Etsy (ETSY) 10-Q 6 May 21 2021 Q1 Quarterly report Financial data

Cover

Cover - shares	3 Months Ended
	Mar. 31, 2021	Apr. 30, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	001-36911
Entity Registrant Name	ETSY, INC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-4898921
Entity Address, Address Line One	117 Adams Street
Entity Address, City or Town	Brooklyn
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	11201
City Area Code	718
Local Phone Number	880-3660
Title of 12(b) Security	Common Stock
Trading Symbol	ETSY
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		127,102,598
Entity Central Index Key	0001370637
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 1,163,678	$ 1,244,099
Short-term investments	502,569	425,119
Accounts receivable, net of expected credit losses of $10,811 and $9,757 as of March 31, 2021 and December 31, 2020, respectively	22,991	22,605
Prepaid and other current assets	46,277	56,152
Funds receivable and seller accounts	158,104	146,806
Total current assets	1,893,619	1,894,781
Restricted cash	5,341	5,341
Property and equipment, net of accumulated depreciation and amortization of $156,287 and $158,771 as of March 31, 2021 and December 31, 2020, respectively	107,960	112,495
Goodwill	139,745	140,810
Intangible assets, net of accumulated amortization of $29,132 and $25,705 as of March 31, 2021 and December 31, 2020, respectively	182,312	187,449
Deferred tax assets	7,723	115
Long-term investments	137,655	39,094
Other assets	23,056	24,404
Total assets	2,497,411	2,404,489
Current liabilities:
Accounts payable	16,386	40,883
Accrued expenses	218,157	232,352
Finance lease obligations—current	8,639	8,537
Funds payable and amounts due to sellers	158,104	146,806
Deferred revenue	12,260	11,264
Other current liabilities	13,499	14,822
Total current liabilities	427,045	454,664
Finance lease obligations—net of current portion	43,042	44,979
Deferred tax liabilities	33	58,481
Long-term debt, net	1,302,345	1,062,299
Other liabilities	41,172	41,642
Total liabilities	1,813,637	1,662,065
Commitments and contingencies
Stockholders’ equity:
Common stock ($0.001 par value, 1,400,000,000 shares authorized as of March 31, 2021 and December 31, 2020; 126,785,568 and 125,835,931 shares issued and outstanding as of March 31, 2021 and December 31, 2020, respectively)	127	126
Preferred stock ($0.001 par value, 25,000,000 shares authorized as of March 31, 2021 and December 31, 2020)	0	0
Additional paid-in capital	664,240	883,166
Retained earnings (accumulated deficit)	24,775	(146,819)
Accumulated other comprehensive (loss) income	(5,368)	5,951
Total stockholders’ equity	683,774	742,424
Total liabilities and stockholders’ equity	$ 2,497,411	$ 2,404,489

Consolidated Balance Sheets (_2

Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Accounts receivable, expected credit losses	$ 10,811	$ 9,757
Property and equipment, accumulated depreciation and amortization	156,287	158,771
Accumulated amortization	$ 29,132	$ 25,705
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	1,400,000,000	1,400,000,000
Common stock, shares issued (in shares)	126,785,568	126,785,568
Common stock, shares outstanding (in shares)	125,835,931	125,835,931
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	25,000,000	25,000,000

Consolidated Statements of Oper

Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Revenue	$ 550,646	$ 228,055
Cost of revenue	142,917	82,416
Gross profit	407,729	145,639
Operating expenses:
Marketing	151,204	48,505
Product development	53,706	37,782
General and administrative	52,182	33,987
Total operating expenses	257,092	120,274
Income from operations	150,637	25,365
Other income (expense):
Interest expense	(1,685)	(9,967)
Interest and other income	979	3,613
Foreign exchange gain (loss)	7,797	(9,318)
Total other income (expense)	7,091	(15,672)
Income before income taxes	157,728	9,693
(Provision) benefit for income taxes	(13,962)	2,829
Net income	$ 143,766	$ 12,522
Net income per share attributable to common stockholders:
Basic (in dollars per share)	$ 1.14	$ 0.11
Diluted (in dollars per share)	$ 1	$ 0.10
Weighted-average common shares outstanding:
Basic (in shares)	126,214,735	118,138,186
Diluted (in shares)	144,714,686	123,119,053

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 143,766	$ 12,522
Other comprehensive loss:
Cumulative translation adjustment	(11,064)	(2,671)
Unrealized (losses) gains on marketable securities, net of tax (benefit) expense of $(80) and $205, respectively	(255)	671
Total other comprehensive loss	(11,319)	(2,000)
Comprehensive income	$ 132,447	$ 10,522

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Unrealized (losses) gains on marketable securities, tax expense (benefit)	$ (80)	$ 205

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders’ Equity (Unaudited) - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-in Capital	Additional Paid-in CapitalCumulative Effect, Period of Adoption, Adjustment	(Accumulated Deficit) Retained Earnings	(Accumulated Deficit) Retained EarningsCumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2019			118,342,772
Beginning balance at Dec. 31, 2019	$ 406,634		$ 119	$ 642,628		$ (227,414)		$ (8,699)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	13,985			13,985
Exercise of vested options (in shares)			447,886
Exercise of vested options	4,896			4,896
Vesting of restricted stock units, net of shares withheld (in shares)			129,230
Vesting of restricted stock units, net of shares withheld	(4,198)			(4,198)
Stock repurchase (in shares)			(543,106)
Stock repurchase	(24,992)		$ (1)			(24,991)
Other comprehensive loss	(2,000)							(2,000)
Net income	12,522					12,522
Ending balance (in shares) at Mar. 31, 2020			118,376,782
Ending balance at Mar. 31, 2020	$ 406,847		$ 118	657,311		(239,883)		(10,699)
Accounting Standards Update [Extensible List]	Accounting Standards Update 2020-06
Beginning balance (in shares) at Dec. 31, 2019			118,342,772
Beginning balance at Dec. 31, 2019	$ 406,634		$ 119	642,628		(227,414)		(8,699)
Ending balance (in shares) at Dec. 31, 2020	125,835,931		125,835,931
Ending balance at Dec. 31, 2020	$ 742,424	$ (200,910)	$ 126	883,166	$ (228,738)	(146,819)	$ 27,828	5,951
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	$ 20,976			20,976
Exercise of vested options (in shares)	217,293		217,293
Exercise of vested options	$ 3,930			3,930
Settlement of convertible senior notes, net of taxes (in shares)			625,022
Settlement of convertible senior notes, net of taxes	(291)		$ 1	(292)
Vesting of restricted stock units, net of shares withheld (in shares)			107,322
Vesting of restricted stock units, net of shares withheld	(14,802)			(14,802)
Other comprehensive loss	(11,319)							(11,319)
Net income	$ 143,766					143,766
Ending balance (in shares) at Mar. 31, 2021	125,835,931		126,785,568
Ending balance at Mar. 31, 2021	$ 683,774		$ 127	$ 664,240		$ 24,775		$ (5,368)

Condensed Consolidated Statemen

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities
Net income	$ 143,766	$ 12,522
Adjustments to reconcile net income to net cash provided by operating activities:
Stock-based compensation expense	20,351	13,811
Depreciation and amortization expense	13,080	15,163
Provision for expected credit losses	4,601	3,684
Foreign exchange (gain) loss	(4,395)	8,157
Non-cash interest expense	271	8,570
Deferred benefit for income taxes	(3,068)	(2,829)
Other non-cash expense, net	1,184	530
Changes in operating assets and liabilities:
Current assets	(11,580)	(2,784)
Non-current assets	1,231	915
Current liabilities	(16,597)	(27,235)
Non-current liabilities	(379)	(840)
Net cash provided by operating activities	148,465	29,664
Cash flows from investing activities
Purchases of property and equipment	(526)	(567)
Development of internal-use software	(3,226)	(1,261)
Purchases of marketable securities	(268,972)	(101,501)
Sales and maturities of marketable securities	91,714	109,422
Net cash (used in) provided by investing activities	(181,010)	6,093
Cash flows from financing activities
Payment of tax obligations on vested equity awards	(14,802)	(4,198)
Repurchase of stock	0	(24,992)
Proceeds from exercise of stock options	3,930	4,896
Payment of debt issuance costs	(25)	(14)
Settlement of convertible senior notes	(27,319)	0
Payments on finance lease obligations	(2,421)	(2,566)
Other financing, net	1,259	(5,804)
Net cash used in financing activities	(39,378)	(32,678)
Effect of exchange rate changes on cash	(8,498)	(4,018)
Net decrease in cash, cash equivalents, and restricted cash	(80,421)	(939)
Cash, cash equivalents, and restricted cash at beginning of period	1,249,440	448,634
Cash, cash equivalents, and restricted cash at end of period	1,169,019	447,695
Reconciliation of cash, cash equivalents, and restricted cash
Total cash and cash equivalents, and restricted cash	$ 1,169,019	$ 448,634

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows (Unaudited) (Parenthetical) - Convertible Senior Notes Due 2023 - Convertible Debt - shares shares in Millions	3 Months Ended
	Mar. 31, 2021	Sep. 30, 2020	Mar. 31, 2018
Debt instrument conversion amount, shares (in shares)	0.6	7.3
Debt instrument, interest rate, stated percentage			0.00%

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	Note 1—Basis of Presentation and Summary of Significant Accounting Policies Description of Business Etsy, Inc. (the “Company” or “Etsy”) operates two-sided online marketplaces that connect millions of passionate and creative buyers and sellers. Our primary marketplace, Etsy.com, is the global marketplace for unique and creative goods. The Company generates revenue primarily from transaction, listing, and payments processing fees, and on-site advertising and shipping label services. Basis of Consolidation The consolidated financial statements include the accounts of Etsy and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Basis of Presentation The accompanying unaudited interim consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and pursuant to the applicable rules and regulations of the Securities and Exchange Commission (“SEC”). The Company has condensed or omitted certain information and notes normally included in complete annual financial statements prepared in accordance with GAAP. These unaudited interim consolidated financial statements should therefore be read in conjunction with the audited consolidated financial statements and accompanying notes included in the Company’s Annual Report on Form 10-K filed with the SEC on February 26, 2021 (the “Annual Report”). In the opinion of management, all material adjustments, which are of a normal and recurring nature, necessary for a fair presentation of the results for the periods presented have been reflected in the consolidated financial statements. The results of operations of any interim period are not necessarily indicative of the results of operations for the full annual period or any future period due to seasonal and other factors. Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires the Company to make estimates and judgments that affect the amounts reported and disclosed in the consolidated financial statements and accompanying notes. Actual results could differ from these estimates and judgments. The accounting estimates that require management’s most subjective judgments include: stock-based compensation; income taxes, including the estimate of the annual effective tax rate at interim periods and evaluation of uncertain tax positions; and valuation of goodwill and intangible assets. As of March 31, 2021, the effects of the ongoing COVID-19 pandemic on our business, results of operations, and financial condition continue to evolve. A s a result, many of the Company’s estimates and judgments required increased judgment and carry a higher degree of variability and volatility. As additional information becomes available, the Company’s estimates may change materially in future periods. Stock-Based Compensation Service based stock options, service based restricted stock units (“RSUs”), and performance based restricted stock units (“PBRSUs”), are awarded to employees, officers, and members of the Company’s Board of Directors. The PBRSUs include financial performance based restricted stock units (“Financial PBRSUs”) and total shareholder return performance based restricted stock units (“TSR PBRSUs”), both of which have performance and service vesting requirements. The Company recognizes forfeitures as they occur. The fair value of the stock options and RSUs are measured using the closing price of the Company’s common stock on Nasdaq on the grant date. Additionally, the fair value of the Financial PBRSUs are determined using a probability assessment and the fair value of the TSR PBRSUs with market conditions are determined using the Monte-Carlo simulation model. For PBRSUs, the Company recognizes stock-based compensation expenses on a straight-line basis over the longer of the derived, explicit, or implicit service period. As of interim and annual reporting periods, the Financial PBRSUs stock-based compensation expense is adjusted based on expected achievement of performance targets, while TSR PBRSUs stock-based compensation expense is not adjusted. Recently Adopted Accounting Pronouncements In August 2020, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2020-06— Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity's Own Equity (Subtopic 815-40)—Accounting For Convertible Instruments and Contracts in an Entity's Own Equity (“ASU 2020-06”). ASU 2020-06 simplifies accounting for convertible instruments by removing major separation models previously required under GAAP. Consequently, more convertible debt instruments will be reported as a single liability instrument with no separate accounting for embedded conversion features through equity. Without an initial allocation of proceeds to the conversion option, the debt will likely have a lower discount, thereby resulting in less non-cash interest expense through accretion. ASU 2020-06 removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception, which will permit more equity contracts to qualify for it. ASU 2020-06 also simplifies the diluted net income per share calculation in certain areas. The new guidance is effective for annual and interim periods beginning after December 15, 2021, and early adoption is permitted for fiscal years beginning after December 15, 2020, and interim periods within those fiscal years. This update permits the use of either the modified retrospective or fully retrospective method of transition. The Company early adopted this standard, effective as of January 1, 2021, on a modified retrospective basis. The adoption of this standard had a material effect on the Company’s consolidated financial statements. The most significant effects related to the 0.125% Convertible Senior Notes due 2027 (the “2020 Notes”), 0.125% Convertible Senior Notes due 2026 (the “2019 Notes”), and 0% Convertible Senior Notes due 2023 (the “2018 Notes” and together with the 2020 Notes and the 2019 Notes, the “Notes”), and included derecognition of the unamortized debt discount, which was recorded as a direct deduction from the Notes, resulting in an increase in long-term debt, net of approximately $264 million; derecognition of the equity component, which represents the value of the conversion option on the issuance date of the Notes outstanding, resulting in a reduction in additional paid-in capital of approximately $229 million, net of taxes; derecognition of deferred tax liabilities of approximately $63 million; and reversal of the cumulative debt discount recognized as interest expense in the Company’s Consolidated Statements of Operations since the date of issuance of each of the Notes to the period ending December 31, 2020, resulting in a decrease of accumulated deficit of approximately $28 million, net of taxes. The Company also had a reduction in interest expense due to the adoption of ASU 2020-06 as the debt discount has been derecognized and, effective January 1, 2021, there is no amortization of the debt discount. The Company did not incur any impact to liquidity or cash flows. When calculating net income per share of common stock attributable to common stockholders, the Company uses the if-converted method as required under ASU 2020-06 to determine the dilutive effect of the Notes.

Revenue

Revenue	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Revenue	Note 2—Revenue The following table summarizes revenue disaggregated by Marketplace revenue and optional Services revenue for the periods presented (in thousands): Three Months Ended 2021 2020 Marketplace revenue $ 413,642 $ 155,921 Services revenue 137,004 72,134 Revenue $ 550,646 $ 228,055 Contract balances Deferred revenues The amount of revenue recognized in the three months ended March 31, 2021 that was included in the deferred balance at January 1, 2021 was $10.8 million.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Note 3—Income Taxes The Company’s provision or benefit from income taxes in interim periods is determined using an estimate of the annual effective tax rate, adjusted for discrete items, if any, that are taken into account in the relevant period. Each quarter the Company updates its estimate of the annual effective tax rate, and if its estimated tax rate changes, the Company makes a cumulative adjustment. The estimate of the annual effective income tax rate for the full year is applied to the respective interim period, taking into account year-to-date amounts and projected results for the full year. The Company’s quarterly tax provision, and its quarterly estimate of the annual effective tax rate, is subject to significant variation due to several factors, including variability in accurately predicting its income or loss before tax and the mix of jurisdictions to which they relate, taxable income or loss in each jurisdiction, changes in its stock price, audit-related developments, acquisitions, changes in its deferred tax assets and liabilities and their valuation, foreign currency gains (losses), changes in statutes, regulations, case law, and administrative practices, principles, and interpretations related to tax, including changes to the global tax framework, competition, and other laws and accounting rules in various jurisdictions, and relative changes of expenses or losses for which tax benefits are not recognized. Additionally, the effective tax rate can be more or less volatile based on the amount of income or loss before tax. For example, the impact of discrete items and non-deductible expenses on the effective tax rate is greater when income before income taxes is lower. For the three months ended March 31, 2021, the Company’s effective income tax rate was 8.9% representing an income tax provision recorded on net income before tax. The effective tax rate for the three months ended March 31, 2021 was lower than the U.S. statutory rate of 21% primarily due to excess tax benefits from employee stock-based compensation, the impact from foreign operations that are subject to lower tax rates, and a benefit related to a research and development tax credit, partially offset by state income taxes. Although management believes its tax positions and related provisions reflected in the consolidated financial statements are fully supportable, it recognizes that these tax positions and related provisions may be challenged by various tax authorities. These tax positions and related provisions are reviewed on an ongoing basis and are adjusted as additional facts and information become available, including progress on tax audits, changes in interpretation of tax laws, developments in case law and closing of statute of limitations. To the extent that the ultimate results differ from the original or adjusted estimates of the Company, the effect will be recorded in the provision for income taxes. The provision for income taxes involves a significant amount of management judgment regarding interpretation of relevant facts and laws in the jurisdictions in which the Company operates. Future changes in applicable laws, projected levels of taxable income and tax planning could change the effective tax rate and tax balances recorded by the Company. In addition, tax authorities periodically review income tax returns filed by the Company and can raise issues regarding its filing positions, timing and amount of income and deductions, and the allocation of income among the jurisdictions in which the Company operates. A significant period of time may elapse between the filing of an income tax return and the ultimate resolution of an issue raised by a revenue authority with respect to that return. Any adjustments as a result of any examination, may result in additional taxes or penalties against the Company. If the ultimate result of these audits differ from original or adjusted estimates, they could have a material impact on the Company’s tax provision. The amount of unrecognized tax benefits included in the Consolidated Balance Sheets increased $1.0 million in the three months ended March 31, 2021, from $23.7 million as of December 31, 2020 to $24.7 million as of March 31, 2021. The total amount of unrecognized tax benefits that, if recognized, would favorably affect the effective tax rate is $23.8 million as of March 31, 2021. Although the timing of the resolution and/or closure of audits is highly uncertain, it is reasonably possible that the balance of gross unrecognized tax benefits could significantly change in the next 12 months. Given the number of years remaining subject to examination and the number of matters being examined, at this time, the Company is unable to estimate the full range of possible adjustments to the balance of gross unrecognized tax benefits.

Net Income Per Share

Net Income Per Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Net Income Per Share	Note 4—Net Income Per Share The following table presents the method used when calculating the impact of the Company’s convertible senior notes on earnings per share for the periods presented: Three Months Ended 2021 2020 2020 Notes If-Converted N/A 2019 Notes If-Converted Treasury Stock 2018 Notes If-Converted If-Converted The Notes were dilutive for the three months ended March 31, 2021. The following table presents the calculation of basic and diluted net income per share for the periods presented (in thousands, except share and per share amounts): Three Months Ended 2021 2020 Numerator: Net income attributable to common stockholders—basic $ 143,766 $ 12,522 Add back interest expense, net of tax attributable to assumed conversion of convertible senior notes 784 — Net income attributable to common stockholders—diluted $ 144,550 $ 12,522 Denominator: Weighted-average common shares outstanding—basic 126,214,735 118,138,186 Dilutive effect of assumed conversion of options to purchase common stock 4,405,537 4,000,177 Dilutive effect of assumed conversion of restricted stock units 2,311,459 980,690 Dilutive effect of assumed conversion of convertible senior notes 11,782,955 — Weighted-average common shares outstanding—diluted 144,714,686 123,119,053 Net income per share attributable to common stockholders—basic $ 1.14 $ 0.11 Net income per share attributable to common stockholders—diluted $ 1.00 $ 0.10 The following potential common shares were excluded from the calculation of diluted net income per share attributable to common stockholders because their effect would have been anti-dilutive for the periods presented: Three Months Ended 2021 2020 Stock options 32,992 624,906 Restricted stock units 114,953 1,144,169 Convertible senior notes — 16,924,593 Total anti-dilutive securities 147,945 18,693,668

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 5—Fair Value Measurements The Company has characterized its investments in marketable securities, based on the priority of the inputs used to value the investments, into a three-level fair value hierarchy. The fair value hierarchy gives the highest priority to quoted prices in active markets for identical assets or liabilities (Level 1), and lowest priority to unobservable inputs (Level 3). If the inputs used to measure the investments fall within different levels of the hierarchy, the categorization is based on the lowest level input that is significant to the fair value measurement of the investment. Investments recorded in the accompanying Consolidated Balance Sheets are categorized based on the inputs to valuation techniques as follows: Level 1—These are investments where values are based on unadjusted quoted prices for identical assets in an active market that the Company has the ability to access. Level 2—These are investments where values are based on quoted market prices in markets that are not active or model derived valuations in which all significant inputs are observable in active markets. Level 3—These are financial instruments where values are derived from techniques in which one or more significant inputs are unobservable. The Company did not have any Level 3 instruments as of March 31, 2021 and December 31, 2020. Short- and long-term investments and certain cash equivalents consist of investments in debt securities. With the exception of money market funds, these investments in debt securities are classified as available-for-sale. The following table sets forth the cost, gross unrealized losses, gross unrealized gains, and fair values of the Company’s investments as of the dates indicated (in thousands): Cost Gross Gross Fair Value Cash and Cash Equivalents Short-term Investments Long-term Investments March 31, 2021 Cash $ 268,843 $ — $ — $ 268,843 $ 268,843 $ — $ — Level 1 Foreign government 5,000 — — 5,000 — 5,000 — U.S. Government and agency securities 351,887 — 282 352,169 — 347,166 5,003 Money market funds (1) 911,563 892,815 — — 356,887 — 282 1,268,732 892,815 352,166 5,003 Level 2 Certificate of deposit 34,951 (1) 10 34,960 — 34,960 — Commercial paper 51,730 (3) 13 51,740 2,020 49,720 — Corporate bonds 198,543 (237) 69 198,375 — 65,723 132,652 285,224 (241) 92 285,075 2,020 150,403 132,652 $ 910,954 $ (241) $ 374 $ 1,822,650 $ 1,163,678 $ 502,569 $ 137,655 December 31, 2020 Cash $ 346,136 $ — $ — $ 346,136 $ 346,136 $ — $ — Level 1 U.S. Government and agency securities 410,371 (3) 358 410,726 — 376,089 34,637 Money market funds (1) 920,643 881,465 — — 410,371 (3) 358 1,331,369 881,465 376,089 34,637 Level 2 Certificate of deposit 12,746 — 5 12,751 6,000 6,751 — Commercial paper 14,494 — 4 14,498 10,498 4,000 — Corporate bonds 42,632 (7) 111 42,736 — 38,279 4,457 69,872 (7) 120 69,985 16,498 49,030 4,457 $ 826,379 $ (10) $ 478 $ 1,747,490 $ 1,244,099 $ 425,119 $ 39,094 (1) $18.7 million and $39.2 million of money market funds were classified as funds receivable and seller accounts as of March 31, 2021 and December 31, 2020, respectively. The Company evaluates fair value for each individual security in the investment portfolio. All investments in an unrealized loss position have been in an unrealized loss position for less than 12 months as of March 31, 2021. The Company typically invests in short- and long-term instruments, including fixed-income funds and U.S. Government and agency securities aligned with our investment strategy. The maturities of the Company’s non-current marketable debt securities generally range from greater than 12 and up to 37 months. Disclosure of Fair Values The Company’s financial instruments that are not measured at fair value in the Consolidated Balance Sheets include the Notes, see “Note 7—Debt.” The Company estimates the fair value of the Notes through inputs that are observable in the market, classified as Level 2 as described above. The following table presents the carrying value and estimated fair value of the Notes as of the dates indicated (in thousands): As of March 31, 2021 As of December 31, 2020 Carrying Value (1) Fair Value Carrying Value Fair Value 2020 Notes $ 642,342 $ 855,530 $ 511,733 $ 536,126 2019 Notes 643,552 1,540,435 514,035 566,399 2018 Notes 16,456 91,346 39,166 42,157 $ 1,302,350 $ 2,487,311 $ 1,064,934 $ 1,144,682 (1) Upon adoption of ASU 2020-06 as of January 1, 2021, the carrying value of the Notes increased due to the derecognition of the unamortized debt discount, as described in “Note 1—Basis of Presentation and Summary of Significant Accounting Policies—Recently Adopted Accounting Pronouncements.” The increase in the carrying value of the 2018 Notes was offset by the conversion of $27.3 million of the 2018 Notes in the first quarter of 2021 (see “Note 7—Debt”). The carrying value of other financial instruments, including cash, accounts receivable, accounts payable, funds receivable and seller accounts, and funds payable and amounts due to sellers approximate fair value due to the immediate or short-term maturity associated with these instruments.

Accrued Expenses

Accrued Expenses	3 Months Ended
	Mar. 31, 2021
Payables and Accruals [Abstract]
Accrued Expenses	Note 6—Accrued Expenses Accrued expenses consisted of the following as of the dates indicated (in thousands): As of March 31, As of December 31, Pass-through marketplace tax collection obligation $ 103,191 $ 109,662 Vendor accruals 77,094 73,437 Employee compensation-related liabilities 18,207 43,879 Income tax payable 19,665 5,374 Total accrued expenses $ 218,157 $ 232,352

Debt

Debt	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Debt	Note 7—Debt 2020 Convertible Debt In August 2020, the Company issued $650.0 million aggregate principal amount of the 2020 Notes in a private placement to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, as amended (the “Securities Act”). The net proceeds from the sale of the 2020 Notes were approximately $639.5 million after deducting the offering expenses. The 2020 Notes are convertible into shares of the Company’s common stock based upon an initial conversion rate of 5.0007 shares of the Company’s common stock per $1,000 principal amount of 2020 Notes (equivalent to an initial conversion price of approximately $199.97 per share). The Company used $74.7 million of the net proceeds from the 2020 Notes offering to enter into separate capped call instruments (“2020 Capped Call Transactions”) with the initial purchasers and/or their respective affiliates. During any calendar quarter preceding May 1, 2027 in which the closing price of the Company’s common stock exceeds 130% of the applicable conversion price of the 2020 Notes on at least 20 of the last 30 consecutive trading days of the quarter, holders may, in the immediate quarter following, convert all or a portion of their 2020 Notes. Based on the daily closing prices of the Company’s stock during the quarter ended March 31, 2021, holders of the 2020 Notes are not eligible to convert their 2020 Notes during the second quarter of 2021. Based on the terms of the 2020 Notes, when a conversion notice is received, the Company has the option to pay or deliver cash, shares of the Company’s common stock, or a combination thereof. Accordingly, the Company cannot be required to settle the 2020 Notes in cash and, therefore, the 2020 Notes are classified as long-term debt as of March 31, 2021. 2019 Convertible Debt In September 2019, the Company issued $650.0 million aggregate principal amount of the 2019 Notes in a private placement to qualified institutional buyers pursuant to Rule 144A under the Securities Act. The net proceeds from the sale of the 2019 Notes were $639.5 million after deducting the initial purchasers’ discount and offering expenses. The 2019 Notes are convertible based upon an initial conversion rate of 11.4040 shares of the Company’s common stock per $1,000 principal amount of 2019 Notes (equivalent to an initial conversion price of approximately $87.69 per share). The Company used $76.2 million of the net proceeds from the 2019 Notes offering to enter into separate capped call instruments (“2019 Capped Call Transactions”) with the initial purchasers and/or their respective affiliates. During any calendar quarter preceding June 1, 2026 in which the closing price of the Company’s common stock exceeds 130% of the applicable conversion price of the 2019 Notes on at least 20 of the last 30 consecutive trading days of the quarter, holders may, in the immediate quarter following, convert all or a portion of their 2019 Notes. Based on the daily closing prices of the Company’s stock during the quarter ended March 31, 2021, holders of the 2019 Notes are eligible to convert their 2019 Notes during the second quarter of 2021. Based on the terms of the 2019 Notes, when a conversion notice is received, the Company has the option to pay or deliver cash, shares of the Company’s common stock, or a combination thereof. Accordingly, the Company cannot be required to settle the 2019 Notes in cash and, therefore, the 2019 Notes are classified as long-term debt as of March 31, 2021. 2018 Convertible Debt In March 2018, the Company issued $345.0 million aggregate principal amount of the 2018 Notes in a private placement to qualified institutional buyers pursuant to Rule 144A under the Securities Act. The net proceeds from the sale of the 2018 Notes were $335.0 million after deducting the initial purchasers’ discount and offering expenses. The 2018 Notes are convertible based upon an initial conversion rate of 27.5691 shares of the Company’s common stock per $1,000 principal amount of 2018 Notes (equivalent to an initial conversion price of approximately $36.27 per share). The Company used $34.2 million of the net proceeds from the 2018 Notes offering to enter into separate capped call instruments (“2018 Capped Call Transactions”) with the initial purchasers and/or their respective affiliates. During the third quarter of 2020, the Company paid $137.2 million in cash and issued approximately 7.3 million shares of Etsy’s common stock to repurchase $301.1 million aggregate principal amount of its outstanding 2018 Notes through privately negotiated transactions. Concurrently, the Company repurchased 1.3 million shares of Etsy’s common stock for $166.2 million, in order to effectively complete the partial repurchase of 2018 Notes principal value in cash, and the conversion premium in shares. The equity component impact associated with the conversion premium on the 2018 Notes was a net increase to additional paid-in capital of $143.2 million. This transaction was accounted for as an extinguishment of debt and recorded in accordance with the applicable accounting standard in the year ended December 31, 2020. The Company recognized a non-cash loss on extinguishment of $16.9 million. This loss was calculated by comparing the carrying value of the debt component with the fair value of a similar liability that does not have an associated convertible feature immediately prior to extinguishment as well as writing off any remaining unamortized deferred debt issuance costs at the time of extinguishment. During the first quarter of 2021, the Company paid $27.3 million in cash and issued approximately 0.6 million shares of Etsy’s common stock to settle conversion notices of $27.3 million aggregate principal amount of the outstanding 2018 Notes. The debt conversion transaction was accounted for in accordance with ASU 2020-06, which was adopted in the first quarter of 2021. See “Note 1—Basis of Presentation and Summary of Significant Accounting Policies—Recently Adopted Accounting Pronouncements” for additional information. During any calendar quarter preceding November 1, 2022 in which the closing price of the Company’s common stock exceeds 130% of the applicable conversion price of the 2018 Notes on at least 20 of the last 30 consecutive trading days of the quarter, holders may, in the immediate quarter following, convert all or a portion of their 2018 Notes. Based on the daily closing prices of the Company’s stock during the quarter ended March 31, 2021, holders of the remaining 2018 Notes are eligible to convert their 2018 Notes during the second quarter of 2021. Based on the terms of the 2018 Notes, when a conversion notice is received, the Company has the option to pay or deliver cash, shares of the Company’s common stock, or a combination thereof. Accordingly, the Company cannot be required to settle the 2018 Notes in cash and, therefore, the remaining 2018 Notes are classified as long-term debt as of March 31, 2021. The following table presents the outstanding principal amount and carrying value of the Notes as of the dates indicated (in thousands): As of March 31, 2021 2020 Notes 2019 Notes 2018 Notes Total Principal $ 650,000 $ 650,000 $ 16,599 $ 1,316,599 Unamortized debt issuance costs 7,658 6,448 143 14,249 Net carrying value (1) $ 642,342 $ 643,552 $ 16,456 $ 1,302,350 As of December 31, 2020 2020 Notes 2019 Notes 2018 Notes Total Principal $ 650,000 $ 650,000 $ 43,915 $ 1,343,915 Unamortized debt discount (1) 130,308 129,224 4,286 263,818 Unamortized debt issuance costs 7,959 6,741 463 15,163 Net carrying value $ 511,733 $ 514,035 $ 39,166 $ 1,064,934 (1) Upon adoption of ASU 2020-06 as of January 1, 2021, the unamortized debt discount balance was derecognized, as described in “Note 1—Basis of Presentation and Summary of Significant Accounting Policies—Recently Adopted Accounting Pronouncements.” The effective interest rate for the 2020 Notes, 2019 Notes, and 2018 Notes at the date of issuance was 3.50%, 4.00%, and 4.75%, respectively. Interest expense related to each of the Notes for the periods presented below was as follows (in thousands): Three Months Ended 2021 2020 2020 Notes 2019 Notes 2018 Notes Total 2020 Notes 2019 Notes 2018 Notes Total Coupon interest and amortization of debt issuance costs $ 502 $ 496 $ 32 $ 1,030 $ — $ 456 $ 382 $ 838 Amortization of debt discount (1) — — — — — 4,828 3,540 8,368 Total interest expense $ 502 $ 496 $ 32 $ 1,030 $ — $ 5,284 $ 3,922 $ 9,206 (1) The decrease in interest expense related to the amortization of the debt discount in the current year is due to the adoption of ASU 2020-06 as of January 1, 2021, as described in “Note 1—Basis of Presentation and Summary of Significant Accounting Policies—Recently Adopted Accounting Pronouncements.” The estimated fair value of each of the Notes was determined through inputs that are observable in the market, and are classified as Level 2. See “Note 5—Fair Value Measurements” for more information regarding the fair value of the Notes. The Notes are general unsecured obligations of the Company. The Notes rank senior in right of payment to all of the Company’s future indebtedness that is expressly subordinated in right of payment to the Notes; rank equal in right of payment with all of the Company’s liabilities that are not so subordinated; are effectively junior to any of the Company’s secured indebtedness; and are structurally junior to all indebtedness and liabilities (including trade payables) of the Company’s subsidiaries. 2019 Credit Agreement On February 25, 2019, the Company entered into a $200.0 million senior secured revolving credit facility pursuant to a Credit Agreement (the “2019 Credit Agreement”) with lenders party thereto from time to time, and Citibank N.A., as administrative Agent. The 2019 Credit Agreement will mature in February 2024. The 2019 Credit Agreement includes a letter of credit sublimit of $30.0 million and a swingline loan sublimit of $10.0 million. Borrowings under the 2019 Credit Agreement (other than swingline loans) bear interest, at the Company’s option, at (i) a base rate equal to the highest of (a) the prime rate, (b) the federal funds rate plus 0.50%, and (c) an adjusted LIBOR rate for a one-month interest period plus 1.00%, in each case plus a margin ranging from 0.25% to 0.875% or (ii) an adjusted LIBOR rate plus a margin ranging from 1.25% to 1.875%. Swingline loans under the 2019 Credit Agreement bear interest at the same base rate (plus the margin applicable to borrowings bearing interest at the base rate). These margins are determined based on the senior secured net leverage ratio (defined as secured funded debt, net of unrestricted cash up to $100 million, to EBITDA) for the preceding four fiscal quarter period. The Company is also obligated to pay other customary fees for a credit facility of this size and type, including an unused commitment fee, ranging from 0.20% to 0.35% depending on the Company’s senior secured net leverage ratio, and fees associated with letters of credit.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 8—Commitments and Contingencies Legal Proceedings From time to time in the normal course of business, various other claims and litigation have been asserted or commenced against the Company. Due to uncertainties inherent in litigation and other claims, the Company can give no assurance that it will prevail in any such matters, which could subject the Company to significant liability for damages. Any claims or litigation could have an adverse effect on the Company’s results of operations, cash flows, or business and financial condition in the period the claims or litigation are resolved. Although the results of litigation and claims cannot be predicted with certainty, the Company currently believes that the final outcome of these ordinary course matters will not have a material adverse effect on its business.

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Stockholders' Equity	Note 9—Stockholders’ Equity In December 2020, the Board of Directors approved a stock repurchase program that enables the Company to repurchase up to $250 million of its common stock. The program does not have a time limit and may be modified, suspended, or terminated at any time by the Board of Directors. The number of shares repurchased and the timing of repurchases will depend on a number of factors, including, but not limited to, stock price, trading volume, and general market conditions, along with Etsy’s working capital requirements, general business conditions, and other factors. Under the stock repurchase program, the Company may purchase shares of its common stock through various means, including open market transactions, privately negotiated transactions, tender offers, or any combination thereof. In addition, open market repurchases of common stock could be made pursuant to trading plans established pursuant to Rule 10b5-1 under the Securities Exchange Act of 1934, as amended, which would permit common stock to be repurchased at a time that the Company might otherwise be precluded from doing so under insider trading laws or self-imposed trading restrictions. For the three months ended March 31, 2021, the Company did not repurchase common stock under the stock repurchase program, and the remaining amount authorized as of March 31, 2021 is $250 million.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Note 10—Stock-Based Compensation During the three months ended March 31, 2021, the Company granted stock options and RSUs, including Financial PBRSUs and TSR PBRSUs, under its 2015 Equity Incentive Plan (“2015 Plan”) and, pursuant to the evergreen increase provision of the 2015 Plan, the Board of Directors approved an increase of 6,291,797 shares to the total number of shares available for issuance under the 2015 Plan effective as of January 4, 2021. At March 31, 2021, 44,040,744 shares were authorized under the 2015 Plan and 30,272,377 shares were available for future grant. The fair value of options granted in the periods presented below using the Black-Scholes pricing model has been based on the following assumptions: Three Months Ended 2021 2020 Volatility 43.4% 39.5% Risk-free interest rate 1.1% 0.6% - 1.7% Expected term (in years) 6.15 6.15 The following table summarizes the activity for the Company’s options during the three months ended March 31, 2021 (in thousands, except share and per share amounts): Shares Weighted-Average Exercise Price Weighted-Average Remaining Contract Term (in years) Aggregate Intrinsic Value Outstanding at December 31, 2020 5,099,952 $ 20.97 6.81 $ 800,453 Granted 174,663 223.23 Exercised (217,293) 18.08 Forfeited/Canceled (9,547) 49.36 Outstanding at March 31, 2021 5,047,775 28.04 6.70 $ 880,289 Total exercisable at March 31, 2021 3,656,240 14.02 6.10 686,096 The following table summarizes the weighted-average grant date fair value of options granted, intrinsic value of options exercised, and fair value of awards vested during the three months ended March 31, 2021 and 2020 (in thousands, except per share amounts): Three Months Ended 2021 2020 Weighted-average grant date fair value of options granted $ 95.71 $ 16.68 Intrinsic value of options exercised 44,354 20,425 Fair value of awards vested 8,976 7,385 The total unrecognized compensation expense at March 31, 2021 related to the Company’s options was $33.0 million, which will be recognized over an estimated weighted-average amortization period of 3.18 years. During the first quarter of 2021, service based RSUs, Financial PBRSUs, and TSR PBRSUs were awarded at fixed dollar amounts. The target number of shares underlying the awards was determined based on Etsy’s 30-day average share price leading up to and including the grant date. For the Financial PBRSUs, the number of RSUs received will depend on the achievement of financial metrics relative to the approved performance targets. Depending on the actual financial metrics achieved relative to the target financial metrics, the number of PBRSUs issued could range from 0% to 200% of the target amount. For the TSR PBRSUs, the number of RSUs received will depend on the Company’s total shareholder return relative to that of the Nasdaq Composite Index over a three-year measurement period. The target number of RSUs will be divided into two tranches, with each tranche corresponding to 50% of the target RSUs. The first tranche will vest in full on the third anniversary of the grant date and the second tranche will vest on the fourth anniversary of the grant date, subject to the Compensation Committee’s approval of the level of achievement against the approved performance targets. The following table summarizes the activity for the Company’s unvested RSUs, which includes Financial PBRSUs and TSR PBRSUs, during the three months ended March 31, 2021: Shares Weighted-Average Unvested at December 31, 2020 3,085,987 $ 50.28 Granted 791,938 228.36 Vested (183,098) 37.90 Forfeited/Canceled (40,930) 68.80 Unvested at March 31, 2021 3,653,897 89.29 The total unrecognized compensation expense at March 31, 2021 related to the Company’s unvested RSUs, including the Financial PBRSUs and TSR PBRSUs, was $296.5 million, which will be recognized over an estimated weighted-average amortization period of 3.35 years. Stock-based compensation expense included in the Consolidated Statements of Operations for the periods presented below is as follows (in thousands): Three Months Ended 2021 2020 Cost of revenue $ 2,357 $ 1,620 Marketing 1,367 1,224 Product development 9,784 6,801 General and administrative 6,843 4,166 Stock-based compensation expense $ 20,351 $ 13,811

Basis of Presentation and Sum_2

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Consolidation	Basis of Consolidation The consolidated financial statements include the accounts of Etsy and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.
Basis of Presentation	Basis of Presentation The accompanying unaudited interim consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and pursuant to the applicable rules and regulations of the Securities and Exchange Commission (“SEC”). The Company has condensed or omitted certain information and notes normally included in complete annual financial statements prepared in accordance with GAAP. These unaudited interim consolidated financial statements should therefore be read in conjunction with the audited consolidated financial statements and accompanying notes included in the Company’s Annual Report on Form 10-K filed with the SEC on February 26, 2021 (the “Annual Report”). In the opinion of management, all material adjustments, which are of a normal and recurring nature, necessary for a fair presentation of the results for the periods presented have been reflected in the consolidated financial statements. The results of operations of any interim period are not necessarily indicative of the results of operations for the full annual period or any future period due to seasonal and other factors.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires the Company to make estimates and judgments that affect the amounts reported and disclosed in the consolidated financial statements and accompanying notes. Actual results could differ from these estimates and judgments. The accounting estimates that require management’s most subjective judgments include: stock-based compensation; income taxes, including the estimate of the annual effective tax rate at interim periods and evaluation of uncertain tax positions; and valuation of goodwill and intangible assets. As of March 31, 2021, the effects of the ongoing COVID-19 pandemic on our business, results of operations, and financial condition continue to evolve. A s a result, many of the Company’s estimates and judgments required increased judgment and carry a higher degree of variability and volatility. As additional information becomes available, the Company’s estimates may change materially in future periods.
Stock-Based Compensation	Stock-Based Compensation Service based stock options, service based restricted stock units (“RSUs”), and performance based restricted stock units (“PBRSUs”), are awarded to employees, officers, and members of the Company’s Board of Directors. The PBRSUs include financial performance based restricted stock units (“Financial PBRSUs”) and total shareholder return performance based restricted stock units (“TSR PBRSUs”), both of which have performance and service vesting requirements. The Company recognizes forfeitures as they occur. The fair value of the stock options and RSUs are measured using the closing price of the Company’s common stock on Nasdaq on the grant date. Additionally, the fair value of the Financial PBRSUs are determined using a probability assessment and the fair value of the TSR PBRSUs with market conditions are determined using the Monte-Carlo simulation model.
Recently Issued and Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In August 2020, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2020-06— Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity's Own Equity (Subtopic 815-40)—Accounting For Convertible Instruments and Contracts in an Entity's Own Equity (“ASU 2020-06”). ASU 2020-06 simplifies accounting for convertible instruments by removing major separation models previously required under GAAP. Consequently, more convertible debt instruments will be reported as a single liability instrument with no separate accounting for embedded conversion features through equity. Without an initial allocation of proceeds to the conversion option, the debt will likely have a lower discount, thereby resulting in less non-cash interest expense through accretion. ASU 2020-06 removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception, which will permit more equity contracts to qualify for it. ASU 2020-06 also simplifies the diluted net income per share calculation in certain areas. The new guidance is effective for annual and interim periods beginning after December 15, 2021, and early adoption is permitted for fiscal years beginning after December 15, 2020, and interim periods within those fiscal years. This update permits the use of either the modified retrospective or fully retrospective method of transition. The Company early adopted this standard, effective as of January 1, 2021, on a modified retrospective basis. The adoption of this standard had a material effect on the Company’s consolidated financial statements. The most significant effects related to the 0.125% Convertible Senior Notes due 2027 (the “2020 Notes”), 0.125% Convertible Senior Notes due 2026 (the “2019 Notes”), and 0% Convertible Senior Notes due 2023 (the “2018 Notes” and together with the 2020 Notes and the 2019 Notes, the “Notes”), and included derecognition of the unamortized debt discount, which was recorded as a direct deduction from the Notes, resulting in an increase in long-term debt, net of approximately $264 million; derecognition of the equity component, which represents the value of the conversion option on the issuance date of the Notes outstanding, resulting in a reduction in additional paid-in capital of approximately $229 million, net of taxes; derecognition of deferred tax liabilities of approximately $63 million; and reversal of the cumulative debt discount recognized as interest expense in the Company’s Consolidated Statements of Operations since the date of issuance of each of the Notes to the period ending December 31, 2020, resulting in a decrease of accumulated deficit of approximately $28 million, net of taxes. The Company also had a reduction in interest expense due to the adoption of ASU 2020-06 as the debt discount has been derecognized and, effective January 1, 2021, there is no amortization of the debt discount. The Company did not incur any impact to liquidity or cash flows. When calculating net income per share of common stock attributable to common stockholders, the Company uses the if-converted method as required under ASU 2020-06 to determine the dilutive effect of the Notes.

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following table summarizes revenue disaggregated by Marketplace revenue and optional Services revenue for the periods presented (in thousands): Three Months Ended 2021 2020 Marketplace revenue $ 413,642 $ 155,921 Services revenue 137,004 72,134 Revenue $ 550,646 $ 228,055

Net Income Per Share (Tables)

Net Income Per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Schedule of Method Used to Calculate Impact from Convertible Senior Notes on Earnings Per Share	The following table presents the method used when calculating the impact of the Company’s convertible senior notes on earnings per share for the periods presented: Three Months Ended 2021 2020 2020 Notes If-Converted N/A 2019 Notes If-Converted Treasury Stock 2018 Notes If-Converted If-Converted
Schedule of Calculation of Basic and Diluted Net Income Per Share	The following table presents the calculation of basic and diluted net income per share for the periods presented (in thousands, except share and per share amounts): Three Months Ended 2021 2020 Numerator: Net income attributable to common stockholders—basic $ 143,766 $ 12,522 Add back interest expense, net of tax attributable to assumed conversion of convertible senior notes 784 — Net income attributable to common stockholders—diluted $ 144,550 $ 12,522 Denominator: Weighted-average common shares outstanding—basic 126,214,735 118,138,186 Dilutive effect of assumed conversion of options to purchase common stock 4,405,537 4,000,177 Dilutive effect of assumed conversion of restricted stock units 2,311,459 980,690 Dilutive effect of assumed conversion of convertible senior notes 11,782,955 — Weighted-average common shares outstanding—diluted 144,714,686 123,119,053 Net income per share attributable to common stockholders—basic $ 1.14 $ 0.11 Net income per share attributable to common stockholders—diluted $ 1.00 $ 0.10
Schedule of Anti-Dilutive Securities Excluded from Computation of Net Income Per Share	The following potential common shares were excluded from the calculation of diluted net income per share attributable to common stockholders because their effect would have been anti-dilutive for the periods presented: Three Months Ended 2021 2020 Stock options 32,992 624,906 Restricted stock units 114,953 1,144,169 Convertible senior notes — 16,924,593 Total anti-dilutive securities 147,945 18,693,668

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Schedule of Fair Values Company’s Investments	The following table sets forth the cost, gross unrealized losses, gross unrealized gains, and fair values of the Company’s investments as of the dates indicated (in thousands): Cost Gross Gross Fair Value Cash and Cash Equivalents Short-term Investments Long-term Investments March 31, 2021 Cash $ 268,843 $ — $ — $ 268,843 $ 268,843 $ — $ — Level 1 Foreign government 5,000 — — 5,000 — 5,000 — U.S. Government and agency securities 351,887 — 282 352,169 — 347,166 5,003 Money market funds (1) 911,563 892,815 — — 356,887 — 282 1,268,732 892,815 352,166 5,003 Level 2 Certificate of deposit 34,951 (1) 10 34,960 — 34,960 — Commercial paper 51,730 (3) 13 51,740 2,020 49,720 — Corporate bonds 198,543 (237) 69 198,375 — 65,723 132,652 285,224 (241) 92 285,075 2,020 150,403 132,652 $ 910,954 $ (241) $ 374 $ 1,822,650 $ 1,163,678 $ 502,569 $ 137,655 December 31, 2020 Cash $ 346,136 $ — $ — $ 346,136 $ 346,136 $ — $ — Level 1 U.S. Government and agency securities 410,371 (3) 358 410,726 — 376,089 34,637 Money market funds (1) 920,643 881,465 — — 410,371 (3) 358 1,331,369 881,465 376,089 34,637 Level 2 Certificate of deposit 12,746 — 5 12,751 6,000 6,751 — Commercial paper 14,494 — 4 14,498 10,498 4,000 — Corporate bonds 42,632 (7) 111 42,736 — 38,279 4,457 69,872 (7) 120 69,985 16,498 49,030 4,457 $ 826,379 $ (10) $ 478 $ 1,747,490 $ 1,244,099 $ 425,119 $ 39,094 (1) $18.7 million and $39.2 million of money market funds were classified as funds receivable and seller accounts as of March 31, 2021 and December 31, 2020, respectively.
Schedule of Estimated Fair Value Liability Component	The following table presents the carrying value and estimated fair value of the Notes as of the dates indicated (in thousands): As of March 31, 2021 As of December 31, 2020 Carrying Value (1) Fair Value Carrying Value Fair Value 2020 Notes $ 642,342 $ 855,530 $ 511,733 $ 536,126 2019 Notes 643,552 1,540,435 514,035 566,399 2018 Notes 16,456 91,346 39,166 42,157 $ 1,302,350 $ 2,487,311 $ 1,064,934 $ 1,144,682 (1) Upon adoption of ASU 2020-06 as of January 1, 2021, the carrying value of the Notes increased due to the derecognition of the unamortized debt discount, as described in “Note 1—Basis of Presentation and Summary of Significant Accounting Policies—Recently Adopted Accounting Pronouncements.” The increase in the carrying value of the 2018 Notes was offset by the conversion of $27.3 million of the 2018 Notes in the first quarter of 2021 (see “Note 7—Debt”).

Accrued Expenses (Tables)

Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2021
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued expenses consisted of the following as of the dates indicated (in thousands): As of March 31, As of December 31, Pass-through marketplace tax collection obligation $ 103,191 $ 109,662 Vendor accruals 77,094 73,437 Employee compensation-related liabilities 18,207 43,879 Income tax payable 19,665 5,374 Total accrued expenses $ 218,157 $ 232,352

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Schedule of Debt	The following table presents the outstanding principal amount and carrying value of the Notes as of the dates indicated (in thousands): As of March 31, 2021 2020 Notes 2019 Notes 2018 Notes Total Principal $ 650,000 $ 650,000 $ 16,599 $ 1,316,599 Unamortized debt issuance costs 7,658 6,448 143 14,249 Net carrying value (1) $ 642,342 $ 643,552 $ 16,456 $ 1,302,350 As of December 31, 2020 2020 Notes 2019 Notes 2018 Notes Total Principal $ 650,000 $ 650,000 $ 43,915 $ 1,343,915 Unamortized debt discount (1) 130,308 129,224 4,286 263,818 Unamortized debt issuance costs 7,959 6,741 463 15,163 Net carrying value $ 511,733 $ 514,035 $ 39,166 $ 1,064,934 (1) Upon adoption of ASU 2020-06 as of January 1, 2021, the unamortized debt discount balance was derecognized, as described in “Note 1—Basis of Presentation and Summary of Significant Accounting Policies—Recently Adopted Accounting Pronouncements.”
Schedule of Interest Expense	Interest expense related to each of the Notes for the periods presented below was as follows (in thousands): Three Months Ended 2021 2020 2020 Notes 2019 Notes 2018 Notes Total 2020 Notes 2019 Notes 2018 Notes Total Coupon interest and amortization of debt issuance costs $ 502 $ 496 $ 32 $ 1,030 $ — $ 456 $ 382 $ 838 Amortization of debt discount (1) — — — — — 4,828 3,540 8,368 Total interest expense $ 502 $ 496 $ 32 $ 1,030 $ — $ 5,284 $ 3,922 $ 9,206

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Schedule of Black-Scholes Valuation Assumptions Used to Determine Fair Value of Options Granted	The fair value of options granted in the periods presented below using the Black-Scholes pricing model has been based on the following assumptions: Three Months Ended 2021 2020 Volatility 43.4% 39.5% Risk-free interest rate 1.1% 0.6% - 1.7% Expected term (in years) 6.15 6.15
Summary of Stock Option Activity	The following table summarizes the activity for the Company’s options during the three months ended March 31, 2021 (in thousands, except share and per share amounts): Shares Weighted-Average Exercise Price Weighted-Average Remaining Contract Term (in years) Aggregate Intrinsic Value Outstanding at December 31, 2020 5,099,952 $ 20.97 6.81 $ 800,453 Granted 174,663 223.23 Exercised (217,293) 18.08 Forfeited/Canceled (9,547) 49.36 Outstanding at March 31, 2021 5,047,775 28.04 6.70 $ 880,289 Total exercisable at March 31, 2021 3,656,240 14.02 6.10 686,096
Summary of Weighted Average Grant Date Fair Value and Fair Value of Awards Vested	The following table summarizes the weighted-average grant date fair value of options granted, intrinsic value of options exercised, and fair value of awards vested during the three months ended March 31, 2021 and 2020 (in thousands, except per share amounts): Three Months Ended 2021 2020 Weighted-average grant date fair value of options granted $ 95.71 $ 16.68 Intrinsic value of options exercised 44,354 20,425 Fair value of awards vested 8,976 7,385
Summary of Unvested RSU Activity	The following table summarizes the activity for the Company’s unvested RSUs, which includes Financial PBRSUs and TSR PBRSUs, during the three months ended March 31, 2021: Shares Weighted-Average Unvested at December 31, 2020 3,085,987 $ 50.28 Granted 791,938 228.36 Vested (183,098) 37.90 Forfeited/Canceled (40,930) 68.80 Unvested at March 31, 2021 3,653,897 89.29
Schedule of Stock-Based Compensation Expense	Stock-based compensation expense included in the Consolidated Statements of Operations for the periods presented below is as follows (in thousands): Three Months Ended 2021 2020 Cost of revenue $ 2,357 $ 1,620 Marketing 1,367 1,224 Product development 9,784 6,801 General and administrative 6,843 4,166 Stock-based compensation expense $ 20,351 $ 13,811

Basis of Presentation and Sum_3

Basis of Presentation and Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Jan. 01, 2021	Dec. 31, 2020	Aug. 31, 2020	Sep. 30, 2019	Mar. 31, 2018
Reclassification [Line Items]
Increase in long-term debt, net	$ 1,302,345		$ 1,062,299
Reduction in additional paid in capital	(664,240)		(883,166)
Reduction in deferred tax liabilities	(33)		(58,481)
Decrease in accumulated deficit	24,775		(146,819)
Accounting Standards Update 2020-06
Reclassification [Line Items]
Increase in long-term debt, net		$ 264,000
Reduction in additional paid in capital		229,000
Reduction in deferred tax liabilities		63,000
Decrease in accumulated deficit		$ 28,000
Convertible Debt
Reclassification [Line Items]
Increase in long-term debt, net	1,302,350		1,064,934
Convertible Senior Notes Due 2027 | Convertible Debt
Reclassification [Line Items]
Debt instrument, interest rate, stated percentage				0.125%
Increase in long-term debt, net	642,342		511,733
Convertible Senior Notes Due 2026 | Convertible Debt
Reclassification [Line Items]
Debt instrument, interest rate, stated percentage					0.125%
Increase in long-term debt, net	643,552		514,035
Convertible Senior Notes Due 2023 | Convertible Debt
Reclassification [Line Items]
Debt instrument, interest rate, stated percentage						0.00%
Increase in long-term debt, net	$ 16,456		$ 39,166

Revenue - Summary of Revenue by

Revenue - Summary of Revenue by Type (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue	$ 550,646	$ 228,055
Marketplace revenue
Disaggregation of Revenue [Line Items]
Revenue	413,642	155,921
Services revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 137,004	$ 72,134

Revenue - Narrative (Details)

Revenue - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)
Revenue from Contract with Customer [Abstract]
Revenue recognized in the period	$ 10.8

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Effective income tax rate	8.90%
Unrecognized tax benefits, period increase (decrease)	$ 1
Unrecognized tax benefits	24.7	$ 23.7
Unrecognized tax benefits that would impact effective tax rate favorably	$ 23.8

Net Income Per Share - Calculat

Net Income Per Share - Calculation of Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator:
Net income attributable to common stockholders—basic	$ 143,766	$ 12,522
Add back interest expense, net of tax attributable to assumed conversion of convertible senior notes	784	0
Net income attributable to common stockholders—diluted	$ 144,550	$ 12,522
Denominator:
Weighted average common shares outstanding—basic (in shares)	126,214,735	118,138,186
Dilutive effect of assumed conversion of convertible senior notes (in shares)	11,782,955	0
Weighted average common shares outstanding - diluted (in shares)	144,714,686	123,119,053
Net income per share attributable to common stockholders—basic (in dollars per shares)	$ 1.14	$ 0.11
Net income per share attributable to common stockholders—diluted (in dollars per share)	$ 1	$ 0.10
Stock options
Denominator:
Dilutive effect of assumed conversion (in shares)	4,405,537	4,000,177
Restricted stock units
Denominator:
Dilutive effect of assumed conversion (in shares)	2,311,459	980,690

Net Income Per Share - Summary

Net Income Per Share - Summary of Shares Excluded from the Calculation of Diluted Net Income Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share (in shares)	147,945	18,693,668
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share (in shares)	32,992	624,906
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share (in shares)	114,953	1,144,169
Convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share (in shares)	0	16,924,593

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Values Company’s Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cost	$ 910,954	$ 826,379
Gross Unrealized Holding Loss	(241)	(10)
Gross Unrealized Holding Gain	374	478
Fair Value	1,822,650	1,747,490
Cash and Cash Equivalents	1,163,678	1,244,099
Short-term investments	502,569	425,119
Long-term investments	137,655	39,094
Cash
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cost	268,843	346,136
Gross Unrealized Holding Loss	0	0
Gross Unrealized Holding Gain	0	0
Fair Value	268,843	346,136
Cash and Cash Equivalents	268,843	346,136
Short-term investments	0	0
Long-term investments	0	0
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cost	356,887	410,371
Gross Unrealized Holding Loss	0	(3)
Gross Unrealized Holding Gain	282	358
Fair Value	1,268,732	1,331,369
Cash and Cash Equivalents	892,815	881,465
Short-term investments	352,166	376,089
Long-term investments	5,003	34,637
Level 1 | Foreign government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cost	5,000
Gross Unrealized Holding Loss	0
Gross Unrealized Holding Gain	0
Fair Value	5,000
Cash and Cash Equivalents	0
Short-term investments	5,000
Long-term investments	0
Level 1 | U.S. Government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cost	351,887	410,371
Gross Unrealized Holding Loss	0	(3)
Gross Unrealized Holding Gain	282	358
Fair Value	352,169	410,726
Cash and Cash Equivalents	0	0
Short-term investments	347,166	376,089
Long-term investments	5,003	34,637
Level 1 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	911,563	920,643
Cash and Cash Equivalents	892,815	881,465
Short-term investments	0	0
Long-term investments	0	0
Funds receivable and seller accounts	18,700	39,200
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cost	285,224	69,872
Gross Unrealized Holding Loss	(241)	(7)
Gross Unrealized Holding Gain	92	120
Fair Value	285,075	69,985
Cash and Cash Equivalents	2,020	16,498
Short-term investments	150,403	49,030
Long-term investments	132,652	4,457
Level 2 | Certificate of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cost	34,951	12,746
Gross Unrealized Holding Loss	(1)	0
Gross Unrealized Holding Gain	10	5
Fair Value	34,960	12,751
Cash and Cash Equivalents	0	6,000
Short-term investments	34,960	6,751
Long-term investments	0	0
Level 2 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cost	51,730	14,494
Gross Unrealized Holding Loss	(3)	0
Gross Unrealized Holding Gain	13	4
Fair Value	51,740	14,498
Cash and Cash Equivalents	2,020	10,498
Short-term investments	49,720	4,000
Long-term investments	0	0
Level 2 | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cost	198,543	42,632
Gross Unrealized Holding Loss	(237)	(7)
Gross Unrealized Holding Gain	69	111
Fair Value	198,375	42,736
Cash and Cash Equivalents	0	0
Short-term investments	65,723	38,279
Long-term investments	$ 132,652	$ 4,457

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details)	Mar. 31, 2021
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities, investment maturity	37 months
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities, investment maturity	12 months

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Estimated Fair Value Liability Component (Details) - Convertible Debt - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Sep. 30, 2020	Dec. 31, 2020
2018 Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument conversion amount	$ 27,300	$ 301,100
Level 2 | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	1,302,350		$ 1,064,934
Level 2 | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	2,487,311		1,144,682
Level 2 | 2020 Notes | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	642,342		511,733
Level 2 | 2020 Notes | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	855,530		536,126
Level 2 | 2019 Notes | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	643,552		514,035
Level 2 | 2019 Notes | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	1,540,435		566,399
Level 2 | 2018 Notes | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	16,456		39,166
Level 2 | 2018 Notes | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 91,346		$ 42,157

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Pass-through marketplace tax collection obligation	$ 103,191	$ 109,662
Vendor accruals	77,094	73,437
Employee compensation-related liabilities	18,207	43,879
Income tax payable	19,665	5,374
Total accrued expenses	$ 218,157	$ 232,352

Debt - 2020 Convertible Debt (D

Debt - 2020 Convertible Debt (Details) - Convertible Debt $ / shares in Units, $ in Thousands	1 Months Ended
	Aug. 31, 2020USD ($)day$ / shares	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Debt instrument		$ 1,316,599	$ 1,343,915
Convertible Senior Notes Due 2027
Debt Instrument [Line Items]
Debt instrument	$ 650,000	$ 650,000	$ 650,000
Proceeds from issuance of convertible senior notes	$ 639,500
Conversion ratio	0.0050007
Conversion price (in dollars per share) | $ / shares	$ 199.97
Purchase of capped calls	$ 74,700
Convertible Senior Notes Due 2027 | Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Threshold percentage of stock price trigger	130.00%
Threshold trading days | day	20
Threshold consecutive trading days | day	30

Debt - 2019 Convertible Debt (D

Debt - 2019 Convertible Debt (Details) - Convertible Debt $ / shares in Units, $ in Thousands	1 Months Ended
	Sep. 30, 2019USD ($)day$ / shares	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Debt instrument		$ 1,316,599	$ 1,343,915
Convertible Senior Notes Due 2026
Debt Instrument [Line Items]
Debt instrument	$ 650,000	$ 650,000	$ 650,000
Proceeds from issuance of convertible senior notes	$ 639,500
Conversion ratio	0.0114040
Conversion price (in dollars per share) | $ / shares	$ 87.69
Purchase of capped calls	$ 76,200
Threshold percentage of stock price trigger	130.00%
Threshold trading days | day	20
Threshold consecutive trading days | day	30

Debt - 2018 Convertible Debt (D

Debt - 2018 Convertible Debt (Details) $ / shares in Units, $ in Thousands, shares in Millions	1 Months Ended	3 Months Ended
	Mar. 31, 2018USD ($)day$ / shares	Mar. 31, 2021USD ($)shares	Sep. 30, 2020USD ($)shares	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Repayment of convertible senior notes		$ 27,319		$ 0
Shares Repurchased				$ 24,992
Convertible Debt
Debt Instrument [Line Items]
Debt instrument		1,316,599			$ 1,343,915
Convertible Debt | Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Debt instrument	$ 345,000	16,599			$ 43,915
Proceeds from issuance of convertible senior notes	$ 335,000
Conversion ratio	0.0275691
Conversion price (in dollars per share) | $ / shares	$ 36.27
Purchase of capped calls	$ 34,200
Repayment of convertible senior notes		$ 27,300	$ 137,200
Debt instrument conversion amount, shares (in shares) | shares		0.6	7.3
Debt instrument conversion amount		$ 27,300	$ 301,100
Shares Repurchased (in shares) | shares			1.3
Shares Repurchased			$ 166,200
Issuance of convertible senior notes, net of issuance costs and taxes			143,200
Loss on extinguishment of debt			$ 16,900
Threshold percentage of stock price trigger	130.00%
Threshold trading days | day	20
Threshold consecutive trading days | day	30

Debt - Convertible Debt, Schedu

Debt - Convertible Debt, Schedule of Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Aug. 31, 2020	Sep. 30, 2019	Mar. 31, 2018
Debt Instrument [Line Items]
Long-term debt, net	$ 1,302,345	$ 1,062,299
Convertible Debt
Debt Instrument [Line Items]
Principal	1,316,599	1,343,915
Unamortized debt discount		263,818
Unamortized debt issuance costs	14,249	15,163
Long-term debt, net	1,302,350	1,064,934
Convertible Senior Notes Due 2027 | Convertible Debt
Debt Instrument [Line Items]
Principal	650,000	650,000	$ 650,000
Unamortized debt discount		130,308
Unamortized debt issuance costs	7,658	7,959
Long-term debt, net	642,342	511,733
Convertible Senior Notes Due 2026 | Convertible Debt
Debt Instrument [Line Items]
Principal	650,000	650,000		$ 650,000
Unamortized debt discount		129,224
Unamortized debt issuance costs	6,448	6,741
Long-term debt, net	643,552	514,035
Convertible Senior Notes Due 2023 | Convertible Debt
Debt Instrument [Line Items]
Principal	16,599	43,915			$ 345,000
Unamortized debt discount		4,286
Unamortized debt issuance costs	143	463
Long-term debt, net	$ 16,456	$ 39,166

Debt - Convertible Debt, Sche_2

Debt - Convertible Debt, Schedule of Interest Expense (Details) - Convertible Debt - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Aug. 31, 2020	Sep. 30, 2019	Mar. 31, 2018
Debt Instrument [Line Items]
Coupon interest and amortization of debt issuance costs	$ 1,030	$ 838
Amortization of debt discount	0	8,368
Total interest expense	1,030	9,206
Convertible Senior Notes Due 2027
Debt Instrument [Line Items]
Effective interest rate			3.50%
Coupon interest and amortization of debt issuance costs	502	0
Amortization of debt discount	0	0
Total interest expense	502	0
Convertible Senior Notes Due 2026
Debt Instrument [Line Items]
Effective interest rate				4.00%
Coupon interest and amortization of debt issuance costs	496	456
Amortization of debt discount	0	4,828
Total interest expense	496	5,284
Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Effective interest rate					4.75%
Coupon interest and amortization of debt issuance costs	32	382
Amortization of debt discount	0	3,540
Total interest expense	$ 32	$ 3,922

Debt - 2019 Credit Agreement (D

Debt - 2019 Credit Agreement (Details) - Credit Agreement - USD ($)	Feb. 25, 2019	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Line of Credit Facility [Line Items]
Capitalization of debt issuance costs	$ 1,400,000
Unamortized debt issuance costs		$ 800,000		$ 900,000
Non-cash interest expense		100,000	$ 100,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity	200,000,000
Maximum unrestricted cash	$ 100,000,000
Line of credit facility, amount outstanding		$ 0
Revolving Credit Facility | Minimum
Line of Credit Facility [Line Items]
Commitment fee amount	0.20%
Revolving Credit Facility | Maximum
Line of Credit Facility [Line Items]
Commitment fee amount	0.35%
Revolving Credit Facility | Federal Funds Effective Swap Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.50%
Revolving Credit Facility | London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.00%
Revolving Credit Facility | One-Month London Interbank Offered Rate (LIBOR) Plus 1% | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.25%
Revolving Credit Facility | One-Month London Interbank Offered Rate (LIBOR) Plus 1% | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.875%
Revolving Credit Facility | London Interbank Offered Rate (LIBOR), Adjusted | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.25%
Revolving Credit Facility | London Interbank Offered Rate (LIBOR), Adjusted | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.875%
Letter of Credit
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity	$ 30,000,000
Bridge Loan
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity	$ 10,000,000

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Equity [Abstract]
Stock repurchase program, authorized amount		$ 250
Remaining Amount Authorized	$ 250

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details) $ in Millions	Jan. 04, 2021shares	Mar. 31, 2021USD ($)trancheshares
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation | $		$ 33
Total unrecognized compensation, period of recognition		3 years 2 months 4 days
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation, period of recognition		3 years 4 months 6 days
Average share price period		30 days
Total unrecognized compensation | $		$ 296.5
Financial Performance Based Restricted Stock Units (RSUs) | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards that may be issued		0.00%
Financial Performance Based Restricted Stock Units (RSUs) | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards that may be issued		200.00%
Total Shareholder Return Performance Based Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Measurement period		3 years
Performance Based Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of tranches | tranche		2
Share-based compensation arrangement by share-based payment award, percentage		50.00%
2015 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of additional shares issued annually (in shares)	6,291,797
Number of shares authorized (in shares)		44,040,744
Number of shares available for grant (in shares)		30,272,377

Stock-Based Compensation - Fair

Stock-Based Compensation - Fair Value of Options Granted Using the Black-Scholes Pricing Model (Details) - Stock options	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility	43.40%	39.50%
Risk-free interest rate	1.10%
Expected term (in years)	6 years 1 month 24 days	6 years 1 month 24 days
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate		0.60%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate		1.70%

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Shares
Outstanding, beginning balance (in shares)	5,099,952
Granted (in shares)	174,663
Exercised (in shares)	(217,293)
Forfeited/Canceled (in shares)	(9,547)
Outstanding, ending balance (in shares)	5,047,775	5,099,952
Total exercisable (in shares)	3,656,240
Weighted-Average Exercise Price
Outstanding, beginning balance (in dollars per share)	$ 20.97
Granted (in dollars per share)	223.23
Exercised (in dollars per share)	18.08
Forfeited/Canceled (in dollars per share)	49.36
Outstanding, ending balance (in dollars per share)	28.04	$ 20.97
Total exercisable (in dollars per share)	$ 14.02
Weighted-Average Remaining Contract Term (in years)
Outstanding, Weighted-Average Remaining Contractual Term	6 years 8 months 12 days	6 years 9 months 21 days
Total exercisable, Weighted-Average Remaining Contract Term	6 years 1 month 6 days
Aggregate Intrinsic Value
Outstanding, beginning balance	$ 800,453
Outstanding, ending balance	880,289	$ 800,453
Total exercisable, Aggregate Intrinsic Value	$ 686,096

Stock-Based Compensation - Weig

Stock-Based Compensation - Weighted Average Grant Date Fair Value of Options Granted, Intrinsic Value of Options Exercised and Fair Value of Awards Vested (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
Weighted average grant date fair value of options (in dollars per share)	$ 95.71	$ 16.68
Intrinsic value of options exercised	$ 44,354	$ 20,425
Fair value of awards vested	$ 8,976	$ 7,385

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Unvested RSUs (Details) - RSUs	3 Months Ended
	Mar. 31, 2021$ / sharesshares
Shares
Unvested at December 31, 2019 (in shares) | shares	3,085,987
Granted (in shares) | shares	791,938
Vested (in shares) | shares	(183,098)
Forfeited/Cancelled (in shares) | shares	(40,930)
Unvested at September 30, 2020 (in shares) | shares	3,653,897
Weighted-Average Grant Date Fair Value
Unvested at December 31, 2019 (in dollars per share) | $ / shares	$ 50.28
Granted (in dollars per share) | $ / shares	228.36
Vested (in dollars per share) | $ / shares	37.90
Forfeited/Cancelled (in dollars per share) | $ / shares	68.80
Unvested at September 30, 2020 (in dollars per share) | $ / shares	$ 89.29

Stock-Based Compensation - Allo

Stock-Based Compensation - Allocated Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 20,351	$ 13,811
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	2,357	1,620
Marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	1,367	1,224
Product development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	9,784	6,801
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 6,843	$ 4,166