment 63,260 57,767 Accumulated depreciation Rental equipment 25,383 21,084 Other property and equipment 5,703 4,756 Accumulated depreciation 31,086 25,840 Net property and equipment Rental equipment 27,214 27,275 Other property and equipment 4,960 4,652 Property and equipment, net $ 32,174 $ 31,927
Income Taxes	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 operations as income tax expense. No significant interest or penalties were recognized during the periods presented. The Company operates in multiple states. The statute of limitations has expired for all tax years prior to 2011 for federal and 2010 to 2011 for various state tax purposes. However, the net operating loss generated on the federal and state tax returns in prior years may be subject to adjustments by the federal and state tax authorities. Income tax expense was $1,855 and $2,701, an effective tax rate of 34.9% and 34.9%, for the three and six months ended June 30, 2015, respectively, compared to $1,490 and $2,067, an effective tax rate of 39.5% and 39.4%, for the comparable periods ended June 30, 2014, respectively. Variations in the tax rate year-over-year were primarily due to a decrease in permanent tax differences related to the domestic production activities deduction and the California research and development tax credit.
Accounting for Stock-Based Compensation	Accounting for stock-based compensation The Company accounts for its stock-based compensation in accordance with ASC 718, Compensation—Stock Compensation As part of the provisions of ASC 718, the Company is required to estimate potential forfeitures of stock grants and adjust compensation cost recorded accordingly. The estimate of forfeitures will be adjusted over the requisite service period to the extent that actual forfeitures differ, or are expected to differ, from such estimates. Changes in estimated forfeitures will be recognized through a cumulative catch-up adjustment in the period of change and will also impact the amount of stock compensation expense to be recognized in future periods.
Business Segments	Business segments The Company operates in only one business segment – manufacturing, sales, rental and marketing of respiratory products.
Earnings Per Share	Earnings per share Earnings per share (EPS) is computed in accordance with ASC 260, Earnings per Share The shares used to compute basic and diluted net income per share represent the weighted-average common shares outstanding, reduced by the weighted-average unvested common shares subject to repurchase. The computation of EPS is as follows: Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Numerator—basic: Net income $ 3,459 $ 2,286 $ 5,031 $ 3,174 Less deemed dividend on redeemable convertible preferred stock — — — (987 ) Net income before preferred rights dividend 3,459 2,286 5,031 2,187 Less: undistributed earnings to preferred stock - basic — — — (438 ) Net income attributable to common stockholders - basic $ 3,459 $ 2,286 $ 5,031 $ 1,749 Numerator—diluted: Net income $ 3,459 $ 2,286 $ 5,031 $ 3,174 Less deemed dividend on redeemable convertible preferred stock — — — (987 ) Net income before preferred rights dividend 3,459 2,286 5,031 2,187 Less: undistributed earnings to preferred stock - diluted — — — (393 ) Net income attributable to common stockholders - diluted $ 3,459 $ 2,286 $ 5,031 $ 1,794 Denominator: Weighted-average common shares - basic common stock 19,310,064 18,201,661 19,239,218 13,843,803 Weighted-average common shares - diluted common stock 20,672,414 20,146,915 20,617,342 15,826,754 Net income per share - basic common stock $ 0.18 $ 0.13 $ 0.26 $ 0.13 Net income per share - diluted common stock $ 0.17 $ 0.11 $ 0.24 $ 0.11 Shares excluded from diluted net income: Stock options 582,970 — 612,970 — Shares excluded from diluted net income 582,970 — 612,970 — Denominator calculation from basic to diluted: Weighted-average common shares - basic common stock 19,310,064 18,201,661 19,239,218 13,843,803 Warrants 9,663 159,475 9,657 166,455 Stock options 1,352,687 1,785,779 1,368,467 1,816,496 Weighted-average common shares - diluted common stock 20,672,414 20,146,915 20,617,342 15,826,754 The computations of diluted net income attributable to common stockholders exclude common stock options which were anti-dilutive for the three months and six months ended June 30, 2015.

Summary of Significant Accoun17

Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2015
Accounting Policies [Abstract]
Summary of Fair Value Assets Measured on Recurring Basis	The following table summarizes fair value measurements by level for the assets measured at fair value on a recurring basis: As of December 31, 2014 Level 1 Level 2 Level 3 Total Certificates of deposit $ — $ 11,633 $ — $ 11,633 Total assets $ — $ 11,633 $ — $ 11,633 As of June 30, 2015 Level 1 Level 2 Level 3 Total Certificates of deposit $ — $ 23,587 $ — $ 23,587 Total assets $ — $ 23,587 $ — $ 23,587
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 70% of the non-U.S. revenue for the three months and six months ended June 30, 2015 was invoiced in euros. We did not begin to invoice in euros until the fourth quarter of 2014. A breakdown of the Company’s revenue from U.S. and non-U.S. sources for the three months and six months ended June 30, 2015 and June 30, 2014 is as follows: Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 U.S. revenue $ 33,458 $ 24,237 $ 58,812 $ 43,424 Non-U.S. revenue 10,571 6,156 18,969 10,602 Total revenue $ 44,029 $ 30,393 $ 77,781 $ 54,026
Schedule of Inventories	Inventories consist of the following: June 30, December 31, 2015 2014 Raw materials and work-in-progress $ 8,118 $ 6,774 Finished goods 1,358 983 Less: reserves (168 ) (141 ) Inventories $ 9,308 $ 7,616
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 5 years Computer equipment and software 3 years Furniture and equipment 3-5 years Leasehold improvements Shorter of 3-10 years or life of underlying lease
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 is summarized below for the three months ended June 30, 2015 and June 30, 2014, respectively, and for the six months ended June 30, 2015 and June 30, 2014, respectively. Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Rental equipment $ 2,944 $ 2,503 $ 5,900 $ 4,760 Other property and equipment 498 384 965 746 Total depreciation and amortization $ 3,442 $ 2,887 $ 6,865 $ 5,506
Summary of Property Plant and Equipment and Rental Equipment with Associated Accumulated Depreciation	Property and equipment and rental equipment with associated accumulated depreciation is summarized below for June 30, 2015 and December 31, 2014, respectively. June 30, December 31, Property and equipment 2015 2014 Rental equipment, net of allowance $ 52,597 $ 48,359 Other property and equipment 10,663 9,408 Property and equipment 63,260 57,767 Accumulated depreciation Rental equipment 25,383 21,084 Other property and equipment 5,703 4,756 Accumulated depreciation 31,086 25,840 Net property and equipment Rental equipment 27,214 27,275 Other property and equipment 4,960 4,652 Property and equipment, net $ 32,174 $ 31,927
Computation of Earnings Per Share	The computation of EPS is as follows: Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Numerator—basic: Net income $ 3,459 $ 2,286 $ 5,031 $ 3,174 Less deemed dividend on redeemable convertible preferred stock — — — (987 ) Net income before preferred rights dividend 3,459 2,286 5,031 2,187 Less: undistributed earnings to preferred stock - basic — — — (438 ) Net income attributable to common stockholders - basic $ 3,459 $ 2,286 $ 5,031 $ 1,749 Numerator—diluted: Net income $ 3,459 $ 2,286 $ 5,031 $ 3,174 Less deemed dividend on redeemable convertible preferred stock — — — (987 ) Net income before preferred rights dividend 3,459 2,286 5,031 2,187 Less: undistributed earnings to preferred stock - diluted — — — (393 ) Net income attributable to common stockholders - diluted $ 3,459 $ 2,286 $ 5,031 $ 1,794 Denominator: Weighted-average common shares - basic common stock 19,310,064 18,201,661 19,239,218 13,843,803 Weighted-average common shares - diluted common stock 20,672,414 20,146,915 20,617,342 15,826,754 Net income per share - basic common stock $ 0.18 $ 0.13 $ 0.26 $ 0.13 Net income per share - diluted common stock $ 0.17 $ 0.11 $ 0.24 $ 0.11 Shares excluded from diluted net income: Stock options 582,970 — 612,970 — Shares excluded from diluted net income 582,970 — 612,970 — Denominator calculation from basic to diluted: Weighted-average common shares - basic common stock 19,310,064 18,201,661 19,239,218 13,843,803 Warrants 9,663 159,475 9,657 166,455 Stock options 1,352,687 1,785,779 1,368,467 1,816,496 Weighted-average common shares - diluted common stock 20,672,414 20,146,915 20,617,342 15,826,754

Long-Term Debt (Tables)

Long-Term Debt (Tables)	6 Months Ended
	Jun. 30, 2015
Debt Disclosure [Abstract]
Schedule of Long-Term Debt	June 30, December 31, 2015 2014 Contractual obligation, bearing imputed interest at prime plus two, quarterly payments of $53 beginning May 2011 through October 2014 and quarterly payments of $81 beginning January 2015 through October 2016 $ 466 $ 614 Less: current maturities (307 ) (299 ) Long-term debt, net of current portion $ 159 $ 315
Schedule of Minimum Aggregate Payments Due Under Non-Cancelable Debt	As of June 30, 2015, the minimum aggregate payments due under non-cancelable debt are summarized as follows: June 30, 2015 Remaining 6 months of 2015 $ 151 2016 315 Total $ 466

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2015
Commitments And Contingencies Disclosure [Abstract]
Minimum Aggregate Payments Due under Non-Cancelable Leases	The Company leases its offices and certain equipment under operating leases that expire through January 2022. As of June 30, 2015, the minimum aggregate payments due under non-cancelable leases are summarized as follows: June 30, 2015 Remaining 6 months of 2015 $ 512 2016 1,041 2017 1,052 2018 1,044 2019 1,057 Thereafter 819 $ 5,525
Schedule of Changes in Aggregate Product Warranty Liabilities	The following table identifies the changes in the Company’s aggregate product warranty liabilities for the six and twelve month periods ended June 30, 2015 and December 31, 2014, respectively: June 30, December 31, 2015 2014 Product warranty liability at beginning of period $ 1,115 $ 809 Accruals for warranties issued 927 1,075 Adjustments related to preexisting warranties (including changes in estimates) 260 406 Settlements made (in cash or in kind) (696 ) (1,175 ) Product warranty liability at end of period $ 1,606 $ 1,115

Stock Incentive Plans (Tables)

Stock Incentive Plans (Tables)	6 Months Ended
	Jun. 30, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Options Activity	The activity for stock options under the Company’s stock plans is as follows: Options Price per share Weighted-average exercise price Remaining weighted-average contractual terms (in years) Per share average intrinsic value Outstanding as of December 31, 2014 2,261,633 $0.60-$24.52 $ 7.31 6.43 $ 24.06 Granted 582,970 38.54 38.54 Exercised (268,228 ) 0.60-16.62 1.41 Forfeited (9,786 ) 0.75-16.62 4.46 Expired — — — Outstanding as of June 30, 2015 2,566,589 0.60-38.54 15.03 6.24 29.57 Vested and exercisable as of June 30, 2015 1,112,609 0.60-18.93 4.39 5.59 40.21 Vested and expected to vest as of June 30, 2015 2,438,494 $0.60-$38.54 $ 14.84 6.20 $ 29.76
Summary of ESPP Activity	The activity for the ESPP is as follows: First Offering Second Offering Period Period Employee accumulated payroll deductions $ 414 $ 343 Total shares purchased 30,358 18,551 Payroll deductions used to purchase shares $ 413 $ 342 Transfer to next offering period $ 1 $ 1 FMV at enrollment date per share $ 16.00 $ 21.69 FMV at purchase date per share $ 21.69 $ 33.62 Purchase price per share $ 13.60 $ 18.44

Warrants (Tables)

Warrants (Tables)	6 Months Ended
	Jun. 30, 2015
Equity [Abstract]
Summary of Outstanding Warrants	A summary of outstanding common stock warrants as of June 30, 2015 is as follows: Number of Exercise Expiration Security warrants price/share date Common stock 15,218 $ 0.30 2017-2019

General - Additional Informatio

General - Additional Information (Details) $ / shares in Units, $ in Thousands	Feb. 20, 2014USD ($)$ / sharesshares	Jun. 30, 2015USD ($)lbshares	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)Customerlbshares	Jun. 30, 2014USD ($)	Dec. 31, 2014USD ($)shares	Dec. 31, 2009USD ($)
General Disclosures [Line Items]
Revenues | $		$ 44,029	$ 30,393	$ 77,781	$ 54,026
Common stock, shares outstanding		19,346,143		19,346,143		19,059,364
Deemed dividend on redeemable convertible preferred stock | $					987
Redeemable Convertible Preferred Stock
General Disclosures [Line Items]
Preferred stock outstanding		0		0		0
Convertible Preferred Stock
General Disclosures [Line Items]
Preferred stock outstanding		0		0		0
Initial Public Offering (IPO)
General Disclosures [Line Items]
Number of shares sold	4,511,313
Shares sold, price per share | $ / shares	$ 16
Amount after underwriters’ discount and other associated expenses | $	$ 49,668
Initial Public Offering (IPO) | Common stock
General Disclosures [Line Items]
Conversion of preferred stock, shares	14,259,647
Initial Public Offering (IPO) | Stockholders
General Disclosures [Line Items]
Number of shares sold	981,902
Initial Public Offering (IPO) | Redeemable Convertible Preferred Stock
General Disclosures [Line Items]
Convertible preferred stock, shares issued upon conversion	9,546,140
Deemed dividend on redeemable convertible preferred stock | $					$ 987
Initial Public Offering (IPO) | Convertible Preferred Stock
General Disclosures [Line Items]
Convertible preferred stock, shares issued upon conversion	66,666
Initial Public Offering (IPO) | Inogen, Inc.
General Disclosures [Line Items]
Number of shares sold	3,529,411
Comfort Life Medical, LLC
General Disclosures [Line Items]
Revenues | $						$ 112,500	$ 10,700
One G3
General Disclosures [Line Items]
Weight of oxygen portable device | lb		4.8		4.8
One G2
General Disclosures [Line Items]
Weight of oxygen portable device | lb		7		7
Maximum
General Disclosures [Line Items]
Percentage of patients using portable oxygen concentrators				7.00%
Maximum | One G3
General Disclosures [Line Items]
Estimated battery life of portable oxygen concentrator				4 hours 30 minutes
Maximum | One G2
General Disclosures [Line Items]
Estimated battery life of portable oxygen concentrator				5 hours
Minimum
General Disclosures [Line Items]
Percentage of patients using portable oxygen concentrators				5.00%
Minimum | Inogen One
General Disclosures [Line Items]
Number of customers served over several years | Customer				97,000

Summary of Significant Accoun23

Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)CustomerProductSegment	Jun. 30, 2014USD ($)Customer	Dec. 31, 2014USD ($)Customer	Dec. 31, 2013USD ($)
Significant Accounting Policies [Line Items]
Extended service contracts			The second deliverable is the lifetime warranty that provides for a functional oxygen concentrator for the remaining lifetime of the patient
Accrual of product warranty liability	$ 1,606,000		$ 1,606,000		$ 1,115,000	$ 809,000
Standard product warranty description			The first deliverable is the oxygen concentrator equipment which comes with a standard warranty of three years
Number of deliverables qualifying as separate units | Product			2
Estimation for sale of products			the Company estimates that 60% of patients will succumb to their disease within three years. Given the approximate mortality rate of 20% per year, the Company estimates on average all patients will succumb to their disease within five years.
Rental revenue earned			30-day period
Funds held in money market	10,100,000		$ 10,100,000		42,300,000
Unbilled Receivables	4,141,000		4,141,000		3,653,000
Accounts Receivable Net Current	$ 24,765,000		$ 24,765,000		19,349,000
Percentage of Non-US revenue invoiced in Euros	70.00%		70.00%
Salvage value of expenditures for additions, improvements and replacements	$ 0		$ 0
Repairs and maintenance expense	642,000	$ 400,000	1,212,000	$ 790,000
Depreciation and amortization	3,442,000	2,887,000	6,865,000	5,506,000
Provision for income taxes	$ 1,855,000	$ 1,490,000	$ 2,701,000	$ 2,067,000
Effective tax rate	34.90%	39.50%	34.90%	39.40%
Number of business segment | Segment			1
Construction In Progress And Computer Software
Significant Accounting Policies [Line Items]
Depreciation and amortization	$ 0	$ 0	$ 0	$ 0
Customer Concentration Risk
Significant Accounting Policies [Line Items]
Accounts Receivable Net Current	$ 7,488,000		$ 7,488,000		$ 4,875,000
Sales Revenue, Net
Significant Accounting Policies [Line Items]
Number of customers | Customer			0	0
Sales Revenue, Net | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Concentration risk, percentage	19.30%	23.40%	21.00%	25.00%
Accounts Receivable
Significant Accounting Policies [Line Items]
Number of customers | Customer			0		0
Accounts Receivable | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Concentration risk, percentage	30.20%				25.20%
Sales Revenue, Services, Net | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Concentration risk, percentage	73.10%	71.70%	72.90%	72.10%
Raw materials | Supplier Concentration Risk | Vendor one
Significant Accounting Policies [Line Items]
Concentration risk, percentage			21.60%	22.60%
Raw materials | Supplier Concentration Risk | Vendor two
Significant Accounting Policies [Line Items]
Concentration risk, percentage			17.70%	18.10%
Raw materials | Supplier Concentration Risk | Vendor three
Significant Accounting Policies [Line Items]
Concentration risk, percentage			9.60%	8.50%
Service Contracts
Significant Accounting Policies [Line Items]
Extended service contracts			The Company offers extended service contracts on its Inogen One concentrator line for periods ranging from 12 to 24 months after the end of the standard warranty period.

Summary of Significant Accoun24

Summary of Significant Accounting Policies - Summary of Fair Value Assets Measured on Recurring Basis (Details) - Fair Value Measurements, Recurring - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	$ 23,587	$ 11,633
Certificates Of Deposit
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	23,587	11,633
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	23,587	11,633
Level 2 | Certificates Of Deposit
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	$ 23,587	$ 11,633

Summary of Significant Accoun25

Summary of Significant Accounting Policies - Breakdown of the Company Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Concentration Risk [Line Items]
Revenues	$ 44,029	$ 30,393	$ 77,781	$ 54,026
U.S. revenue
Concentration Risk [Line Items]
Revenues	33,458	24,237	58,812	43,424
Non-U.S. revenue
Concentration Risk [Line Items]
Revenues	$ 10,571	$ 6,156	$ 18,969	$ 10,602

Summary of Significant Accoun26

Summary of Significant Accounting Policies - Schedule of Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Inventory Disclosure [Abstract]
Raw materials and work-in-progress	$ 8,118	$ 6,774
Finished goods	1,358	983
Less: reserves	(168)	(141)
Inventories	$ 9,308	$ 7,616

Summary of Significant Accoun27

Summary of Significant Accounting Policies - Computation of Depreciation and Amortization Using Straight Line Method Over Estimated Useful Lives of Assets (Details)	6 Months Ended
	Jun. 30, 2015
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
Property Plant And Equipment [Line Items]
Property Plant And Equipment Useful Life	5 years
Computer equipment and software
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	Shorter of 3-10 years or life of underlying lease

Summary of Significant Accoun28

Summary of Significant Accounting Policies - Summary of Depreciation and Amortization Expense of Property and Equipment and Rental Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Property Plant And Equipment [Line Items]
Depreciation and amortization	$ 3,442	$ 2,887	$ 6,865	$ 5,506
Equipment
Property Plant And Equipment [Line Items]
Depreciation	2,944	2,503	5,900	4,760
Other property and equipment
Property Plant And Equipment [Line Items]
Depreciation and amortization	$ 498	$ 384	$ 965	$ 746

Summary of Significant Accoun29

Summary of Significant Accounting Policies - Summary of Property Plant and Equipment and Rental Equipment with Associated Accumulated Depreciation (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Property Plant And Equipment [Line Items]
Property and equipment	$ 63,260	$ 57,767
Accumulated depreciation	31,086	25,840
Property and equipment, net	32,174	31,927
Equipment
Property Plant And Equipment [Line Items]
Property and equipment	52,597	48,359
Accumulated depreciation	25,383	21,084
Property and equipment, net	27,214	27,275
Other property and equipment
Property Plant And Equipment [Line Items]
Property and equipment	10,663	9,408
Accumulated depreciation	5,703	4,756
Property and equipment, net	$ 4,960	$ 4,652

Summary of Significant Accoun30

Summary of Significant Accounting Policies - Computation of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Numerator—basic:
Net income	$ 3,459	$ 2,286	$ 5,031	$ 3,174
Less deemed dividend on redeemable convertible preferred stock				(987)
Net income before preferred rights dividend	3,459	2,286	5,031	2,187
Less: undistributed earnings to preferred stock - basic				(438)
Net income attributable to common stockholders - basic	3,459	2,286	5,031	1,749
Numerator—diluted:
Net income	3,459	2,286	5,031	3,174
Less deemed dividend on redeemable convertible preferred stock				(987)
Net income before preferred rights dividend	3,459	2,286	5,031	2,187
Less: undistributed earnings to preferred stock - diluted				(393)
Net income attributable to common stockholders - diluted	$ 3,459	$ 2,286	$ 5,031	$ 1,794
Denominator:
Weighted-average common shares - basic common stock	19,310,064	18,201,661	19,239,218	13,843,803
Weighted-average common shares - diluted common stock	20,672,414	20,146,915	20,617,342	15,826,754
Net income per share - basic common stock	$ 0.18	$ 0.13	$ 0.26	$ 0.13
Net income per share - diluted common stock	$ 0.17	$ 0.11	$ 0.24	$ 0.11
Shares excluded from diluted net income:
Shares excluded from diluted net income	582,970		612,970
Weighted-average number of shares used in calculating net income per share attributable to common stockholders:
Weighted-average common shares - basic common stock	19,310,064	18,201,661	19,239,218	13,843,803
Warrants	9,663	159,475	9,657	166,455
Stock options	1,352,687	1,785,779	1,368,467	1,816,496
Weighted-average common shares - diluted common stock	20,672,414	20,146,915	20,617,342	15,826,754
Stock Options
Shares excluded from diluted net income:
Shares excluded from diluted net income	582,970		612,970

Intangible Assets - Additional

Intangible Assets - Additional Information (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2011USD ($)	Dec. 31, 2009USD ($)Patents	Dec. 31, 2008USD ($)
Finite Lived Intangible Assets [Line Items]
Estimated useful life of intangible asset			2 years
Purchased additional patents			$ 11	$ 180
Amortization of intangible assets	$ 22	$ 41	43	80
Production of commercials
Finite Lived Intangible Assets [Line Items]
Cost incurred for advertising			$ 11
Patient setup video, Website development, redesign and commercials
Finite Lived Intangible Assets [Line Items]
Cost incurred for advertising		11		180
Air Products & Chemicals
Finite Lived Intangible Assets [Line Items]
Acquisition of intangible asset							$ 250
Estimated useful life of intangible asset			5 years
Impairments	0	0	$ 0	0
Number of patents | Patents							4
Increase in long term liability			$ 250
Purchased additional patents						$ 650
Comfort Life Medical, LLC
Finite Lived Intangible Assets [Line Items]
Acquisition of intangible asset								$ 92
Estimated useful life of intangible asset			10 years
Impairments			$ 0		$ 0
Breathe Oxygen Services, LLC
Finite Lived Intangible Assets [Line Items]
Acquisition of intangible asset						$ 66
Estimated useful life of intangible asset						10 years
Impairments	$ 0	$ 0	$ 0	$ 0

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Details) - JP Morgan Chase Debt - USD ($)	Nov. 30, 2014	Jun. 30, 2016	Jun. 30, 2015
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 15,000,000
Percentage of margin rate	1.25%
Earnings before interest, taxes, depreciation and amortization	$ 10,000,000
Amount outstanding			$ 0
Minimum
Debt Instrument [Line Items]
Tangible net worth	$ 90,000,000
Scenario Forecast
Debt Instrument [Line Items]
Earnings before interest, taxes, depreciation and amortization		$ 12,500,000

Long-Term Debt - Schedule of Lo

Long-Term Debt - Schedule of Long-Term Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Long term debt	$ 466
Less: current maturities	(307)	$ (299)
Long-term debt, net of current portion	159	315
Contractual Obligation
Debt Instrument [Line Items]
Long term debt	$ 466	$ 614

Long-Term Debt - Schedule of 34

Long-Term Debt - Schedule of Long-Term Debt (Parenthetical) (Detail) $ in Thousands	3 Months Ended
	Jun. 30, 2015USD ($)
May 2011 Through October 2014
Debt Instrument [Line Items]
Long-term debt, quarterly payments	$ 53
January 2015 through October 2016
Debt Instrument [Line Items]
Long-term debt, quarterly payments	$ 81

Long-Term Debt - Schedule of Mi

Long-Term Debt - Schedule of Minimum Aggregate Payments due under Non-Cancelable Debt (Details) $ in Thousands	Jun. 30, 2015USD ($)
Debt Disclosure [Abstract]
Remaining 6 months of 2015	$ 151
2,016	315
Long term debt	$ 466

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Commitments And Contingencies [Line Items]
Rent expense	$ 220	$ 180	$ 440	$ 387
Offices and Certain Equipment
Commitments And Contingencies [Line Items]
Operating leases expiration date			Jan. 31, 2022

Commitments and Contingencies37

Commitments and Contingencies - Minimum Aggregate Payments Due under Non-Cancelable Leases (Details) $ in Thousands	Jun. 30, 2015USD ($)
Commitments And Contingencies Disclosure [Abstract]
Remaining 6 months of 2015	$ 512
2,016	1,041
2,017	1,052
2,018	1,044
2,019	1,057
Thereafter	819
Total minimum payments	$ 5,525

Commitments and Contingencies38

Commitments and Contingencies - Schedule of Changes in Aggregate Product Warranty Liabilities (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Commitments And Contingencies Disclosure [Abstract]
Product warranty liability at beginning of period	$ 1,115	$ 809
Accruals for warranties issued	927	1,075
Adjustments related to preexisting warranties (including changes in estimates)	260	406
Settlements made (in cash or in kind)	(696)	(1,175)
Product warranty liability at end of period	$ 1,606	$ 1,115

Stock Incentive Plans - Additio

Stock Incentive Plans - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 809	$ 535	$ 1,327	$ 666
Rate of reduced stock-based compensation expense for estimated forfeiture			7.50%	7.30%
Share-based compensation, unrecognized expense, nonvested granted awards	$ 11,830	$ 5,438	$ 11,830	$ 5,438
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option period, expiration			10 years
Stock option period, vested			4 years
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option period, expiration			7 years
Stock option period, vested			1 year
2012 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option shares outstanding	713,776		713,776
Number of equity awards available for grant	0		0
2002 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option shares outstanding	548,249		548,249
Number of equity awards available for grant	0		0
2014 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option shares outstanding	1,304,564		1,304,564
Number of equity awards available for grant	410,367		410,367		221,178
Common stock reserved for future issuance	1,724,487		1,724,487
Terms of shares available for issuance			The number of shares available for issuance under the 2014 Plan also includes an annual increase on the first day of each fiscal year beginning in 2015, equal to the least of: 895,346 shares; 4% of the outstanding shares of common stock as of the last day of our immediately preceding fiscal year; or such other amount as our 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			762,373
2012 Plan and 2002 Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option shares outstanding	2,328,569		2,328,569
2014 ESPP Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	309,299		309,299
Terms of shares available for issuance			The number of shares available for issuance under the 2014 ESPP Plan also includes an annual increase on the first day of each fiscal year beginning in 2015, equal to least of: 179,069 shares;1.5% of the outstanding shares of our common stock on the last day of our 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
Potential increase of shares available for issuance	179,069		179,069
Purchase price as percentage of stock price on offering period			85.00%
Purchase price as percentage of stock price on exercise date			85.00%
Stock-based compensation expense	$ 105		$ 190

Stock Incentive Plans - Summary

Stock Incentive Plans - Summary of Stock Options Activity (Details) - $ / shares	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock Options Outstanding, Beginning balance	2,261,633
Stock Options, Granted	582,970
Stock Options, Exercised	(268,228)
Stock Options, Forfeited	(9,786)
Stock Options Outstanding, Ending balance	2,566,589	2,261,633
Stock Options, Vested and exercisable	1,112,609
Stock Options, Vested and expected to vest	2,438,494
Price per share, Granted	$ 38.54
Outstanding, Weighted average exercise price, Beginning balance	7.31
Weighted average exercise price, Granted	38.54
Weighted average exercise price, Exercised	1.41
Weighted average exercise price, Forfeited	4.46
Outstanding, Weighted average exercise price, Ending balance	15.03	$ 7.31
Weighted average exercise price, Vested and exercisable	4.39
Weighted average exercise price, Vested and expected to vest	$ 14.84
Remaining weighted average contractual term, Outstanding	6 years 2 months 27 days	6 years 5 months 5 days
Remaining weighted average contractual term, Vested and exercisable	5 years 7 months 2 days
Remaining weighted average contractual term, Vested and expected to vest	6 years 2 months 12 days
Outstanding, Per share average intrinsic value	$ 29.57	$ 24.06
Per share average intrinsic value, Vested and exercisable	40.21
Per share average intrinsic value, Vested and expected to vest	29.76
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding, Price per share, Beginning balance	0.60
Price per share, Exercised	0.60
Price per share, Forfeited	0.75
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
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding, Price per share, Beginning balance	24.52
Price per share, Exercised	16.62
Price per share, Forfeited	16.62
Outstanding, Price per share, Ending balance	38.54	$ 24.52
Price per share, Vested and exercisable	18.93
Price per share, Vested and expected to vest	$ 38.54

Stock Incentive Plans - Summa41

Stock Incentive Plans - Summary of ESPP Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 01, 2014	Mar. 03, 2014	Jun. 30, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Payroll deductions used to purchase shares			$ 342
2014 ESPP Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Employee accumulated payroll deductions	$ 343	$ 414
Total shares purchased	18,551	30,358
Payroll deductions used to purchase shares	$ 342	$ 413
Transfer to next offering period	$ 1	$ 1
FMV at enrollment date per share	$ 21.69	$ 16
FMV at purchase date per share	33.62	21.69
Purchase price per share	$ 18.44	$ 13.60

Warrants - Summary of Outstandi

Warrants - Summary of Outstanding Warrants (Details) - Jun. 30, 2015 - Common stock - 2017-2019 - $ / shares	Total
Class Of Warrant Or Right [Line Items]
Number of warrants	15,218
Exercise price/share	$ 0.30
Minimum
Class Of Warrant Or Right [Line Items]
Expiration date	2,017
Maximum
Class Of Warrant Or Right [Line Items]
Expiration date	2,019