Inogen (INGN) 10-Q 4 May 21 2021 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2021	Apr. 30, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Trading Symbol	INGN
Entity Registrant Name	INOGEN, INC.
Entity Central Index Key	0001294133
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		22,395,360
Document Quarterly Report	true
Document Transition Report	false
Title of 12(b) Security	Common Stock, $0.001 par value
Security Exchange Name	NASDAQ
Entity File Number	001-36309
Entity Tax Identification Number	33-0989359
Entity Address, Address Line One	301 Coromar Drive
Entity Address, City or Town	Goleta
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	93117
City Area Code	(805)
Local Phone Number	562-0500
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	DE

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 220,014	$ 211,962
Marketable securities	13,136	19,257
Accounts receivable, net	38,425	29,717
Inventories, net	26,394	24,815
Income tax receivable	1,984	2,048
Prepaid expenses and other current assets	9,723	17,898
Total current assets	309,676	305,697
Property and equipment
Rental equipment, net	49,872	46,953
Manufacturing equipment and tooling	10,811	10,361
Computer equipment and software	7,454	7,356
Furniture and equipment	2,293	2,293
Leasehold improvements	4,592	4,592
Land and building	125	125
Construction in process	3,367	2,344
Total property and equipment	78,514	74,024
Less accumulated depreciation	(47,461)	(45,794)
Property and equipment, net	31,053	28,230
Goodwill	33,055	33,165
Intangible assets, net	66,557	68,797
Operating lease right-of-use asset	17,521	8,827
Deferred tax asset - noncurrent	15,994	14,467
Other assets	2,619	2,669
Total assets	476,475	461,852
Current liabilities
Accounts payable and accrued expenses	29,349	33,712
Accrued payroll	9,191	7,091
Warranty reserve - current	5,701	5,740
Operating lease liability - current	2,475	1,931
Deferred revenue - current	7,492	6,994
Income tax payable	1,264	1,242
Total current liabilities	55,472	56,710
Long-term liabilities
Warranty reserve - noncurrent	9,213	8,654
Operating lease liability - noncurrent	16,435	8,078
Earnout liability - noncurrent	27,205	26,940
Deferred revenue - noncurrent	11,842	11,822
Deferred tax liability - noncurrent	24	25
Total liabilities	120,191	112,229
Commitments and contingencies (Note 9)
Stockholders' equity
Common stock, $0.001 par value per share; 200,000,000 authorized; 22,385,794 and 22,131,447 shares issued and outstanding as of March 31, 2021 and December 31, 2020, respectively	22	22
Additional paid-in capital	280,464	273,521
Retained earnings	74,873	75,605
Accumulated other comprehensive income	925	475
Total stockholders' equity	356,284	349,623
Total liabilities and stockholders' equity	$ 476,475	$ 461,852

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	22,385,794	22,131,447
Common stock, shares outstanding	22,385,794	22,131,447

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenue
Sales revenue	$ 77,081	$ 83,140
Rental revenue	9,851	5,349
Total revenue	86,932	88,489
Cost of revenue
Cost of sales revenue	42,635	47,118
Cost of rental revenue, including depreciation of $1,888 and $1,299, respectively	4,424	3,005
Total cost of revenue	47,059	50,123
Gross profit
Gross profit-sales revenue	34,446	36,022
Gross profit-rental revenue	5,427	2,344
Total gross profit	39,873	38,366
Operating expense
Research and development	4,015	3,605
Sales and marketing	25,491	27,163
General and administrative	12,499	9,777
Total operating expense	42,005	40,545
Loss from operations	(2,132)	(2,179)
Other income (expense)
Interest income	57	552
Other expense	(310)	(60)
Total other income (expense), net	(253)	492
Loss before benefit for income taxes	(2,385)	(1,687)
Benefit for income taxes	(1,653)	(98)
Net loss	(732)	(1,589)
Other comprehensive income (loss), net of tax
Change in foreign currency translation adjustment	(457)	(158)
Change in net unrealized gains (losses) on foreign currency hedging	1,144	661
Less: reclassification adjustment for net (gains) losses included in net income	(241)	12
Total net change in unrealized gains (losses) on foreign currency hedging	903	673
Change in net unrealized gains (losses) on marketable securities	4	(6)
Total other comprehensive income, net of tax	450	509
Comprehensive loss	$ (282)	$ (1,080)
Basic net loss per share attributable to common stockholders (Note 6)	$ (0.03)	$ (0.07)
Diluted net loss per share attributable to common stockholders (Note 6)	$ (0.03)	$ (0.07)
Weighted-average number of shares used in calculating net loss per share attributable to common stockholders:
Basic common shares	22,181,394	21,916,365
Diluted common shares	22,181,394	21,916,365

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Loss (Parenthetical) (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Depreciation	$ 1,888	$ 1,299

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income (loss)
Beginning Balance at Dec. 31, 2019	$ 344,621	$ 22	$ 263,252	$ 81,434	$ (87)
Beginning Balance, shares at Dec. 31, 2019		22,031,410
Stock-based compensation	2,784		2,784
Employee stock purchases	1,088		1,088
Employee stock purchases, shares		27,954
Restricted stock awards issued, net of forfeitures, shares		(27,729)
Vesting of restricted stock units	(7)		(7)
Vesting of restricted stock units, shares		10,167
Shares withheld related to net restricted stock settlement	(166)		(166)
Shares withheld related to net restricted stock settlement, shares		(3,609)
Stock options exercised	60		60
Stock options exercised, shares		6,334
Net loss	(1,589)			(1,589)
Other comprehensive income	509				509
Ending Balance at Mar. 31, 2020	347,300	$ 22	267,011	79,845	422
Ending Balance, shares at Mar. 31, 2020		22,044,527
Beginning Balance at Dec. 31, 2020	349,623	$ 22	273,521	75,605	475
Beginning Balance, shares at Dec. 31, 2020		22,131,447
Stock-based compensation	2,516		2,516
Employee stock purchases	927		927
Employee stock purchases, shares		37,699
Restricted stock awards issued, net of forfeitures, shares		(21,509)
Vesting of restricted stock units	(275)		(275)
Vesting of restricted stock units, shares		34,117
Shares withheld related to net restricted stock settlement	(91)		(91)
Shares withheld related to net restricted stock settlement, shares		(1,713)
Stock options exercised	$ 3,866		3,866
Stock options exercised, shares	205,753	205,753
Net loss	$ (732)			(732)
Other comprehensive income	450				450
Ending Balance at Mar. 31, 2021	$ 356,284	$ 22	$ 280,464	$ 74,873	$ 925
Ending Balance, shares at Mar. 31, 2021		22,385,794

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities
Net loss	$ (732)	$ (1,589)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	5,098	4,462
Loss on rental units and other fixed assets	158	130
Gain on sale of former rental assets	(24)	(37)
Provision for sales revenue returns and doubtful accounts	2,471	3,608
Provision for rental revenue adjustments	1,041	808
Provision for inventory losses	518	347
Stock-based compensation expense	2,516	2,784
Deferred income taxes	(1,527)	(200)
Change in fair value of earnout liability	265	(952)
Changes in operating assets and liabilities:
Accounts receivable	(12,418)	(10,511)
Inventories	(2,686)	(3,721)
Income tax receivable	64	213
Prepaid expenses and other current assets	8,171	(3,710)
Operating lease right-of-use asset	(8,696)	(2,262)
Other noncurrent assets	41	460
Accounts payable and accrued expenses	(3,526)	2,759
Accrued payroll	2,105	2,436
Warranty reserve	520	1,000
Deferred revenue	518	149
Income tax payable	80	103
Operating lease liability	8,903	4,263
Net cash provided by operating activities	2,860	540
Cash flows from investing activities
Maturities of marketable securities	6,125	11,051
Investment in intangible assets	(26)
Investment in property and equipment	(1,516)	(1,479)
Production and purchase of rental equipment	(3,643)	(735)
Proceeds from sale of former assets	46	62
Net cash provided by investing activities	986	8,899
Cash flows from financing activities
Proceeds from stock options exercised	3,866	60
Proceeds from employee stock purchases	927	1,088
Payment of employment taxes related to release of restricted stock	(366)	(173)
Net cash provided by financing activities	4,427	975
Effect of exchange rates on cash	(221)	(89)
Net increase in cash and cash equivalents	8,052	10,325
Cash and cash equivalents, beginning of period	211,962	198,037
Cash and cash equivalents, end of period	220,014	208,362
Supplemental disclosures of cash flow information
Cash paid during the period for income taxes, net of refunds received	17
Supplemental disclosure of non-cash transactions
Property and equipment in accounts payable and accrued liabilities	$ 77	$ 38

Business Overview

Business Overview	3 Months Ended
	Mar. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Business Overview	1. Business overview Inogen, Inc. (Company or Inogen) was incorporated in Delaware on November 27, 2001. The Company is a medical technology company that primarily develops, manufactures and markets innovative portable oxygen concentrators (POCs) 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 ® Since adopting the Company’s direct-to-consumer rental strategy in 2009, the Company has directly sold or rented more than 1,023,000 of its Inogen oxygen concentrators as of March 31, 2021. The Company incorporated Inogen Europe Holding B.V., a Dutch limited liability company, on April 13, 2017. On May 4, 2017, Inogen Europe Holding B.V. acquired all issued and outstanding capital stock of MedSupport Systems B.V. (MedSupport) and began operating under the name Inogen Europe B.V. The Company merged Inogen Europe Holding B.V. and Inogen Europe B.V. on December 28, 2018. Inogen Europe B.V. is the remaining legal entity. Inogen completed the acquisition of New Aera, Inc. (New Aera) on August 9, 2019.

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	2. Basis of presentation and summary of significant accounting policies The consolidated financial statements of the Company have been prepared in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP). The results of operations for the three months ended March 31, 2021 shown in this report are not necessarily indicative of results to be expected for the full year ending December 31, 2021. In the opinion of the Company’s management, the information contained herein reflects all adjustments, consisting of only normal recurring adjustments, necessary for a fair presentation of the Company’s results of operations, financial position, cash flows and stockholders’ equity. Certain footnote disclosures normally included in annual consolidated financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to Securities and Exchange Commission (SEC) rules and regulations relating to interim financial statements. The accompanying consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K filed with the SEC on February 24, 2021. Except as further described below, there have been no significant changes in the Company’s accounting policies from those disclosed in its Annual Report on Form 10-K filed with the SEC on February 24, 2021. Basis of consolidation The consolidated financial statements include the accounts of Inogen, Inc. and its wholly owned subsidiary. All intercompany balances and transactions have been eliminated. Use of estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Management bases these estimates and assumptions upon historical experience, existing and known circumstances, authoritative accounting pronouncements and other factors that management believes to be reasonable. Significant areas requiring the use of management estimates relate to revenue recognition, warranty reserves and expense, determining the stand-alone selling price (SSP) and service period of performance obligations, rental asset valuations and write-downs, accounts receivable allowances for bad debts, returns and adjustments, impairment of long-lived assets, stock -based compensation expense, income ta xes , fair value of acquired intangible assets and goodwill and fair value of earnout liabilities . Actual results could differ from these estimates. Recently adopted accounting pronouncements In December 2019, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. The new guidance simplifies the accounting for income taxes by removing certain exceptions to the general principles in Topic 740. The new guidance also improves consistent application of and simplifies U.S. GAAP for other areas of Topic 740 by clarifying and amending the existing guidance Business segments The Company operates and reports in only one operating and reportable segment – development, manufacturing, marketing, sales, and rental of respiratory products. Management reports financial information on a consolidated basis to the Company’s chief operating decision maker.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair value measurements Accounting Standards Codification (ASC) 820 — Fair Value Measurements and Disclosures Level input Input definition Level 1 Inputs are unadjusted, quoted prices for identical assets or liabilities in active markets at the measurement date. Level 2 Inputs, other than quoted prices included in Level 1, that are observable for the asset or liability through corroboration with market data at the measurement date. Level 3 Unobservable inputs that reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. The Company’s financial instruments consist of cash and cash equivalents, marketable securities, accounts receivable, accounts payable and accrued expenses. The carrying values of its financial instruments approximate fair value based on their short-term nature. Cash, cash equivalents and marketable securities The Company obtained the fair value of its available-for-sale investments, which are not in active markets, from a third-party professional pricing service using quoted market prices for identical or comparable instruments, rather than direct observations of quoted prices in active markets. The Company's professional pricing service gathers observable inputs for all of its fixed income securities from a variety of industry data providers (e.g., large custodial institutions) and other third-party sources. Once the observable inputs are gathered, all data points are considered, and the fair value is determined. The Company validates the quoted market prices provided by its primary pricing service by comparing their assessment of the fair values against the fair values provided by its investment managers. The Company's investment managers use similar techniques to its professional pricing service to derive pricing as described above. As all significant inputs were observable, derived from observable information in the marketplace or supported by observable levels at which transactions are executed in the marketplace, the Company has classified its marketable 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 for cash, cash equivalents and marketable securities: As of March 31, 2021 Gross Cash Adjusted unrealized and cash Marketable cost gains (losses) Fair value equivalents securities Cash $ 48,706 $ — $ 48,706 $ 48,706 $ — Level 1: Money market accounts 171,308 — 171,308 171,308 — Level 2: Corporate bonds 5,477 (1 ) 5,476 — 5,476 U.S. Treasury securities 4,053 1 4,054 — 4,054 Agency mortgage-backed securities 3,603 3 3,606 — 3,606 Total $ 233,147 $ 3 $ 233,150 $ 220,014 $ 13,136 As of December 31, 2020 Gross Cash Adjusted unrealized and cash Marketable cost gains (losses) Fair value equivalents securities Cash $ 52,812 $ — $ 52,812 $ 52,812 $ — Level 1: Money market accounts 159,150 — 159,150 159,150 — Level 2: Corporate bonds 11,549 (1 ) 11,548 — 11,548 U.S. Treasury securities 4,107 — 4,107 — 4,107 Agency mortgage-backed securities 3,601 1 3,602 — 3,602 Total $ 231,219 $ — $ 231,219 $ 211,962 $ 19,257 Derivative instruments and hedging activities The Company transacts business in foreign currencies and has international sales and expenses denominated in foreign currencies, subjecting the Company to foreign currency risk. The Company has entered into foreign currency forward contracts, generally with maturities of twelve months or less, to reduce the volatility of cash flows primarily related to forecasted revenue denominated in certain foreign currencies. These contracts allow the Company to sell Euros in exchange for U.S. dollars at specified contract rates. Forward contracts are used to hedge forecasted sales over specific months. Changes in the fair value of these forward contracts designed as cash flow hedges are recorded as a component of accumulated other comprehensive income within stockholders’ equity and are recognized in the consolidated statements of comprehensive loss during the period which approximates the time the corresponding sales occur. The Company may also enter into foreign exchange contracts that are not designated as hedging instruments for financial accounting purposes. These contracts are generally entered into to offset the gains and losses on certain asset and liability balances until the expected time of repayment. Accordingly, any gains or losses resulting from changes in the fair value of the non-designated contracts are reported in other expense, net in the consolidated statements of comprehensive loss. The gains and losses on these contracts generally offset the gains and losses associated with the underlying foreign currency-denominated balances, which are also reported in other income (expense), net. The Company records the assets or liabilities associated with derivative instruments and hedging activities at fair value based on Level 2 inputs in other current assets or other current liabilities, respectively, in the consolidated balance sheet. The Company had a related receivable of $246 and payable of $863 as of March 31, 2021 and December 31, 2020, respectively. The Company documents the hedging relationship and its risk management objective and strategy for undertaking the hedge, the hedging instrument, the hedged transaction, the nature of the risk being hedged, how the hedging instrument’s effectiveness in offsetting the hedged risk will be assessed prospectively and retrospectively, and a description of the method used to measure ineffectiveness. The Company assesses hedge effectiveness and ineffectiveness at a minimum quarterly but may assess it monthly. For derivative instruments that are designed and qualify as part of a cash flow hedging relationship, the effective portion of the gain or loss on the derivative is reported in other comprehensive income and reclassified into earnings in the same periods during which the hedged transaction affects earnings. Gains and losses on the derivative representing either hedge ineffectiveness or hedge components excluded from the assessment of effectiveness are recognized in current period earnings. The Company will discontinue hedge accounting prospectively when it determines that the derivative is no longer effective in offsetting cash flows attributable to the hedge risk. The cash flow hedge is de-designated because a forecasted transaction is not probable of occurring, or management determines to remove the designation of the cash flow hedge. In all situations in which hedge accounting is discontinued and the derivative remains outstanding, the Company continues to carry the derivative at its fair value on the balance sheet and recognizes any subsequent changes in the fair value in earnings. When it is probable that a forecasted transaction will not occur, the Company will discontinue hedge accounting and recognize immediately in earnings gains and losses that were accumulated in other comprehensive income related to the hedging relationship. Accumulated other comprehensive income The components of accumulated other comprehensive income were as follows: Foreign Unrealized Unrealized Accumulated currency gains gains (losses) other translation on marketable on cash comprehensive adjustments securities flow hedges income Balance as of December 31, 2020 $ 1,128 $ — $ (653 ) $ 475 Other comprehensive income (loss) (457 ) 4 903 450 Balance as of March 31, 2021 $ 671 $ 4 $ 250 $ 925 Comprehensive income is the total net earnings and all other non-owner changes in equity. Except for net loss and unrealized gains and losses on cash flow hedges, the Company does not have any transactions or other economic events that qualify as other comprehensive income (loss). Earnout liability The Com pany has obligations to pay up to $31,400 in earnout payments in cash if certain future financial results are met. The earnout liability was valued using Level 3 inputs. The fair value of the earnout was determined by employing a Monte Carlo simulation in a risk-neutral framework. The underlying simulated variable includes recognized revenue. The recognized revenue volatility estimate was based on a study of historical asset volatility for a set of comparable public companies. The model includes other assumptions including the market price of risk, which was calculated as the weighted average cost of capital (WACC) less the long-term risk free rate. The earnout period for recognized revenue is each calendar year beginning with calendar year 2019 and ending on the calendar year in which the earnout consideration equals the earnout cap The following table provides quantitative information about Level 3 inputs for fair value measurement of the earnout liability as of March 31, 2021 and December 31, 2020. Significant increases or decreases in these inputs in isolation could result in a significant impact on our fair value measurement: As of As of Simulation input March 31, 2021 December 31, 2020 Revenue volatility 35.00 % 35.00 % WACC 12.50 % 12.00 % 20-year risk free rate 2.31 % 1.45 % Market price of risk 9.00 % 8.00 % The reconciliation of the earnout liability measured and carried at fair value on a recurring basis is as follows: Three months ended March 31, 2021 Balance at beginning of period $ 27,612 Change in fair value 265 Balance at end of period $ 27,877

Balance Sheet Components

Balance Sheet Components	3 Months Ended
	Mar. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	4. Balance sheet components Cash, cash equivalents and marketable securities The Company considers all short-term highly liquid investments with a maturity of three months or less to be cash equivalents. The Company’s marketable debt securities are classified and accounted for as available-for-sale. Cash equivalents are recorded at cost plus accrued interest, which is considered adjusted cost, and approximates fair value. Marketable debt securities are included in cash equivalents and marketable securities based on the maturity date of the security. Short-term investments are included in marketable securities in the current period presentation. The Company considers investments with maturities greater than three months, but less than one year, to be marketable securities. Investments are reported at fair value with realized and unrealized gains or losses reported in other income (expense), net. 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 other income (expense), net. Cash, cash equivalents, and marketable securities consist of the following: March 31, December 31, Cash and cash equivalents 2021 2020 Cash $ 48,706 $ 52,812 Money market accounts 171,308 159,150 Total cash and cash equivalents $ 220,014 $ 211,962 Marketable securities Corporate bonds $ 5,476 $ 11,548 U.S. Treasury securities 4,054 4,107 Agency mortgage-backed securities 3,606 3,602 Total marketable securities $ 13,136 $ 19,257 Accounts receivable and allowance for bad debts, returns, and adjustments Accounts receivable are customer obligations due under normal sales and rental terms. The Company performs credit evaluations of the customers’ financial condition and generally does not require collateral. The allowance for doubtful accounts is maintained at a level that, in management’s opinion, is adequate to absorb potential losses related to accounts receivable and is based upon the Company’s continuous evaluation of the collectability of outstanding balances. Management’s evaluation takes into consideration such factors as past bad debt experience, economic conditions and information about specific receivables. The Company’s evaluation also considers the age and composition of the outstanding amounts in determining their net realizable value. The allowance for doubtful accounts is based on estimates, and ultimate losses may vary from current estimates. As adjustments to these estimates become necessary, they are reported in general and administrative expense for sales revenue and as a reduction of rental revenue in the periods in which they become known. The allowance is increased by bad debt provisions, net of recoveries, and is reduced by direct write-offs. The Company generally does not allow returns from providers for reasons not covered under its standard warranty. Therefore, provision for returns applies primarily to direct-to-consumer sales. This reserve is calculated primarily based on actual historical return rates under the Company’s 30-day return program and is applied to the related sales revenue for the last month of the quarter reported. The Company also records an allowance for rental revenue adjustments which is recorded as a reduction of rental revenue and net rental accounts receivable balances. These adjustments result from contractual adjustments, 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 unbilled during the related period. When recording the allowance for doubtful accounts for sales revenue, 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 allowances for rental reserve adjustments and doubtful accounts, the rental revenue adjustments account (contra rental revenue account) is charged. As of March 31, 2021 and December 31, 2020, included in accounts receivable on the consolidated balance sheets were earned but unbilled receivables of $569 and $459, respectively. These balances reflect gross unbilled receivables prior to any allowances for adjustments and write-offs. The Company consistently applies its allowance estimation methodology from period-to-period. The Company’s best estimate is made on an accrual basis and adjusted in future periods as required. Any adjustments to the prior period estimates are included in the current period. As additional information becomes known, the Company adjusts its assumptions accordingly to change its estimate of the allowance. Gross accounts receivable balance concentrations by major category as of March 31, 2021 and December 31, 2020 were as follows: March 31, December 31, Gross accounts receivable 2021 2020 Rental (1) $ 5,701 $ 4,190 Business-to-business and other receivables (2) 34,055 26,717 Total gross accounts receivable $ 39,756 $ 30,907 Net accounts receivable (gross accounts receivable, net of allowances) balance concentrations by major category as of March 31, 2021 and December 31, 2020 were as follows: March 31, December 31, Net accounts receivable 2021 2020 Rental (1) $ 5,316 $ 3,794 Business-to-business and other receivables (2) 33,109 25,923 Total net accounts receivable $ 38,425 $ 29,717 (1) Rental includes Medicare, Medicaid/other government, private insurance and patient pay. (2) Business-to-business receivables included one customer with a gross accounts receivable balance of $8,102 and $7,044 as of March 31, 2021 and December 31, 2020, respectively. This customer received extended payment terms through a direct financing plan offered. The Company also has a credit insurance policy in place, which allocated up to $10,000 in coverage as of March 31, 2021 and as of December 31, 2020 for this customer with a $400 deductible and 10% retention. The following tables set forth the accounts receivable allowances as of March 31, 2021 and December 31, 2020: March 31, December 31, Allowances - accounts receivable 2021 2020 Doubtful accounts $ 21 $ 52 Rental revenue adjustments 385 396 Sales returns 925 742 Total allowances - accounts receivable $ 1,331 $ 1,190 Concentration of credit risk Financial instruments that potentially subject the Company to concentration of credit risk consist principally of cash, cash equivalents, marketable securities and accounts receivable. At times, cash account balances may be in excess of the amounts insured by the Federal Deposit Insurance Corporation (FDIC). However, management believes the risk of loss to be minimal. The Company performs periodic evaluations of the relative credit standing of these institutions and has not experienced any losses on its cash and cash equivalents to date. The Company has also entered into hedging relationships with a single counterparty to offset the forecasted Euro-based revenues. The credit risk has been reduced due to a net settlement arrangement whereby the Company is allowed to net settle transactions with a single net amount payable by one party to the other. Concentration of customers and vendors The Company primarily sells its products to traditional home medical equipment providers, distributors, and resellers in the United States and in foreign countries on a credit basis. The Company also sells its products direct-to-consumers on a primarily prepayment basis. One single customer represented more than 10% of the Company’s total revenue for the three months ended March 31, 2021 and for the three months ended March 31, 2020. Two customers each represented more than 10% of the Company’s net accounts receivable balance with accounts receivable balances of $10,434 and $8,102, respectively, as of March 31, 2021, and $8,417 and $7,044, respectively, as of December 31, 2020. 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 three months ended March 31, 2021, the Company’s three major vendors accounted for 19.9%, 10.8%, and 9.6%, respectively, of total raw material purchases. For the three months ended March 31, 2020, the Company’s three major vendors accounted for 23.6%, 15.2% and 9.4%, respectively, of total raw material purchases. A portion of revenue is earned from sales outside the United States. Approximately 79.3% and 68.7% of the non-U.S. revenue for the three months ended March 31, 2021 and March 31, 2020, respectively, were invoiced in Euros. A breakdown of the Company’s revenue from U.S. and non-U.S. sources for the three months ended March 31, 2021 and March 31, 2020, respectively, is as follows: Three months ended March 31, 2021 2020 U.S. revenue $ 71,212 $ 68,406 Non-U.S. revenue 15,720 20,083 Total revenue $ 86,932 $ 88,489 Inventories Inventories are stated at the lower of cost and net realizable value. Cost is determined using a standard cost method, including material, labor and manufacturing overhead, whereby the standard costs are updated at least quarterly to reflect approximate actual costs using the first-in, first-out (FIFO) method. The Company records adjustments at least quarterly to inventory for potentially excess, obsolete, slow-moving or impaired items. The Company recorded noncurrent inventor y related to inventories that are expected to be realized or consumed after one year of $ and $ as of March 3 1 , 20 2 1 and December 31, 20 20 , respectively. Noncurrent inventories are primarily related to raw materials purchased in bulk to support long - term expected repairs to reduce costs and are classified in other assets. During the three months ended March 3 1 , 202 1 and March 3 1 , 20 20 , $ and $ 368 , respectively, of inventory was transferred to rental equipment and was considered a noncash transaction in the production and purchase of rental equipment on the consolidated statements of cash flow. Inventories that are considered current consist of the following: March 31, December 31, 2021 2020 Raw materials and work-in-progress $ 24,210 $ 22,318 Finished goods 3,541 3,743 Less: reserves (1,357 ) (1,246 ) Inventories, net $ 26,394 $ 24,815 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 3-5 years Computer equipment and software 2-3 years Furniture and equipment 3-5 years Leasehold improvements Lesser of estimated useful life or remaining lease term Expenditures for additions, improvements and replacements are capitalized and depreciated to a salvage value of $0. Repair and maintenance costs on rental equipment are included in cost of rental revenue on the consolidated statements of comprehensive loss. Repair and maintenance expense, which includes labor, parts and freight, for rental equipment was $935 and $524 for the three months ended March 31, 2021 and March 31, 2020, respectively. Included within property and equipment is construction in process, primarily related to the design and engineering of tooling, jigs and other machinery. In addition, this item also includes computer software or development costs that have been purchased but have not completed the final configuration process for implementation into the Company’s systems. These items have not been placed in service; therefore, no depreciation or amortization was recognized for these items in the respective periods. Depreciation and amortization expense related to rental equipment and other property and equipment are summarized below for the three months ended March 31, 2021 and March 31, 2020, respectively. Three months ended March 31, 2021 2020 Rental equipment $ 1,888 $ 1,299 Other property and equipment 946 921 Total depreciation and amortization $ 2,834 $ 2,220 Property and equipment and rental equipment with associated accumulated depreciation is summarized below as of March 31, 2021 and December 31, 2020, respectively. March 31, December 31, Property and equipment 2021 2020 Rental equipment, net of allowances of $650 and $575, respectively $ 49,872 $ 46,953 Other property and equipment 28,642 27,071 Property and equipment 78,514 74,024 Accumulated depreciation Rental equipment 31,016 30,283 Other property and equipment 16,445 15,511 Accumulated depreciation 47,461 45,794 Property and equipment, net Rental equipment, net of allowances of $650 and $575, respectively 18,856 16,670 Other property and equipment 12,197 11,560 Property and equipment, net $ 31,053 $ 28,230 Long-lived assets The Company accounts for the impairment and disposition of long-lived assets in accordance with ASC 360 — Property, Plant, and Equipment Goodwill The changes in the carrying amount of goodwill for the three months ended March 31, 2021 were as follows: Balance as of December 31, 2020 $ 33,165 Translation adjustment (110 ) Balance as of March 31, 2021 $ 33,055 As of March 31, 2021, the Company had no accumulated impairment losses related to goodwill. Intangible assets There were no accumulated impairments losses related to the Company’s intangible assets as of March 31, 2021 and March 31, 2020. The following tables represent the changes in net carrying values of intangible assets as of the respective dates: Average estimated Gross useful lives carrying Accumulated March 31, 2021 (in years) amount amortization Net amount Technology 10 $ 77,700 $ 12,626 $ 65,074 Licenses 10 185 176 9 Patents and websites 5 4,488 3,197 1,291 Customer relationships 4 1,407 1,378 29 Commercials 2-3 759 605 154 Total $ 84,539 $ 17,982 $ 66,557 Average estimated Gross useful lives carrying Accumulated December 31, 2020 (in years) amount amortization Net amount Technology 10 $ 77,700 $ 10,684 $ 67,016 Licenses 10 185 174 11 Patents and websites 5 4,488 3,015 1,473 Customer relationships 4 1,474 1,351 123 Commercials 2-3 733 559 174 Total $ 84,580 $ 15,783 $ 68,797 Annual estimated amortization expense for each of the succeeding fiscal years is as follows: March 31, 2021 Remaining 9 months of 2021 $ 6,488 2022 8,431 2023 7,856 2024 7,832 2025 7,784 Thereafter 28,166 $ 66,557 Current liabilities Accounts payable and accrued expenses as of March 31, 2021 and December 31, 2020 consisted of the following: March 31, December 31, 2021 2020 Accounts payable $ 14,606 $ 12,520 Accrued inventory (in-transit and unvouchered receipts) and trade payables 9,666 9,023 Accrued litigation settlement — 8,000 Accrued purchasing card liability 4,051 2,468 Accrued franchise, sales and use taxes 482 449 Other accrued expenses 544 1,252 Accounts payable and accrued expenses $ 29,349 $ 33,712 Accrued payroll as of March 31, 2021 and December 31, 2020 consisted of the following: March 31, December 31, 2021 2020 Accrued bonuses $ 1,166 $ 4 Accrued wages and other payroll related items 4,873 3,796 Accrued vacation 2,970 2,642 Accrued employee stock purchase plan deductions 182 649 Accrued payroll $ 9,191 $ 7,091

Leases

Leases	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Leases	5. Leases The Company has entered into operating leases primarily for commercial buildings. These leases have terms which range from 2 years to 11 years, some of which include options to extend the leases for up to 5 years. There are no economic penalties for the Company to extend the lease, and it is not reasonably assured that the Company will exercise the extension options. Operating lease right-of-use assets and liabilities commencing after January 1, 2019 are recognized at commencement date based on the present value of lease payments over the lease term. The operating leases do not contain material residual value guarantees or material restrictive covenants. Rent expense, including short-term lease cost, was $987 and $751 for the three months ended March 31, 2021 and March 31, 2020, respectively. Information related to the Company's right-of-use assets and related operating lease liabilities were as follows: Three months ended March 31, 2021 2020 Cash paid for operating lease liabilities $ 554 $ 593 Operating lease cost 763 632 Non-cash right-of-use assets obtained in exchange for new operating lease obligations 9,340 2,809 Weighted-average remaining lease term 3.0 years 2.5 years Weighted-average discount rate 3.2 % 3.7 % Maturities of lease liabilities due in the 12-month period ending March 31, 2022 $ 2,878 2023 2,781 2024 2,799 2025 2,213 2026 1,564 Thereafter 8,452 20,687 Less imputed interest (1,777 ) Total lease liabilities $ 18,910 Operating lease liability - current $ 2,475 Operating lease liability - noncurrent $ 16,435 Total lease liabilities $ 18,910 As of March 31, 2021, the Company has additional operating leases for its corporate headquarters in California that has not yet commenced, with total minimum lease payments of $11,359. Lease payments for its corporate headquarters will increase annually by the lesser of the change, if any, in the Consumer Price Index of the Bureau of Labor Statistics of the U.S. Department of Labor or three and one-half percent (3.5%) at each annual adjustment date thereafter. The operating lease for its corporate headquarters is estimated to commence in the second quarter of 2021 with a lease term of approximately 10 years. The table above excludes lease payments that were not fixed at commencement or modification.

Earnings (loss) per Share

Earnings (loss) per Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Earnings per Share	6. Earnings (loss) per share Earnings (loss) per share (EPS) is computed in accordance with ASC 260 —Earnings per Share Basic earnings (loss) per share is calculated using the Company’s weighted-average outstanding common shares. Diluted earnings (loss) per share is calculated using the Company’s weighted-average outstanding common shares including the dilutive effect of stock awards as determined under the treasury stock method. The computation of EPS is as follows: Three months ended March 31, 2021 2020 Numerator—basic and diluted: Net loss $ (732 ) $ (1,589 ) Denominator: Weighted-average common shares - basic common stock (1) 22,181,394 21,916,365 Weighted-average common shares - diluted common stock 22,181,394 21,916,365 Net loss per share - basic common stock $ (0.03 ) $ (0.07 ) Net loss per share - diluted common stock (2) $ (0.03 ) $ (0.07 ) Denominator calculation from basic to diluted: Weighted-average common shares - basic common stock (1) 22,181,394 21,916,365 Stock options and other dilutive awards 341,716 327,891 Weighted-average common shares - diluted common stock 22,523,110 22,244,256 Shares excluded from diluted weighted-average shares: Stock options 64,498 81,220 Restricted stock units and restricted stock awards 308,787 293,236 Shares excluded from diluted weighted-average shares 373,285 374,456 (1) Unvested restricted stock units and restricted stock awards are not included as shares outstanding in the calculation of basic earnings per share. Vested restricted stock units and restricted stock awards are included in basic earnings per share if all vesting and performance criteria have been met. Performance-based restricted stock units and restricted stock awards are included in the number of shares used to calculate diluted earnings per share as long as all applicable performance criteria are met, and their effect is dilutive. Restricted stock awards are eligible to receive all dividends declared on the Company’s common shares during the vesting period; however, such dividends are not paid until the restrictions lapse . (2) Due to a net loss for the three months ended March 31, 2021 and March 31, 2020, diluted loss per share is the same as basic.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	7. Income taxes The Company accounts for income taxes in accordance with ASC 740 — Income Taxes The Company accounts for uncertainties in income taxes in accordance with ASC 740-10 — Accounting for Uncertainty in Income Taxes The Company recognizes interest and penalties on taxes, if any, within its income tax provision (benefit) on its consolidated statements of comprehensive loss.

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Stockholders' Equity	8. Stockholders’ equity The Company has a 2002 Stock Incentive Plan (2002 Plan) as amended, under which the Company granted options to purchase shares of its common stock. As of March 31, 2021, there are no remaining options to purchase shares of common stock under the 2002 Plan. The 2002 Plan was terminated in March 2012 in connection with the adoption of the 2012 Plan, and, accordingly, no new options are available for issuance under this plan. The 2002 Plan continues to govern outstanding awards granted thereunder. The Company has a 2012 Equity Incentive Plan (2012 Plan) under which the Company granted options to purchase shares of its common stock. As of March 31, 2021, options to purchase 119,840 shares of common stock remained outstanding under the 2012 Plan. The 2012 Plan was terminated in connection with the Company’s initial public offering in February 2014, and accordingly, no new options are available for issuance under this plan. The 2012 Plan continues to govern outstanding awards granted thereunder. The Company has a 2014 Equity Incentive Plan (2014 Plan) that provides for the grant of incentive stock options, within the meaning of Section 422 of the Internal Revenue Code, to the Company’s employees and any parent and subsidiary corporation’s employees, and for the grant of nonstatutory stock options, restricted stock, restricted stock units, restricted stock awards, stock appreciation rights, performance units and performance shares to its employees, directors and consultants and its parent and subsidiary corporations’ employees and consultants. As of March 31, 2021, awards with respect to 1,146,603 shares of the Company’s common stock were outstanding, and 1,380,980 shares of common stock remained available for issuance under the 2014 Plan. The shares available for issuance under the 2014 Plan will be increased by any shares returned to the 2002 Plan, 2012 Plan and the 2014 Plan as a result of expiration or termination of awards (provided that the maximum number of shares that may be added to the 2014 Plan pursuant to such previously granted awards under the 2002 Plan and 2012 Plan is 2,328,569 shares). The number of shares available for issuance under the 2014 Plan also is increased annually on the first day of each fiscal year by an amount equal to the least of: • 895,346 shares; • 4% of the outstanding shares of common stock as of the last day of the Company’s immediately preceding fiscal year; or • such other amount as the Company’s board of directors may determine. For 2021, no additional shares were added to the 2014 Plan share reserve pursuant to the provision described above. Stock options Options typically expire between seven and ten years from the date of grant and vest over one to four year terms. Options have been granted to employees, directors and consultants of the Company, as determined by the board of directors, at the deemed fair market value of the shares underlying the options at the date of grant. The activity for stock options under the Company’s stock plans for the three months ended March 31, 2021 is as follows: Remaining weighted- Weighted- average Per share average contractual average Price per exercise terms intrinsic Options share price (in years) value Outstanding as of December 31, 2020 955,479 $0.75-$83.30 $ 35.49 1.85 $ 11.81 Exercised (205,753 ) 0.75-46.66 18.79 Forfeited — — — Outstanding as of March 31, 2021 749,726 0.81-83.30 40.07 1.96 15.09 Vested and exercisable as of March 31, 2021 749,726 0.81-83.30 40.07 1.96 15.09 Vested and expected to vest as of March 31, 2021 749,726 $0.81-$83.30 $ 40.07 1.96 $ 15.09 The total intrinsic value of options exercised during the three months ended March 31, 2021 and March 31, 2020 was $6,504 and $239, respectively. As of March 31, 2021, all stock-based compensation expense for options granted under the Plans was recognized. Stock incentive awards The Company grants restricted stock units (RSUs) and restricted stock awards (RSAs) under the 2014 Plan (Stock Awards). The Stock Awards vest either based solely on the satisfaction of time-based service conditions or on the satisfaction of time-based service conditions combined with performance criteria. Stock Awards are subject to forfeiture if the holder’s services to the Company terminate before vesting. Stock Awards granted with only time-based service vesting conditions generally vest over a four-year three-year Stock Awards activity for the three months ended March 31, 2021 is summarized below: Weighted- average grant Performance date fair and value Restricted stock units Time-based time-based Total per share Unvested restricted stock units as of December 31, 2020 245,462 88,458 333,920 $ 49.29 Granted 171,340 88,902 260,242 53.14 Vested (39,293 ) — (39,293 ) 52.58 Forfeited/canceled (3,742 ) (29,485 ) (33,227 ) 48.08 Unvested restricted stock units as of March 31, 2021 (1) 373,767 147,875 521,642 $ 50.95 Unvested and expected to vest restricted stock units outstanding as of March 31, 2021 411,867 $ 51.09 Weighted- average grant Performance date fair and value Restricted stock awards Time-based time-based Total per share Unvested restricted stock awards outstanding as of December 31, 2020 42,076 33,355 75,431 $ 93.96 Vested (5,609 ) — (5,609 ) 90.24 Forfeited/canceled — (21,510 ) (21,510 ) 118.41 Unvested restricted stock awards outstanding as of March 31, 2021 (1) 36,467 11,845 48,312 $ 86.52 Unvested and expected to vest restricted stock awards outstanding as of March 31, 2021 38,978 $ 85.32 (1) Outstanding restricted stock units and restricted stock awards are based on the maximum payout of the targeted number of shares. As of March 31, 2021, the unrecognized compensation cost related to unvested employee restricted stock units and restricted stock awards was $21,694, excluding estimated forfeitures. This amount is expected to be recognized over a weighted-average period of 2.8 years. Employee stock purchase plan The Company’s 2014 Employee Stock Purchase Plan (ESPP) provides for the grant to all eligible employees an option to purchase stock under the ESPP, within the meaning Section 423 of the Internal Revenue Code. The ESPP permits participants to purchase common stock through payroll deductions of up to 15% of their eligible compensation, which includes a participant’s base straight time gross earnings, incentive compensation, bonuses, overtime and shift premium, but exclusive of payments for equity compensation and other similar compensation. A participant may purchase a maximum of 1,500 shares during a purchase period. Amounts deducted and accumulated by the participant are used to purchase shares of the Company’s common stock at the end of each six-month period. The purchase price of the shares will be 85% of the lower of the fair market value of the Company’s common stock on the first trading day of each offering period or on the exercise date. The offering periods are currently approximately six months in length beginning on the first business day on or after March 1 and September 1 of each year and ending on the first business day on or after September 1 and March 1 approximately six months later. As of March 31, 2021, a total of 592,466 shares of common stock were available for sale pursuant to the ESPP. The number of shares available for sale under the ESPP is increased annually on the first day of each fiscal year by an amount equal to the least of: • 179,069 shares; • 1.5% of the outstanding shares of the Company’s common stock on the last day of the Company’s immediately preceding fiscal year; or • such other amount as may be determined by the administrator. For 2021, no additional shares were added to the ESPP share reserve pursuant to the provision described above. Stock-based compensation Stock-based compensation expense recognized for the three months ended March 31, 2021 and March 31, 2020, was as follows: Three months ended March 31, 2021 2020 Stock-based compensation expense by type of award: Stock option plan awards $ — $ 525 Restricted stock units and restricted stock awards 2,330 2,083 Employee stock purchase plan 186 176 Total stock-based compensation expense $ 2,516 $ 2,784 Employee stock-based compensation expense was calculated based on awards of stock options, restricted stock units and restricted stock awards ultimately expected to vest based on the Company’s historical award cancellations. ASC 718 – Compensation-Stock Compensation For the three months ended March 31, 2021 and March 31, 2020, respectively, stock-based compensation expense recognized under ASC 718, included in cost of revenue, research and development expense, sales and marketing expense, and general and administrative expense was as follows: Three months ended March 31, 2021 2020 Cost of revenue $ 238 $ 229 Research and development 298 320 Sales and marketing 612 612 General and administrative 1,368 1,623 Total stock-based compensation expense $ 2,516 $ 2,784 401(k) retirement savings plan The Company maintains a 401(k) retirement savings plan for the benefit of eligible employees. Under the terms of this plan, eligible employees are able to make contributions to the plan on a tax-deferred basis. The Company matched employees’ contributions from January 1, 2017 through June 30, 2020. The Company suspended its 401(k) match, effective July 1, 2020. The Company contributed $0 and $252, net of forfeitures, to the 401(k) plan for the three months ended March 31, 2021 and March 31, 2020, respectively.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and contingencies Non-cancelable contractual obligations The Company enters into non-cancelable contractual obligations for software licenses and maintenance agreements. As of March 31, 2021, the minimum aggregate payments due under specified non-cancelable contractual obligations are summarized as follows: Non-cancelable contractual obligations Remaining 9 months of 2021 $ 313 2022 — 2023 — 2024 — 2025 — Thereafter — $ 313 Purchase obligations The Company had approximately $64,400 of outstanding purchase orders due within one year with its outside vendors and suppliers as of March 31, 2021. Warranty obligations The following table identifies the changes in the Company’s aggregate product warranty liabilities for the three and twelve-month periods ended March 31, 2021 and December 31, 2020, respectively: March 31, December 31, 2021 2020 Product warranty liability at beginning of period $ 14,394 $ 12,571 Accruals for warranties issued 2,966 9,462 Adjustments related to preexisting warranties (including changes in estimates) (330 ) (754 ) Settlements made (in cash or in kind) (2,116 ) (6,885 ) Product warranty liability at end of period $ 14,914 $ 14,394 Contract liabilities Contract liabilities primarily consist of deferred revenue related to lifetime warranties on direct-to-consumer sales revenue when payments are received in advance of services performed under the contract. The contract with the customer states the final terms of the sale, including the description, quantity, and price of each product or service purchase. The increase in deferred revenue related to lifetime warranties for the three months ended March 31, 2021 was primarily driven by $1,604 of payments received in advance of satisfying performance obligations, partially offset by $1,375 of revenue recognized that was included in the deferred revenue balances as of December 31, 2020. Deferred revenue related to lifetime warranties was $17,307 and $17,078 as of March 31, 2021 and December 31, 2020, respectively, and is classified within deferred revenue – current and deferred revenue – noncurrent in the consolidated balance sheet. Legislation and HIPAA The healthcare industry is subject to numerous laws and regulations of federal, state and local governments. These laws and regulations include, but are not necessarily limited to, matters such as licensure, accreditation, government healthcare program participation requirements, reimbursement for patient services, and Medicare and Medicaid fraud and abuse. Government activity has continued with respect to investigations and allegations concerning possible violations of fraud and abuse statutes and regulations by healthcare providers. Violations of these laws and regulations could result in exclusion from government healthcare programs together with the imposition of significant fines and penalties, as well as significant repayments for patient services previously billed. The Company believes that it is in compliance in all material respects with applicable fraud and abuse regulations and other applicable government laws and regulations. Compliance with such laws and regulations can be subject to future government review and interpretation as well as regulatory actions unknown or unasserted at this time. The Health Insurance Portability and Accountability Act of 1996 (HIPAA) was enacted to en sure health insurance portability, reduce healthcare fraud and abuse, guarantee security and privacy of health information, and enforce standards for health information. The Health Information Technology for Economic and Clinical Health Act (HITECH Act) , in part, imposes notification requirements of certain security breaches relating to protected health information. The Company believes that it complies in all material respects with the provisions of those regulations that are applicable to the Company’s business. Legal proceedings Securities class action and derivative lawsuits On March 6, 2019, plaintiff William Fabbri filed a lawsuit against Inogen, Scott Wilkinson, and Alison Bauerlein, in the United States District Court for the Central District of California on behalf of a purported class of purchasers of the Company’s securities. On March 21, 2019, plaintiff Steven Friedland filed a substantially similar lawsuit against the same defendants in the same court. On May 20, 2019, the court issued an order consolidating the two lawsuits under the name In re Inogen, Inc. Sec. Litig., O On June 26, 2019, plaintiff Twana Brown filed a shareholder derivative lawsuit against Inogen, Scott Wilkinson, Alison Bauerlein, Benjamin Anderson-Ray, Scott Beardsley, R. Scott Greer, Raymond Huggenberger, Heath Lukatch, Loren McFarland, and Heather Rider in the United States District Court for the Central District of California. The complaint purports to bring claims on behalf of Inogen against the individual defendants for breaches of their fiduciary duties as directors and/or officers of Inogen, unjust enrichment, waste of corporate assets and violations of section 14(a) of the Securities Exchange Act of 1934, as amended. The complaint generally alleges similar claims to the securities class action. The complaint seeks compensatory damages and restitution in an unspecified amount, changes to the Company’s corporate governance and internal procedures, costs and expenses, including attorneys’ fees and expert fees, and such other relief as the court deems proper. On August 5, 2019, the court issued an order staying the derivative action pending the resolution of the motion to dismiss stage in In re Inogen, Inc. Sec. Litig Between October 7, 2019 and October 31, 2019, three additional shareholder derivative complaints On January 13, 2020, the court consolidated the four derivative lawsuits before it under the name In re Inogen, Inc. S’holder Deriv. Litig. , Lead Case No. 2:19-cv-5568-FMO-AGR and ordered that the consolidated action be stayed pending the resolution of the motion to dismiss stage in In re Inogen, Inc., Sec. Litig. On September 13, 2019, plaintiff Dustin Weller filed a shareholder derivative lawsuit against Inogen, Scott Wilkinson, Alison Bauerlein, Benjamin Anderson-Ray, Scott Beardsley, R. Scott Greer, Raymond Huggenberger, Heath Lukatch, Loren McFarland, and Heather Rider in the United States District Court for the District of Delaware captioned Weller v. Wilkinson, et al. , No. 1:19-cv-01723-MN. On October 17, 2019, plaintiff Sharokh Soltanipour filed a shareholder derivative lawsuit against the same defendants in the same court, captioned Soltanipour v. Wilkinson, et al. , No. 1:19-cv-1968-MN. The complaints generally allege similar claims to those in In re Inogen, Inc., S’holder Deriv. Litig. The complaints purport to bring claims on behalf of Inogen for breach of fiduciary duty, unjust enrichment, waste of corporate assets, abuse of control, gross mismanagement, insider selling and misappropriation of information, violations of section 14(a) of the Securities Exchange Act of 1934, as amended, and for contribution from certain of the individual defendants. The complaints seek compensatory damages in unspecified amounts, changes to the Company’s corporate governance and internal procedures, return of compensation, disgorgement of profits from sale of stock, costs and expenses, including attorneys’ fees and expert fees, and such other relief as the court deems proper. On May 15, 2020, the court consolidated the two derivative lawsuits before it under the name In re Inogen, Inc. S’holder Deriv. Litig. , Lead Case No. 1:19-cv-01723-MN-JLH. On July 8, 2020, the court ordered that the consolidated action be stayed pending the resolution of the motion to dismiss in the securities class action, In re Inogen, Inc., Sec. Litig . Department of Health and Human Services and the Centers for Medicare and Medicaid Services lawsuit On September 21, 2020, Inogen filed a lawsuit against defendants, Alex M. Azar, Secretary of the Department of Health and Human Services (HHS), in his official capacity, Seema Verma, Administrator of the Centers for Medicare and Medicaid Services (CMS), in her official capacity and Palmetto GBA, LLC. The lawsuit seeks to invalidate the defendants’ arbitrary and capricious decision to retract a valid HCPCS code to Inogen’s Tidal Assist ® ® , et seq. Other litigation In addition to the lawsuits discussed above, the Company is party to various legal proceedings arising in the normal course of business. The Company carries insurance, subject to specified deductibles under the policies, to protect against losses from certain types of legal claims. At this time, the Company does not anticipate that any of these other proceedings arising in the normal course of business will have a material adverse effect on the Company’s business. Regardless of the outcome, litigation can have an adverse impact on the Company because of defense and settlement costs, diversion of management resources, and other factors.

Foreign Currency Exchange Contr

Foreign Currency Exchange Contracts and Hedging	3 Months Ended
	Mar. 31, 2021
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Foreign currency exchange contracts and hedging	10. Foreign currency exchange contracts and hedging As of March 31, 2021 and March 31, 2020, the Company’s total non-designated and designated derivative contracts had notional amounts totaling approximately $1,704 and $20,491, respectively, and $3,885 and $23,788, respectively. These contracts were comprised of offsetting contracts with the same counterparty, each expires within one to twelve months. During the three months ended March 31, 2021 and March 31, 2020, these contracts had, net of tax, unrealized gains of $903 and $673, respectively. The nonperformance risk of the Company and the counterparty did not have a material impact on the fair value of the derivatives. During the three months ended March 31, 2021 and March 31, 2020, there were no ineffective portions relating to these hedges and the hedges remained effective through their respective settlement dates. As of March 31, 2021, the Company had twenty-two designated hedges and two non-designated hedges. As of March 31, 2020, the Company had eight designated hedges and one non-designated hedge.

Basis of Presentation and Sum_2

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Consolidation	Basis of consolidation The consolidated financial statements include the accounts of Inogen, Inc. and its wholly owned subsidiary. All intercompany balances and transactions have been eliminated.
Use of Estimates	Use of estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Management bases these estimates and assumptions upon historical experience, existing and known circumstances, authoritative accounting pronouncements and other factors that management believes to be reasonable. Significant areas requiring the use of management estimates relate to revenue recognition, warranty reserves and expense, determining the stand-alone selling price (SSP) and service period of performance obligations, rental asset valuations and write-downs, accounts receivable allowances for bad debts, returns and adjustments, impairment of long-lived assets, stock -based compensation expense, income ta xes , fair value of acquired intangible assets and goodwill and fair value of earnout liabilities . Actual results could differ from these estimates.
Recently Adopted Accounting Pronouncements	Recently adopted accounting pronouncements In December 2019, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. The new guidance simplifies the accounting for income taxes by removing certain exceptions to the general principles in Topic 740. The new guidance also improves consistent application of and simplifies U.S. GAAP for other areas of Topic 740 by clarifying and amending the existing guidance
Business Segments	Business segments The Company operates and reports in only one operating and reportable segment – development, manufacturing, marketing, sales, and rental of respiratory products. Management reports financial information on a consolidated basis to the Company’s chief operating decision maker.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Summary of Fair Value Assets Measured on Recurring Basis for Cash, Cash Equivalents and Marketable Securities	The following table summarizes fair value measurements by level for the assets measured at fair value on a recurring basis for cash, cash equivalents and marketable securities: As of March 31, 2021 Gross Cash Adjusted unrealized and cash Marketable cost gains (losses) Fair value equivalents securities Cash $ 48,706 $ — $ 48,706 $ 48,706 $ — Level 1: Money market accounts 171,308 — 171,308 171,308 — Level 2: Corporate bonds 5,477 (1 ) 5,476 — 5,476 U.S. Treasury securities 4,053 1 4,054 — 4,054 Agency mortgage-backed securities 3,603 3 3,606 — 3,606 Total $ 233,147 $ 3 $ 233,150 $ 220,014 $ 13,136 As of December 31, 2020 Gross Cash Adjusted unrealized and cash Marketable cost gains (losses) Fair value equivalents securities Cash $ 52,812 $ — $ 52,812 $ 52,812 $ — Level 1: Money market accounts 159,150 — 159,150 159,150 — Level 2: Corporate bonds 11,549 (1 ) 11,548 — 11,548 U.S. Treasury securities 4,107 — 4,107 — 4,107 Agency mortgage-backed securities 3,601 1 3,602 — 3,602 Total $ 231,219 $ — $ 231,219 $ 211,962 $ 19,257
Summary of Components of Accumulated Other Comprehensive Income (Loss)	The components of accumulated other comprehensive income were as follows: Foreign Unrealized Unrealized Accumulated currency gains gains (losses) other translation on marketable on cash comprehensive adjustments securities flow hedges income Balance as of December 31, 2020 $ 1,128 $ — $ (653 ) $ 475 Other comprehensive income (loss) (457 ) 4 903 450 Balance as of March 31, 2021 $ 671 $ 4 $ 250 $ 925
Summary of Quantitative Information about Level 3 Inputs for Fair Value Measurement of Earnout Liability	The following table provides quantitative information about Level 3 inputs for fair value measurement of the earnout liability as of March 31, 2021 and December 31, 2020. Significant increases or decreases in these inputs in isolation could result in a significant impact on our fair value measurement: As of As of Simulation input March 31, 2021 December 31, 2020 Revenue volatility 35.00 % 35.00 % WACC 12.50 % 12.00 % 20-year risk free rate 2.31 % 1.45 % Market price of risk 9.00 % 8.00 %
Summary of Reconciliation of Earnout Liability Measured and Carried Fair Value on a Recurring Basis	The reconciliation of the earnout liability measured and carried at fair value on a recurring basis is as follows: Three months ended March 31, 2021 Balance at beginning of period $ 27,612 Change in fair value 265 Balance at end of period $ 27,877

Balance Sheet Components (Table

Balance Sheet Components (Tables)	3 Months Ended
	Mar. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Summary of Cash, Cash Equivalents and Short-term Investments	Cash, cash equivalents, and marketable securities consist of the following: March 31, December 31, Cash and cash equivalents 2021 2020 Cash $ 48,706 $ 52,812 Money market accounts 171,308 159,150 Total cash and cash equivalents $ 220,014 $ 211,962 Marketable securities Corporate bonds $ 5,476 $ 11,548 U.S. Treasury securities 4,054 4,107 Agency mortgage-backed securities 3,606 3,602 Total marketable securities $ 13,136 $ 19,257
Schedule of Gross Accounts Receivable Balance Concentrations by Major Category	Gross accounts receivable balance concentrations by major category as of March 31, 2021 and December 31, 2020 were as follows: March 31, December 31, Gross accounts receivable 2021 2020 Rental (1) $ 5,701 $ 4,190 Business-to-business and other receivables (2) 34,055 26,717 Total gross accounts receivable $ 39,756 $ 30,907 (1) Rental includes Medicare, Medicaid/other government, private insurance and patient pay. (2) Business-to-business receivables included one customer with a gross accounts receivable balance of $8,102 and $7,044 as of March 31, 2021 and December 31, 2020, respectively. This customer received extended payment terms through a direct financing plan offered. The Company also has a credit insurance policy in place, which allocated up to $10,000 in coverage as of March 31, 2021 and as of December 31, 2020 for this customer with a $400 deductible and 10% retention.
Schedule of Net Accounts Receivable Balance Concentrations by Major Category	Net accounts receivable (gross accounts receivable, net of allowances) balance concentrations by major category as of March 31, 2021 and December 31, 2020 were as follows: March 31, December 31, Net accounts receivable 2021 2020 Rental (1) $ 5,316 $ 3,794 Business-to-business and other receivables (2) 33,109 25,923 Total net accounts receivable $ 38,425 $ 29,717 (1) Rental includes Medicare, Medicaid/other government, private insurance and patient pay. (2) Business-to-business receivables included one customer with a gross accounts receivable balance of $8,102 and $7,044 as of March 31, 2021 and December 31, 2020, respectively. This customer received extended payment terms through a direct financing plan offered. The Company also has a credit insurance policy in place, which allocated up to $10,000 in coverage as of March 31, 2021 and as of December 31, 2020 for this customer with a $400 deductible and 10% retention.
Schedule of Allowances for Accounts Receivable	The following tables set forth the accounts receivable allowances as of March 31, 2021 and December 31, 2020: March 31, December 31, Allowances - accounts receivable 2021 2020 Doubtful accounts $ 21 $ 52 Rental revenue adjustments 385 396 Sales returns 925 742 Total allowances - accounts receivable $ 1,331 $ 1,190
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 79.3% and 68.7% of the non-U.S. revenue for the three months ended March 31, 2021 and March 31, 2020, respectively, were invoiced in Euros. A breakdown of the Company’s revenue from U.S. and non-U.S. sources for the three months ended March 31, 2021 and March 31, 2020, respectively, is as follows: Three months ended March 31, 2021 2020 U.S. revenue $ 71,212 $ 68,406 Non-U.S. revenue 15,720 20,083 Total revenue $ 86,932 $ 88,489
Schedule of Inventories	Inventories that are considered current consist of the following: March 31, December 31, 2021 2020 Raw materials and work-in-progress $ 24,210 $ 22,318 Finished goods 3,541 3,743 Less: reserves (1,357 ) (1,246 ) Inventories, net $ 26,394 $ 24,815
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 3-5 years Computer equipment and software 2-3 years Furniture and equipment 3-5 years Leasehold improvements Lesser of estimated useful life or remaining lease term
Summary of Depreciation and Amortization Expense of Rental Equipment and Other Property and Equipment	Depreciation and amortization expense related to rental equipment and other property and equipment are summarized below for the three months ended March 31, 2021 and March 31, 2020, respectively. Three months ended March 31, 2021 2020 Rental equipment $ 1,888 $ 1,299 Other property and equipment 946 921 Total depreciation and amortization $ 2,834 $ 2,220
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 as of March 31, 2021 and December 31, 2020, respectively. March 31, December 31, Property and equipment 2021 2020 Rental equipment, net of allowances of $650 and $575, respectively $ 49,872 $ 46,953 Other property and equipment 28,642 27,071 Property and equipment 78,514 74,024 Accumulated depreciation Rental equipment 31,016 30,283 Other property and equipment 16,445 15,511 Accumulated depreciation 47,461 45,794 Property and equipment, net Rental equipment, net of allowances of $650 and $575, respectively 18,856 16,670 Other property and equipment 12,197 11,560 Property and equipment, net $ 31,053 $ 28,230
Schedule of Changes in Carrying Amount of Goodwill	The changes in the carrying amount of goodwill for the three months ended March 31, 2021 were as follows: Balance as of December 31, 2020 $ 33,165 Translation adjustment (110 ) Balance as of March 31, 2021 $ 33,055
Summary of Changes in Net Carrying Values of Intangible Assets	The following tables represent the changes in net carrying values of intangible assets as of the respective dates: Average estimated Gross useful lives carrying Accumulated March 31, 2021 (in years) amount amortization Net amount Technology 10 $ 77,700 $ 12,626 $ 65,074 Licenses 10 185 176 9 Patents and websites 5 4,488 3,197 1,291 Customer relationships 4 1,407 1,378 29 Commercials 2-3 759 605 154 Total $ 84,539 $ 17,982 $ 66,557 Average estimated Gross useful lives carrying Accumulated December 31, 2020 (in years) amount amortization Net amount Technology 10 $ 77,700 $ 10,684 $ 67,016 Licenses 10 185 174 11 Patents and websites 5 4,488 3,015 1,473 Customer relationships 4 1,474 1,351 123 Commercials 2-3 733 559 174 Total $ 84,580 $ 15,783 $ 68,797
Schedule of Annual Estimated Amortization Expense	Annual estimated amortization expense for each of the succeeding fiscal years is as follows: March 31, 2021 Remaining 9 months of 2021 $ 6,488 2022 8,431 2023 7,856 2024 7,832 2025 7,784 Thereafter 28,166 $ 66,557
Schedule of Accounts Payable and Accrued Expenses	Accounts payable and accrued expenses as of March 31, 2021 and December 31, 2020 consisted of the following: March 31, December 31, 2021 2020 Accounts payable $ 14,606 $ 12,520 Accrued inventory (in-transit and unvouchered receipts) and trade payables 9,666 9,023 Accrued litigation settlement — 8,000 Accrued purchasing card liability 4,051 2,468 Accrued franchise, sales and use taxes 482 449 Other accrued expenses 544 1,252 Accounts payable and accrued expenses $ 29,349 $ 33,712
Schedule of Accrued Payroll	Accrued payroll as of March 31, 2021 and December 31, 2020 consisted of the following: March 31, December 31, 2021 2020 Accrued bonuses $ 1,166 $ 4 Accrued wages and other payroll related items 4,873 3,796 Accrued vacation 2,970 2,642 Accrued employee stock purchase plan deductions 182 649 Accrued payroll $ 9,191 $ 7,091

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Schedule of Right-of-Use Assets and Operating Lease Liabilities	Information related to the Company's right-of-use assets and related operating lease liabilities were as follows: Three months ended March 31, 2021 2020 Cash paid for operating lease liabilities $ 554 $ 593 Operating lease cost 763 632 Non-cash right-of-use assets obtained in exchange for new operating lease obligations 9,340 2,809 Weighted-average remaining lease term 3.0 years 2.5 years Weighted-average discount rate 3.2 % 3.7 %
Schedule of Maturities of Lease Liabilities	Maturities of lease liabilities due in the 12-month period ending March 31, 2022 $ 2,878 2023 2,781 2024 2,799 2025 2,213 2026 1,564 Thereafter 8,452 20,687 Less imputed interest (1,777 ) Total lease liabilities $ 18,910 Operating lease liability - current $ 2,475 Operating lease liability - noncurrent $ 16,435 Total lease liabilities $ 18,910

Earnings (loss) per Share (Tabl

Earnings (loss) per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Computation of Earnings Per Share	The computation of EPS is as follows: Three months ended March 31, 2021 2020 Numerator—basic and diluted: Net loss $ (732 ) $ (1,589 ) Denominator: Weighted-average common shares - basic common stock (1) 22,181,394 21,916,365 Weighted-average common shares - diluted common stock 22,181,394 21,916,365 Net loss per share - basic common stock $ (0.03 ) $ (0.07 ) Net loss per share - diluted common stock (2) $ (0.03 ) $ (0.07 ) Denominator calculation from basic to diluted: Weighted-average common shares - basic common stock (1) 22,181,394 21,916,365 Stock options and other dilutive awards 341,716 327,891 Weighted-average common shares - diluted common stock 22,523,110 22,244,256 Shares excluded from diluted weighted-average shares: Stock options 64,498 81,220 Restricted stock units and restricted stock awards 308,787 293,236 Shares excluded from diluted weighted-average shares 373,285 374,456 (1) Unvested restricted stock units and restricted stock awards are not included as shares outstanding in the calculation of basic earnings per share. Vested restricted stock units and restricted stock awards are included in basic earnings per share if all vesting and performance criteria have been met. Performance-based restricted stock units and restricted stock awards are included in the number of shares used to calculate diluted earnings per share as long as all applicable performance criteria are met, and their effect is dilutive. Restricted stock awards are eligible to receive all dividends declared on the Company’s common shares during the vesting period; however, such dividends are not paid until the restrictions lapse . (2) Due to a net loss for the three months ended March 31, 2021 and March 31, 2020, diluted loss per share is the same as basic.

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Summary of Stock Options Activity	The activity for stock options under the Company’s stock plans for the three months ended March 31, 2021 is as follows: Remaining weighted- Weighted- average Per share average contractual average Price per exercise terms intrinsic Options share price (in years) value Outstanding as of December 31, 2020 955,479 $0.75-$83.30 $ 35.49 1.85 $ 11.81 Exercised (205,753 ) 0.75-46.66 18.79 Forfeited — — — Outstanding as of March 31, 2021 749,726 0.81-83.30 40.07 1.96 15.09 Vested and exercisable as of March 31, 2021 749,726 0.81-83.30 40.07 1.96 15.09 Vested and expected to vest as of March 31, 2021 749,726 $0.81-$83.30 $ 40.07 1.96 $ 15.09
Summary of Restricted Stock Activity	Stock Awards activity for the three months ended March 31, 2021 is summarized below: Weighted- average grant Performance date fair and value Restricted stock units Time-based time-based Total per share Unvested restricted stock units as of December 31, 2020 245,462 88,458 333,920 $ 49.29 Granted 171,340 88,902 260,242 53.14 Vested (39,293 ) — (39,293 ) 52.58 Forfeited/canceled (3,742 ) (29,485 ) (33,227 ) 48.08 Unvested restricted stock units as of March 31, 2021 (1) 373,767 147,875 521,642 $ 50.95 Unvested and expected to vest restricted stock units outstanding as of March 31, 2021 411,867 $ 51.09 Weighted- average grant Performance date fair and value Restricted stock awards Time-based time-based Total per share Unvested restricted stock awards outstanding as of December 31, 2020 42,076 33,355 75,431 $ 93.96 Vested (5,609 ) — (5,609 ) 90.24 Forfeited/canceled — (21,510 ) (21,510 ) 118.41 Unvested restricted stock awards outstanding as of March 31, 2021 (1) 36,467 11,845 48,312 $ 86.52 Unvested and expected to vest restricted stock awards outstanding as of March 31, 2021 38,978 $ 85.32 (1) Outstanding restricted stock units and restricted stock awards are based on the maximum payout of the targeted number of shares.
Summary of Stock-based Compensation Expense	Stock-based compensation Stock-based compensation expense recognized for the three months ended March 31, 2021 and March 31, 2020, was as follows: Three months ended March 31, 2021 2020 Stock-based compensation expense by type of award: Stock option plan awards $ — $ 525 Restricted stock units and restricted stock awards 2,330 2,083 Employee stock purchase plan 186 176 Total stock-based compensation expense $ 2,516 $ 2,784 For the three months ended March 31, 2021 and March 31, 2020, respectively, stock-based compensation expense recognized under ASC 718, included in cost of revenue, research and development expense, sales and marketing expense, and general and administrative expense was as follows: Three months ended March 31, 2021 2020 Cost of revenue $ 238 $ 229 Research and development 298 320 Sales and marketing 612 612 General and administrative 1,368 1,623 Total stock-based compensation expense $ 2,516 $ 2,784

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Minimum Aggregate Payments Due under Operating Leases and Specified Non-Cancelable Contractual Obligations Consist of Software License and Maintenance Agreements	The Company enters into non-cancelable contractual obligations for software licenses and maintenance agreements. As of March 31, 2021, the minimum aggregate payments due under specified non-cancelable contractual obligations are summarized as follows: Non-cancelable contractual obligations Remaining 9 months of 2021 $ 313 2022 — 2023 — 2024 — 2025 — Thereafter — $ 313
Schedule of Changes in Aggregate Product Warranty Liabilities	The following table identifies the changes in the Company’s aggregate product warranty liabilities for the three and twelve-month periods ended March 31, 2021 and December 31, 2020, respectively: March 31, December 31, 2021 2020 Product warranty liability at beginning of period $ 14,394 $ 12,571 Accruals for warranties issued 2,966 9,462 Adjustments related to preexisting warranties (including changes in estimates) (330 ) (754 ) Settlements made (in cash or in kind) (2,116 ) (6,885 ) Product warranty liability at end of period $ 14,914 $ 14,394

Business Overview - Additional

Business Overview - Additional Information (Details)	3 Months Ended
	Mar. 31, 2021Product
Inogen Europe Holding B.V.
Business Overview Disclosures [Line Items]
Date of incorporation of subsidiary	Apr. 13, 2017
Minimum | Inogen One
Business Overview Disclosures [Line Items]
Number of portable oxygen concentrators	1,023,000

Basis of Presentation and Sum_3

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended
	Mar. 31, 2021Segment
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of operating segments	1
Number of reportable segments	1
ASU 2019-12
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Jan. 1, 2021
Change in accounting principle, accounting standards update, immaterial effect	true

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Fair Value Assets Measured on Recurring Basis for Cash, Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 220,014	$ 211,962
Fair Value Measurements Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Adjusted cost	233,147	231,219
Gross unrealized gains (losses)	3
Fair value	233,150	231,219
Cash and cash equivalents	220,014	211,962
Marketable securities	13,136	19,257
Fair Value Measurements Recurring | Cash
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Adjusted cost	48,706	52,812
Fair value	48,706	52,812
Cash and cash equivalents	48,706	52,812
Fair Value Measurements Recurring | Level 1 | Money Market Accounts
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Adjusted cost	171,308	159,150
Fair value	171,308	159,150
Cash and cash equivalents	171,308	159,150
Fair Value Measurements Recurring | Level 2 | Corporate Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Adjusted cost	5,477	11,549
Gross unrealized gains (losses)	(1)	(1)
Fair value	5,476	11,548
Marketable securities	5,476	11,548
Fair Value Measurements Recurring | Level 2 | U.S. Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Adjusted cost	4,053	4,107
Gross unrealized gains (losses)	1
Fair value	4,054	4,107
Marketable securities	4,054	4,107
Fair Value Measurements Recurring | Level 2 | Agency Mortgage-backed Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Adjusted cost	3,603	3,601
Gross unrealized gains (losses)	3	1
Fair value	3,606	3,602
Marketable securities	$ 3,606	$ 3,602

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Related receivables	$ 38,425,000	$ 29,717,000
Preacquisition loss recoveries	672,000	672,000
Fair Value Measurements Recurring | Level 3 | Maximum
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Earnout liability	31,400,000
Forward Contracts
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Related receivables	$ 246,000
Payable		$ 863,000

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	$ 349,623	$ 344,621
Other comprehensive income (loss)	450	509
Ending Balance	356,284	347,300
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	1,128
Other comprehensive income (loss)	(457)
Ending Balance	671
Unrealized Gains (Losses) on Marketable Securities
Accumulated Other Comprehensive Income Loss [Line Items]
Other comprehensive income (loss)	4
Ending Balance	4
Unrealized Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(653)
Other comprehensive income (loss)	903
Ending Balance	250
Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	475	(87)
Other comprehensive income (loss)	450	509
Ending Balance	$ 925	$ 422

Fair Value Measurements - Sum_3

Fair Value Measurements - Summary of Quantitative Information about Level 3 Inputs for Fair Value Measurement of Earnout Liability (Details) - Level 3	Mar. 31, 2021	Dec. 31, 2020
Revenue Volatility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Earnout liability, measurement input	35	35
WACC
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Earnout liability, measurement input	12.50	12
20-Year Risk Free Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Earnout liability, measurement input	2.31	1.45
Market Price of Risk
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Earnout liability, measurement input	9	8

Fair Value Measurements - Sum_4

Fair Value Measurements - Summary of Reconciliation of Earnout Liability Measured and Carried Fair Value on a Recurring Basis (Details) - Fair Value Measurements Recurring $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning Balance	$ 27,612
Change in fair value	265
Ending Balance	$ 27,877

Balance Sheet Components - Summ

Balance Sheet Components - Summary of Cash, Cash Equivalents and Short-term Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Cash and cash equivalents
Cash	$ 48,706	$ 52,812
Money market accounts	171,308	159,150
Total cash and cash equivalents	220,014	211,962
Marketable securities
Marketable securities	13,136	19,257
Corporate Bonds
Marketable securities
Marketable securities	5,476	11,548
Agency Mortgage-backed Securities
Marketable securities
Marketable securities	3,606	3,602
U.S. Treasury Securities
Marketable securities
Marketable securities	$ 4,054	$ 4,107

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details)	3 Months Ended
	Mar. 31, 2021USD ($)Customer	Mar. 31, 2020USD ($)Customer	Dec. 31, 2020USD ($)
Schedule Of Balance Sheet Components [Line Items]
Unbilled Receivables	$ 569,000		$ 459,000
Accounts receivable, net	$ 38,425,000		29,717,000
Percentage of Non-US revenue invoiced in Euros	79.30%	68.70%
Transfer of inventory to rental equipment	$ 607,000	$ 368,000
Salvage value of expenditures for additions, improvements and replacements	0
Repairs and maintenance expense	935,000	524,000
Depreciation and amortization	2,834,000	2,220,000
Impairments of long-lived assets	0	0
Impairment of finite lived intangible assets	0	0
Goodwill impairment loss	0
Construction in Process and Computer Software or Development Cost
Schedule Of Balance Sheet Components [Line Items]
Depreciation and amortization	0	$ 0
Other Noncurrent Assets
Schedule Of Balance Sheet Components [Line Items]
Noncurrent inventories expected to be realized or consumed	1,145,000		1,153,000
Customer Concentration Risk | Customer One
Schedule Of Balance Sheet Components [Line Items]
Accounts receivable, net	10,434,000		8,417,000
Customer Concentration Risk | Customer Two
Schedule Of Balance Sheet Components [Line Items]
Accounts receivable, net	$ 8,102,000		$ 7,044,000
Sales Revenue, Net | Customer Concentration Risk
Schedule Of Balance Sheet Components [Line Items]
Number of customers | Customer	1
Net Accounts Receivable | Customer Concentration Risk
Schedule Of Balance Sheet Components [Line Items]
Number of customers | Customer		2
Raw materials | Supplier Concentration Risk | Vendor one
Schedule Of Balance Sheet Components [Line Items]
Concentration risk, percentage	19.90%	23.60%
Raw materials | Supplier Concentration Risk | Vendor two
Schedule Of Balance Sheet Components [Line Items]
Concentration risk, percentage	10.80%	15.20%
Raw materials | Supplier Concentration Risk | Vendor three
Schedule Of Balance Sheet Components [Line Items]
Concentration risk, percentage	9.60%	9.40%

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Gross Accounts Receivable Balance Concentrations by Major Category (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Accounts Notes And Loans Receivable [Line Items]
Gross accounts receivable	$ 39,756	$ 30,907
Rental
Accounts Notes And Loans Receivable [Line Items]
Gross accounts receivable	5,701	4,190
Business To Business And Other Receivables
Accounts Notes And Loans Receivable [Line Items]
Gross accounts receivable	$ 34,055	$ 26,717

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Net Accounts Receivable Balance Concentrations by Major Category (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Accounts Notes And Loans Receivable [Line Items]
Net accounts receivable	$ 38,425	$ 29,717
Rental
Accounts Notes And Loans Receivable [Line Items]
Net accounts receivable	5,316	3,794
Business To Business And Other Receivables
Accounts Notes And Loans Receivable [Line Items]
Net accounts receivable	$ 33,109	$ 25,923

Balance Sheet Components - Sc_3

Balance Sheet Components - Schedule of Net Accounts Receivable Balance Concentrations by Major Category (Parenthetical) (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2021USD ($)Customer	Dec. 31, 2020USD ($)Customer
Accounts Notes And Loans Receivable [Line Items]
Gross accounts receivable	$ 39,756,000	$ 30,907,000
Customer Concentration Risk | Business To Business Receivables
Accounts Notes And Loans Receivable [Line Items]
Number of customers | Customer	1	1
Gross accounts receivable	$ 8,102,000	$ 7,044,000
Credit insurance policy, deductible amount	$ 400,000
Credit insurance policy, retention percentage	10.00%
Customer Concentration Risk | Business To Business Receivables | Maximum
Accounts Notes And Loans Receivable [Line Items]
Credit insurance policy, coverage limit	$ 10,000,000	$ 10,000,000

Balance Sheet Components - Sc_4

Balance Sheet Components - Schedule of Allowances for Accounts Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Allowances - accounts receivable
Doubtful accounts	$ 21	$ 52
Rental revenue adjustments	385	396
Sales returns	925	742
Total allowances - accounts receivable	$ 1,331	$ 1,190

Balance Sheet Components - Brea

Balance Sheet Components - Breakdown of the Company Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Concentration Risk [Line Items]
Revenues	$ 86,932	$ 88,489
U.S. revenue
Concentration Risk [Line Items]
Revenues	71,212	68,406
Non-U.S. revenue
Concentration Risk [Line Items]
Revenues	$ 15,720	$ 20,083

Balance Sheet Components - Sc_5

Balance Sheet Components - Schedule of Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Inventory Disclosure [Abstract]
Raw materials and work-in-progress	$ 24,210	$ 22,318
Finished goods	3,541	3,743
Less: reserves	(1,357)	(1,246)
Inventories, net	$ 26,394	$ 24,815

Balance Sheet Components - Comp

Balance Sheet Components - Computation of Depreciation and Amortization Using Straight Line Method Over Estimated Useful Lives of Assets (Details)	3 Months Ended
	Mar. 31, 2021
Rental equipment | Minimum
Property Plant And Equipment [Line Items]
Property Plant And Equipment Useful Life	1 year 6 months
Rental equipment | Maximum
Property Plant And Equipment [Line Items]
Property Plant And Equipment Useful Life	5 years
Manufacturing equipment and tooling | Minimum
Property Plant And Equipment [Line Items]
Property Plant And Equipment Useful Life	3 years
Manufacturing equipment and tooling | Maximum
Property Plant And Equipment [Line Items]
Property Plant And Equipment Useful Life	5 years
Computer equipment and software | Minimum
Property Plant And Equipment [Line Items]
Property Plant And Equipment Useful Life	2 years
Computer equipment and software | Maximum
Property Plant And Equipment [Line Items]
Property Plant And Equipment Useful Life	3 years
Furniture and equipment | Minimum
Property Plant And Equipment [Line Items]
Property Plant And Equipment Useful Life	3 years
Furniture and equipment | Maximum
Property Plant And Equipment [Line Items]
Property Plant And Equipment Useful Life	5 years
Leasehold improvements
Property Plant And Equipment [Line Items]
Property Plant And Equipment Useful Life	Lesser of estimated useful life or remaining lease term

Balance Sheet Components - Su_2

Balance Sheet Components - Summary of Depreciation and Amortization Expense of Rental Equipment and Other Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Property Plant And Equipment [Line Items]
Depreciation	$ 1,888	$ 1,299
Depreciation and amortization	2,834	2,220
Rental equipment
Property Plant And Equipment [Line Items]
Depreciation	1,888	1,299
Other property and equipment
Property Plant And Equipment [Line Items]
Depreciation and amortization	$ 946	$ 921

Balance Sheet Components - Su_3

Balance Sheet Components - Summary of Property Plant and Equipment and Rental Equipment with Associated Accumulated Depreciation (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Property and equipment	$ 78,514	$ 74,024
Accumulated depreciation	47,461	45,794
Property and equipment, net	31,053	28,230
Rental equipment
Property Plant And Equipment [Line Items]
Property and equipment	49,872	46,953
Accumulated depreciation	31,016	30,283
Property and equipment, net	18,856	16,670
Other property and equipment
Property Plant And Equipment [Line Items]
Property and equipment	28,642	27,071
Accumulated depreciation	16,445	15,511
Property and equipment, net	$ 12,197	$ 11,560

Balance Sheet Components - Su_4

Balance Sheet Components - Summary of Property Plant and Equipment and Rental Equipment with Associated Accumulated Depreciation (Parenthetical) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Rental equipment, allowance	$ 650	$ 575

Balance Sheet Components - Sc_6

Balance Sheet Components - Schedule of Changes in Carrying Amount of Goodwill (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
Balance as of December 31, 2020	$ 33,165
Translation adjustment	(110)
Balance as of March 31, 2021	$ 33,055

Balance Sheet Components - Su_5

Balance Sheet Components - Summary of Changes in Net Carrying Values of Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Finite Lived Intangible Assets [Line Items]
Gross carrying amount	$ 84,539	$ 84,580
Accumulated amortization	17,982	15,783
Net amount	$ 66,557	$ 68,797
Technology
Finite Lived Intangible Assets [Line Items]
Average estimated useful lives (in years)	10 years	10 years
Gross carrying amount	$ 77,700	$ 77,700
Accumulated amortization	12,626	10,684
Net amount	$ 65,074	$ 67,016
Licenses
Finite Lived Intangible Assets [Line Items]
Average estimated useful lives (in years)	10 years	10 years
Gross carrying amount	$ 185	$ 185
Accumulated amortization	176	174
Net amount	$ 9	$ 11
Patents And Websites
Finite Lived Intangible Assets [Line Items]
Average estimated useful lives (in years)	5 years	5 years
Gross carrying amount	$ 4,488	$ 4,488
Accumulated amortization	3,197	3,015
Net amount	$ 1,291	$ 1,473
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Average estimated useful lives (in years)	4 years	4 years
Gross carrying amount	$ 1,407	$ 1,474
Accumulated amortization	1,378	1,351
Net amount	29	123
Commercials
Finite Lived Intangible Assets [Line Items]
Gross carrying amount	759	733
Accumulated amortization	605	559
Net amount	$ 154	$ 174
Commercials | Minimum
Finite Lived Intangible Assets [Line Items]
Average estimated useful lives (in years)	2 years	2 years
Commercials | Maximum
Finite Lived Intangible Assets [Line Items]
Average estimated useful lives (in years)	3 years	3 years

Balance Sheet Components - Sc_7

Balance Sheet Components - Schedule of Annual Estimated Amortization Expense (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Remaining 9 months of 2021	$ 6,488
2022	8,431
2023	7,856
2024	7,832
2025	7,784
Thereafter	28,166
Net amount	$ 66,557	$ 68,797

Balance Sheet Components - Sc_8

Balance Sheet Components - Schedule of Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Accounts payable	$ 14,606	$ 12,520
Accrued inventory (in-transit and unvouchered receipts) and trade payables	9,666	9,023
Accrued litigation settlement		8,000
Accrued purchasing card liability	4,051	2,468
Accrued franchise, sales and use taxes	482	449
Other accrued expenses	544	1,252
Accounts payable and accrued expenses	$ 29,349	$ 33,712

Balance Sheet Components - Sc_9

Balance Sheet Components - Schedule of Accrued Payroll (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued bonuses	$ 1,166	$ 4
Accrued wages and other payroll related items	4,873	3,796
Accrued vacation	2,970	2,642
Accrued employee stock purchase plan deductions	182	649
Accrued payroll	$ 9,191	$ 7,091

Leases - Additional Information

Leases - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Lessee Lease Description [Line Items]
Operating lease, option to extend	options to extend the leases for up to 5 years.
Operating lease, existence of option to extend [true false]	true
Rent expense, including short-term lease cost	$ 987,000	$ 751,000
Corporate Headquarters in California
Lessee Lease Description [Line Items]
Operating leases, lease term	10 years
Annual percentage increase in rental expense	3.50%
Lease payments annual increase description	Lease payments for its corporate headquarters will increase annually by the lesser of the change, if any, in the Consumer Price Index of the Bureau of Labor Statistics of the U.S. Department of Labor or three and one-half percent (3.5%) at each annual adjustment date thereafter.
Minimum
Lessee Lease Description [Line Items]
Operating leases, lease term	2 years
Minimum | Corporate Headquarters in California
Lessee Lease Description [Line Items]
Additional operating lease cost	$ 11,359,000
Maximum
Lessee Lease Description [Line Items]
Operating leases, lease term	11 years
Operating lease option to extend term	5 years

Leases - Schedule of Right-of-U

Leases - Schedule of Right-of-Use Assets and Operating Lease Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Cash paid for operating lease liabilities	$ 554	$ 593
Operating lease cost	763	632
Non-cash right-of-use assets obtained in exchange for new operating lease obligations	$ 9,340	$ 2,809
Weighted-average remaining lease term	3 years	2 years 6 months
Weighted-average discount rate	3.20%	3.70%

Leases - Schedule of Maturities

Leases - Schedule of Maturities of Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Maturities of lease liabilities due in the 12-month period ending March 31,
2022	$ 2,878
2023	2,781
2024	2,799
2025	2,213
2026	1,564
Thereafter	8,452
Operating lease liabilities payments due	20,687
Less imputed interest	(1,777)
Total lease liabilities	18,910
Operating lease liability - current	2,475	$ 1,931
Operating lease liability - noncurrent	16,435	$ 8,078
Total lease liabilities	$ 18,910

Earnings (loss) per Share - Com

Earnings (loss) per Share - Computation of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator—basic and diluted:
Net loss	$ (732)	$ (1,589)
Denominator:
Weighted-average common shares - basic common stock	22,181,394	21,916,365
Weighted-average common shares - diluted common stock	22,181,394	21,916,365
Net loss per share - basic common stock	$ (0.03)	$ (0.07)
Net loss per share - diluted common stock	$ (0.03)	$ (0.07)
Denominator calculation from basic to diluted:
Weighted-average common shares - basic common stock	22,181,394	21,916,365
Stock options and other dilutive awards	341,716	327,891
Weighted-average common shares - diluted common stock	22,523,110	22,244,256
Shares excluded from diluted weighted-average shares:
Shares excluded from diluted weighted-average shares	373,285	374,456
Stock options
Shares excluded from diluted weighted-average shares:
Shares excluded from diluted weighted-average shares	64,498	81,220
Restricted stock units and restricted stock awards
Shares excluded from diluted weighted-average shares:
Shares excluded from diluted weighted-average shares	308,787	293,236

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Class Of Stock [Line Items]
Total intrinsic value of options exercised	$ 6,504	$ 239
401(k) Retirement Savings Plan
Class Of Stock [Line Items]
Defined benefit plan, contributed by employer net of forfeitures	$ 0	$ 252
Time based restricted stock units
Class Of Stock [Line Items]
Vesting period	4 years
Time based restricted stock awards
Class Of Stock [Line Items]
Vesting period	4 years
Performance and time based restricted stock awards
Class Of Stock [Line Items]
Vesting period	3 years
Performance and time based restricted stock units
Class Of Stock [Line Items]
Vesting period	3 years
Restricted stock units and restricted stock awards
Class Of Stock [Line Items]
Unrecognized compensation cost related to unvested employee excluding estimated forfeitures	$ 21,694
Amount expected to recognized over weighted-average period	2 years 9 months 18 days
Maximum | Stock options
Class Of Stock [Line Items]
Stock option period, expiration	10 years
Vesting period	4 years
Minimum | Stock options
Class Of Stock [Line Items]
Stock option period, expiration	7 years
Vesting period	1 year
2002 Plan
Class Of Stock [Line Items]
Stock option shares outstanding	0
Number of equity awards available for grant	0
2012 Plan
Class Of Stock [Line Items]
Stock option shares outstanding	119,840
Number of equity awards available for grant	0
2014 Plan
Class Of Stock [Line Items]
Stock option shares outstanding	1,146,603
Number of equity awards available for grant	1,380,980
Terms of shares available for issuance	The number of shares available for issuance under the 2014 Plan also is increased annually on the first day of each fiscal year equal to the least of: 895,346 shares; 4% of the outstanding shares of common stock as of the last day of the Company's immediately preceding fiscal year; or such other amount as the Company's board of directors may determine.
Common stock capital shares reserved for future issuance maximum annual increase	895,346
Percentage on outstanding shares of common stock	4.00%
Number of additional number of shares reserve to provision	0
2012 Plan and 2002 Plan | Maximum
Class Of Stock [Line Items]
Stock option shares outstanding	2,328,569
2014 ESPP Plan
Class Of Stock [Line Items]
Number of equity awards available for grant	592,466
Terms of shares available for issuance	The number of shares available for sale under the ESPP is increased annually on the first day of each fiscal year equal to the least of: 179,069 shares; 1.5% of the outstanding shares of the Company's common stock on the last day of the Company's immediately preceding fiscal year; or such other amount as may be determined by the administrator.
Percentage on outstanding shares of common stock	1.50%
Number of additional number of shares reserve to provision	0
Maximum percentage of common stock eligible to purchase through payroll deductions for participants	15.00%
Maximum number of shares available for participant to purchase during period	1,500
Purchase price as percentage of stock price on offering period	85.00%
Purchase price as percentage of stock price on exercise date	85.00%
Potential increase of shares available for issuance	179,069

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Stock Options Activity (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Class Of Stock [Line Items]
Stock Options Outstanding, Beginning balance	955,479
Stock Options, Exercised	(205,753)
Stock Options Outstanding, Ending balance	749,726	955,479
Stock Options, Vested and exercisable	749,726
Stock Options, Vested and expected to vest	749,726
Outstanding, Weighted-average exercise price, Beginning balance	$ 35.49
Weighted-average exercise price, Exercised	18.79
Outstanding, Weighted-average exercise price, Ending balance	40.07	$ 35.49
Weighted-average exercise price, Vested and exercisable	40.07
Weighted-average exercise price, Vested and expected to vest	$ 40.07
Remaining weighted-average contractual term, Outstanding	1 year 11 months 15 days	1 year 10 months 6 days
Remaining weighted-average contractual term, Vested and exercisable	1 year 11 months 15 days
Remaining weighted-average contractual term, Vested and expected to vest	1 year 11 months 15 days
Outstanding, Per share average intrinsic value	$ 15.09	$ 11.81
Per share average intrinsic value, Vested and exercisable	15.09
Per share average intrinsic value, Vested and expected to vest	15.09
Minimum
Class Of Stock [Line Items]
Outstanding, Price per share, Beginning balance	0.75
Price per share, Exercised	0.75
Outstanding, Price per share, Ending balance	0.81	0.75
Price per share, Vested and exercisable	0.81
Price per share, Vested and expected to vest	0.81
Maximum
Class Of Stock [Line Items]
Outstanding, Price per share, Beginning balance	83.30
Price per share, Exercised	46.66
Outstanding, Price per share, Ending balance	83.30	$ 83.30
Price per share, Vested and exercisable	83.30
Price per share, Vested and expected to vest	$ 83.30

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of Restricted Stock Activity (Details)	3 Months Ended
	Mar. 31, 2021$ / sharesshares
Time based restricted stock units
Class Of Stock [Line Items]
Unvested restricted stock units/ awards outstanding, Beginning balance	245,462
Granted	171,340
Vested	(39,293)
Forfeited/canceled	(3,742)
Unvested restricted stock units/ awards outstanding, Ending balance	373,767
Performance and time based restricted stock units
Class Of Stock [Line Items]
Unvested restricted stock units/ awards outstanding, Beginning balance	88,458
Granted	88,902
Forfeited/canceled	(29,485)
Unvested restricted stock units/ awards outstanding, Ending balance	147,875
Restricted stock units
Class Of Stock [Line Items]
Unvested restricted stock units/ awards outstanding, Beginning balance	333,920
Granted	260,242
Vested	(39,293)
Forfeited/canceled	(33,227)
Unvested restricted stock units/ awards outstanding, Ending balance	521,642
Unvested and expected to vest restricted stock units/awards outstanding	411,867
Weighted-average grant date fair value per share, Unvested restricted stock units/ awards outstanding, Beginning balance | $ / shares	$ 49.29
Weighted-average grant date fair value per share, Granted | $ / shares	53.14
Weighted-average grant date fair value per share, Vested | $ / shares	52.58
Weighted-average grant date fair value per share, Forfeited/canceled | $ / shares	48.08
Weighted-average grant date fair value per share, Unvested restricted stock units/ awards outstanding, Ending balance | $ / shares	50.95
Weighted-average grant date fair value per share, Unvested and expected to vest restricted stock units/awards outstanding | $ / shares	$ 51.09
Time based restricted stock awards
Class Of Stock [Line Items]
Unvested restricted stock units/ awards outstanding, Beginning balance	42,076
Vested	(5,609)
Unvested restricted stock units/ awards outstanding, Ending balance	36,467
Performance and time based restricted stock awards
Class Of Stock [Line Items]
Unvested restricted stock units/ awards outstanding, Beginning balance	33,355
Forfeited/canceled	(21,510)
Unvested restricted stock units/ awards outstanding, Ending balance	11,845
Restricted stock awards
Class Of Stock [Line Items]
Unvested restricted stock units/ awards outstanding, Beginning balance	75,431
Vested	(5,609)
Forfeited/canceled	(21,510)
Unvested restricted stock units/ awards outstanding, Ending balance	48,312
Unvested and expected to vest restricted stock units/awards outstanding	38,978
Weighted-average grant date fair value per share, Unvested restricted stock units/ awards outstanding, Beginning balance | $ / shares	$ 93.96
Weighted-average grant date fair value per share, Vested | $ / shares	90.24
Weighted-average grant date fair value per share, Forfeited/canceled | $ / shares	118.41
Weighted-average grant date fair value per share, Unvested restricted stock units/ awards outstanding, Ending balance | $ / shares	86.52
Weighted-average grant date fair value per share, Unvested and expected to vest restricted stock units/awards outstanding | $ / shares	$ 85.32

Stockholders' Equity - Summar_3

Stockholders' Equity - Summary of Stock-based Compensation Expense Recognized (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Stock-based compensation expense by type of award:
Stock-based compensation expense	$ 2,516	$ 2,784
Stock Option Plan Awards
Stock-based compensation expense by type of award:
Stock-based compensation expense		525
Restricted stock units and restricted stock awards
Stock-based compensation expense by type of award:
Stock-based compensation expense	2,330	2,083
Employee Stock Purchase Plan
Stock-based compensation expense by type of award:
Stock-based compensation expense	$ 186	$ 176

Stockholders' Equity - Summar_4

Stockholders' Equity - Summary of Stock-based Compensation Expense Recognized in Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Class Of Stock [Line Items]
Stock-based compensation expense	$ 2,516	$ 2,784
Cost of Revenue
Class Of Stock [Line Items]
Stock-based compensation expense	238	229
Research and Development
Class Of Stock [Line Items]
Stock-based compensation expense	298	320
Sales and Marketing
Class Of Stock [Line Items]
Stock-based compensation expense	612	612
General and Administrative
Class Of Stock [Line Items]
Stock-based compensation expense	$ 1,368	$ 1,623

Commitments and Contingencies -

Commitments and Contingencies - Minimum Aggregate Payments Due under Operating Leases and Specified Non-Cancelable Contractual Obligations Consist of Software License and Maintenance Agreements (Details) $ in Thousands	Mar. 31, 2021USD ($)
Commitments And Contingencies Disclosure [Abstract]
Non-cancelable contractual obligations, Remaining 9 months of 2020	$ 313
Non-cancelable contractual obligations, Total minimum payments	$ 313

Commitments and Contingencies_2

Commitments and Contingencies - Additional Information (Details) $ in Thousands	1 Months Ended	3 Months Ended
	Oct. 31, 2019Lawsuit	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Jan. 13, 2020Lawsuit	May 20, 2019Lawsuit	May 15, 2019Lawsuit
Commitments And Contingencies [Line Items]
Outstanding purchase orders due within one year with its outside vendors and suppliers		$ 64,400
Payments received in advance of satisfying performance obligations		1,604
Performance obligation partially offset of revenue recognized		1,375
Number of lawsuits | Lawsuit					2
No. of additional shareholder derivative who filed lawsuits | Lawsuit	3
Number of derivative lawsuits | Lawsuit				4		2
Lifetime Warranties | Direct-to-Consumer
Commitments And Contingencies [Line Items]
Deferred revenue related to life time warranties		$ 17,307	$ 17,078

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Changes in Aggregate Product Warranty Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Product warranty liability at beginning of period	$ 14,394	$ 12,571
Accruals for warranties issued	2,966	9,462
Adjustments related to preexisting warranties (including changes in estimates)	(330)	(754)
Settlements made (in cash or in kind)	(2,116)	(6,885)
Product warranty liability at end of period	$ 14,914	$ 14,394

Foreign Currency Exchange Con_2

Foreign Currency Exchange Contracts and Hedging - Additional Information (Details)	3 Months Ended
	Mar. 31, 2021USD ($)Contract	Mar. 31, 2020USD ($)Contract
Derivatives Fair Value [Line Items]
Number of contract designated hedges | Contract	22	8
Number of contract non-designated hedges | Contract	2	1
Non-Designated Derivative Contracts
Derivatives Fair Value [Line Items]
Derivative contracts notional amounts	$ 1,704,000	$ 3,885,000
Designated Derivative Contracts
Derivatives Fair Value [Line Items]
Derivative contracts notional amounts	20,491,000	23,788,000
Unrealized gain (loss) on derivative	$ 903,000	$ 673,000
Minimum
Derivatives Fair Value [Line Items]
Derivative contracts expiration period	1 month
Maximum
Derivatives Fair Value [Line Items]
Derivative contracts expiration period	12 months