The RealReal, Inc. (REAL) 10-K 1 Mar 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 19, 2021	Jun. 30, 2020
Cover [Abstract]
Entity registrant name	TheRealReal, Inc.
Trading symbol	REAL
Entity central index key	0001573221
Current fiscal year end date	--12-31
Entity filer category	Large Accelerated Filer
Document type	10-K
Document period end date	Dec. 31, 2020
Document fiscal year focus	2020
Document fiscal period focus	FY
Amendment flag	false
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Interactive Data Current	Yes
Entity common stock, shares outstanding		89,835,220
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-38953
Entity Tax Identification Number	45-1234222
Entity Address, Address Line One	55 Francisco Street
Entity Address, Address Line Two	Suite 600
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94133
City Area Code	855
Local Phone Number	435-5893
Title of 12(b) Security	Common stock, $0.00001 par value
Security Exchange Name	NASDAQ
Document Annual Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	DE
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Public Float			$ 828,382,323
ICFR Auditor Attestation Flag	true
Documents Incorporated by Reference	List Part III incorporates information by reference from the definitive proxy statement for the registrant’s 2021 Annual Meeting of Stockholders.

Balance Sheets

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 350,846	$ 154,446
Short-term investments	4,017	208,811
Accounts receivable	7,213	7,779
Inventory, net	42,321	21,916
Prepaid expenses and other current assets	17,072	13,804
Total current assets	421,469	406,756
Property and equipment, net	63,454	55,831
Operating lease right-of-use assets	118,136
Other assets	2,050	2,660
Total assets	605,109	465,247
Current liabilities
Accounts payable	14,346	11,159
Accrued consignor payable	57,053	52,820
Operating lease liabilities, current portion	14,999
Other accrued and current liabilities	61,862	54,567
Total current liabilities	148,260	118,546
Operating lease liabilities, net of current portion	115,084
Convertible senior notes, net	149,188
Other noncurrent liabilities	1,284	9,456
Total liabilities	413,816	128,002
Commitments and contingencies (Note 12)
Stockholders’ equity:
Common stock, $0.00001 par value; 500,000,000 shares authorized as of December 31, 2020 and December 31, 2019; 89,301,664 and 85,872,320 shares issued and outstanding as of December 31, 2020 and December 31, 2019, respectively	1	1
Additional paid-in capital	723,302	693,426
Accumulated other comprehensive income	11	7
Accumulated deficit	(532,021)	(356,189)
Total stockholders’ equity	191,293	337,245
Total liabilities and stockholders’ equity	$ 605,109	$ 465,247

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.00001	$ 0.00001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	89,301,664	85,872,320
Common stock, shares, outstanding	89,301,664	85,872,320

Statements of Operations

Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue:
Total revenue	$ 299,949	$ 316,354	$ 213,732
Cost of revenue:
Total cost of revenue	112,382	114,831	76,814
Gross profit	187,567	201,523	136,918
Operating expenses:
Marketing	54,813	47,734	42,165
Operations and technology	163,808	143,231	104,929
Selling, general and administrative	141,762	110,663	63,728
Total operating expenses	360,383	301,628	210,822
Loss from operations	(172,816)	(100,105)	(73,904)
Interest income	2,518	4,593	1,046
Interest expense	(5,264)	(616)	(1,152)
Other expense, net	(169)	(2,102)	(1,656)
Loss before provision for income taxes	(175,731)	(98,230)	(75,666)
Provision for income taxes	101	199	99
Net loss	(175,832)	(98,429)	(75,765)
Accretion of redeemable convertible preferred stock to redemption value		(3,355)	(8,922)
Net loss attributable to common stockholders	$ (175,832)	$ (101,784)	$ (84,687)
Net loss per share attributable to common stockholders, basic and diluted	$ (2.01)	$ (2.14)	$ (10.12)
Shares used to compute net loss per share attributable to common stockholders, basic and diluted	87,587,409	47,478,544	8,365,344
Consignment and Service Revenue
Revenue:
Total revenue	$ 247,326	$ 265,729	$ 180,607
Cost of revenue:
Total cost of revenue	66,976	73,579	50,855
Direct Revenue
Revenue:
Total revenue	52,623	50,625	33,125
Cost of revenue:
Total cost of revenue	$ 45,406	$ 41,252	$ 25,959

Statements of Comprehensive Los

Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (175,832)	$ (98,429)	$ (75,765)
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on investments	4	32	(19)
Comprehensive loss	$ (175,828)	$ (98,397)	$ (75,784)

Statements of Redeemable Conver

Statements of Redeemable Convertible Preferred Stock, Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Redeemable Convertible Preferred Stock	Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance, shares at Dec. 31, 2017		12,956,724	69,834,789
Beginning balance at Dec. 31, 2017		$ 50,367	$ 122,990
Beginning balance, shares at Dec. 31, 2017				8,287,983
Beginning balance at Dec. 31, 2017	$ (176,986)				$ 4,591	$ (6)	$ (181,571)
Issuance of convertible preferred stock upon conversion of notes, net of issuance costs		$ 5,452	$ 10,202
Issuance of convertible preferred stock upon conversion of notes, net of issuance costs, shares		1,067,550	1,997,709
Loss on extinguishment of convertible notes	(370)				(370)
Issuance of convertible preferred stock, net of issuance costs		$ 86,640	$ 9,627
Issuance of convertible preferred stock, net of issuance costs, shares		17,029,327	1,892,147
Accretion of redeemable convertible preferred stock to redemption value	(8,922)	$ 8,922			(8,593)		(329)
Issuance of common stock upon exercise of options	481				481
Issuance of common stock upon exercise of options, shares				247,797
Issuance of common stock upon exercise of warrants	133				133
Issuance of common stock upon exercise of warrants, shares				57,297
Compensation expense related to stock sales by current and former employees	847				847
Stock-based compensation expense	2,911				2,911
Other comprehensive income (loss)	(19)					(19)
Net loss	$ (75,765)						(75,765)
Ending balance, shares at Dec. 31, 2018	104,778,246	31,053,601	73,724,645
Ending balance at Dec. 31, 2018	$ 294,200	$ 151,381	$ 142,819
Ending balance, shares at Dec. 31, 2018				8,593,077
Ending balance at Dec. 31, 2018	(257,690)					(25)	(257,665)
Issuance of convertible preferred stock, net of issuance costs		$ 43,492	$ 26,283
Issuance of convertible preferred stock, net of issuance costs, shares		6,350,345	3,831,766
Accretion of redeemable convertible preferred stock to redemption value	(3,355)	$ 3,355			(3,260)		(95)
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering	198,228				198,228
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering, shares		(37,403,946)
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering		$ (198,228)
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering, shares				19,585,426
Conversion of convertible preferred stock to common stock in connection with initial public offering	169,102				169,102
Conversion of convertible preferred stock to common stock in connection with initial public offering, shares			(77,556,411)
Conversion of convertible preferred stock to common stock in connection with initial public offering			$ (169,102)
Conversion of convertible preferred stock to common stock in connection with initial public offering, shares				38,778,180
Conversion of convertible preferred stock warrants to common stock warrants in connection with initial public offering	2,710				2,710
Issuance of common stock in connection with initial public offering, net of issuance costs of $5,333	315,518				315,518
Issuance of common stock in connection with initial public offering, net of issuance costs of $5,333, shares				17,250,000
Issuance of common stock upon exercise of options	2,696			$ 1	2,695
Issuance of common stock upon exercise of options, shares				1,551,313
Issuance of common stock upon exercise of warrants	33				33
Issuance of common stock upon exercise of warrants, shares				10,677
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes	(130)				(130)
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes, shares				14,105
Issuance of common stock upon cashless exercise of warrants, shares				89,542
Compensation expense related to stock sales by current and former employees	819				819
Stock-based compensation expense	7,711				7,711
Other comprehensive income (loss)	32					32
Net loss	(98,429)						(98,429)
Ending balance, shares at Dec. 31, 2019				85,872,320
Ending balance at Dec. 31, 2019	337,245			$ 1	693,426	7	(356,189)
Purchase of capped calls	(22,546)				(22,546)
Equity component of convertible senior notes, net of issuance costs	19,020				19,020
Issuance of common stock upon exercise of options	8,859				8,859
Issuance of common stock upon exercise of options, shares				2,604,494
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes	(751)				(751)
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes, shares				733,385
Issuance of common stock for exercises under ESPP	972				972
Issuance of common stock for exercises under ESPP, shares				91,465
Stock-based compensation expense	24,322				24,322
Other comprehensive income (loss)	4					4
Net loss	(175,832)						(175,832)
Ending balance, shares at Dec. 31, 2020				89,301,664
Ending balance at Dec. 31, 2020	$ 191,293			$ 1	$ 723,302	$ 11	$ (532,021)

Statements of Redeemable Conv_2

Statements of Redeemable Convertible Preferred Stock, Convertible Preferred Stock and Stockholders' Equity (Deficit) (Unaudited) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Initial Public Offering
Issuance of stock, net of issuance costs		$ 5,333
Series G Redeemable Convertible Preferred Stock
Convertible preferred stock upon conversion of notes, net of issuance costs			$ 190
Stock issuance costs			3,360
Series G Convertible Preferred Stock
Convertible preferred stock upon conversion of notes, net of issuance costs			355
Stock issuance costs			$ 373
Series H Redeemable Convertible Preferred Stock
Stock issuance costs		166
Series H Convertible Preferred Stock
Stock issuance costs		$ 59
Equity Component of Convertible Senior Notes
Stock issuance costs	$ 767

Statements of Cash Flows

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net loss	$ (175,832)	$ (98,429)	$ (75,765)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation and amortization	18,845	13,408	9,290
Stock-based compensation expense	24,322	7,711	2,911
Reduction of operating lease right-of-use assets	16,062
Change in fair value of convertible note derivative liability			1,248
Bad debt expense	903	1,371	999
Compensation expense related to stock sales by current and former employees		819	847
Change in fair value of convertible preferred stock warrant liability		2,100	450
Accrued interest on convertible notes	216		223
Loss on retirement of property and equipment	280		203
Accretion of unconditional endowment grant liability	51	94	118
Accretion of debt discounts and issuance costs	2,399	11	104
Amortization of premiums (discounts) on short-term investments	(137)	(320)	78
Changes in operating assets and liabilities:
Accounts receivable	(337)	(1,579)	(1,572)
Inventory, net	(20,405)	(11,561)	(3,741)
Prepaid expenses and other current assets	(3,443)	(4,108)	(5,338)
Other assets	548	(1,026)	(318)
Operating lease liability	(12,752)
Accounts payable	2,800	6,010	(2,576)
Accrued consignor payable	4,233	17,561	6,587
Other accrued and current liabilities	7,994	10,686	15,681
Other noncurrent liabilities	(166)	2,762	3,376
Net cash used in operating activities	(134,419)	(54,490)	(47,195)
Cash flow from investing activities:
Purchases of short-term investments	(73,280)	(220,609)	(31,454)
Proceeds from maturities of short-term investments	278,215	39,281	9,624
Proceeds from sale of short-term investments			7,023
Capitalized proprietary software development costs	(8,678)	(9,267)	(5,724)
Purchases of property and equipment	(18,253)	(24,761)	(13,392)
Net cash provided by (used in) investing activities	178,004	(215,356)	(33,923)
Cash flow from financing activities:
Proceeds from issuance of common stock in initial public offering, net of issuance costs		315,541
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs		43,492	86,640
Proceeds from issuance of convertible preferred stock, net of issuance costs		26,283	9,627
Proceeds from issuance of convertible notes, net of issuance costs	166,278		14,273
Purchase of capped calls	(22,546)
Proceeds from exercise of stock options and common stock warrants	8,859	2,729	614
Proceeds from issuance of Employee Stock Purchase Program	972
Payment of deferred offering costs			(24)
Taxes paid related to restricted stock vesting	(748)	(130)
Issuance cost paid related to conversion of convertible notes			(545)
Repayment of debt		(9,250)	(4,500)
Net cash provided by financing activities	152,815	378,665	106,085
Net increase in cash, cash equivalents and restricted cash	196,400	108,819	24,967
Cash, cash equivalents, and restricted cash
Beginning of period	154,446	45,627	20,660
End of period	350,846	154,446	45,627
Supplemental disclosures of cash flow information
Cash paid for interest	11	553	666
Cash paid for income taxes	90	102	49
Supplemental disclosures of non-cash investing and financing activities
Issuance of convertible preferred stock upon extinguishment of convertible notes			10,557
Issuance of redeemable convertible preferred stock upon extinguishment of convertible notes			5,642
Accretion of redeemable convertible preferred stock to redemption value		3,355	8,922
Loss on extinguishment of convertible notes			370
Purchases of property and equipment included in accounts payable and other accrued and current liabilities	(583)	1,841	$ 158
Purchases of capitalized proprietary software development costs included in accounts payable and other accrued and current liabilities	338
Reclassification of deferred offering costs		5,333
Conversion of convertible preferred stock warrants in connection with IPO		2,710
Issuance costs associated with issuance of convertible senior notes included in other accrued and current liabilities	$ 469
Redeemable Convertible Preferred Stock
Supplemental disclosures of non-cash investing and financing activities
Conversion of convertible stock in connection with IPO		198,228
Convertible Preferred Stock
Supplemental disclosures of non-cash investing and financing activities
Conversion of convertible stock in connection with IPO		$ 169,102

Description of Business and Bas

Description of Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Description of Business and Basis of Presentation	Note 1. Description of Business and Basis of Presentation Organization and Description of Business The RealReal, Inc. (the “Company”) is an online marketplace for authenticated, consigned luxury goods across multiple categories, including women’s, men’s, kids’, jewelry and watches, and home and art. The Company was incorporated in the state of Delaware on March 29, 2011 and is headquartered in San Francisco, California. Impact of the Coronavirus (“COVID-19”) Pandemic The COVID-19 pandemic Operations in the Company’s authentication centers were initially limited in accordance with shelter-in-place orders . However, operations capacity was no longer limited by restrictions related to COVID-19 during the second half of the year ended December 31, 2020. The Company believes that its financial resources will allow it to manage the anticipated impact of COVID-19 on the Company’s business operations for the foreseeable future. The Company believes its existing cash and cash equivalents and short-term investments as of December 31, 2020 will be sufficient to meet its working capital and capital expenditures needs for at least the next 12 months. Basis of Presentation The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) and, in the opinion of management, reflect all adjustments necessary to state fairly the Company’s financial position, results of operations, comprehensive loss, redeemable convertible preferred stock, convertible preferred stock, and stockholders’ equity (deficit), and cash flows for the periods presented. Certain corrections to the prior periods have been made to conform to the current period presentation, as described in Note 2. The Company’s functional and reporting currency is the U.S. dollar. Initial Public Offering The Company’s registration statement on Form S-1 (the “IPO Registration Statement”) related to its initial public offering (“IPO”) was declared effective on June 27, 2019, and the Company’s common stock began trading on the Nasdaq Global Select Market on June 28, 2019. On July 2, 2019, the Company completed its IPO, selling 15,000,000 shares of common stock at a price to the public of $20.00 per share, plus an additional 2,250,000 shares of common stock at a price to the public of $20.00 per share pursuant to the exercise of the underwriters’ option to purchase additional shares. The Company received aggregate net proceeds of $315.5 million after deducting underwriting discounts and commissions of $24.1 million and issuance costs of $5.3 million. Immediately p rior to the completion of the IPO, the Company filed its Amended and Restated Certificate of Incorporation, which authorizes a total of 500,000,000 shares of common stock and 50,000,000 shares of undesignated preferred stock. The Company recorded the conversion of 114,960,357 shares of convertible preferred stock and redeemable convertible preferred stock then outstanding into 58,363,606 shares of common stock to additional paid-in capital. All outstanding preferred stock warrants converted into an aggregate of 103,563 common stock warrants Reverse Stock Split On June 13, 2019, the Company effected a reverse split of shares of the Company’s common stock on a 1-for-2 basis (the “Reverse Stock Split”). All issued and outstanding shares of common stock, warrants for common stock, options to purchase common stock and the related per share amounts contained in the financial statements have been retroactively adjusted to reflect this Reverse Stock Split for all periods presented. The par value and authorized shares of common stock were not adjusted as a result of the Reverse Stock Split. Additionally, the authorized, issued and outstanding shares of redeemable convertible preferred stock and convertible preferred stock and their related per share amounts, other than the conversion price per share, were not adjusted as a result of the Reverse Stock Split.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of expenses during the reporting period. Significant items subject to such estimates and assumptions include those related to revenue recognition, including the returns reserve, valuation of inventory, software development costs, stock-based compensation, redemption value of redeemable convertible preferred stock, incremental borrowing rates related to lease liability, fair value of the liability component of convertible senior notes, valuation of deferred taxes, and other contingencies. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could differ from those estimates. Net Loss per Share Attributable to Common Stockholders The Company follows the two-class method when computing net loss per common share when shares are issued that meet the definition of participating securities. The two-class method determines net loss per common share for each class of common stock and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income (loss) available or attributable to common stockholders for the period to be allocated between common stock and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. Before the IPO, the Company’s redeemable convertible preferred stock and convertible preferred stock were considered participating securities. However, the holders of such shares did not have a contractual obligation to participate in the Company’s losses. The Company’s convertible senior notes are participating securities as they give the holders the right to receive dividends if dividend or distribution declared to the common stockholders is equal to or greater than the last reported sale price of the Company’s common stock on the trading day immediately preceding the ex-dividend date for such dividend or distribution as if the instruments had been converted into shares of common stock. No undistributed earnings were allocated to the participating securities as the contingent event is not satisfied as of the reporting date. For periods in which the Company reports net losses, diluted net loss per common share attributable to common stockholders is the same as basic net loss per common share attributable to common stockholders, because potentially dilutive common shares and assumed conversion of the convertible senior notes are not assumed to have been issued within the calculation, if their effect is anti-dilutive. Segments The Company has one operating segment and one reportable segment as its chief operating decision maker, who is its Chief Executive Officer, reviews financial information on a consolidated basis for purposes of allocating resources and evaluating financial performance. All long-lived assets are located in the United States and substantially all revenue is attributed to consignors and buyers based in the United States. Revenue Recognition The Company generates revenue from the sale of pre-owned luxury goods through its online marketplace and retail stores. Consignment and Service Revenue The Company provides a service to sell pre-owned luxury goods on behalf of consignors to buyers through its online marketplace and retail stores. The Company retains a percentage of the proceeds received as payment for its consignment service, which the Company refers to as its take rate. The Company reports consignment revenue on a net basis as an agent and not the gross amount collected from the buyer. Title to the consigned goods remains with the consignor until transferred to the buyer upon purchase of the consigned goods and expiration of the allotted return period. The Company does not take title of consigned goods at any time except in certain cases where returned goods become Company-owned inventory. The Company recognizes consignment revenue upon purchase of the consigned good by the buyer as its performance obligation of providing consignment services to the consignor is satisfied at that point. Consignment revenue is recognized net of estimated returns, cancellations, buyer incentives and adjustments. The Company recognizes a returns reserve based on historical experience, which is recorded in other accrued and current liabilities on the balance sheets (see Note 5). Sales tax assessed by governmental authorities is excluded from revenue. Certain transactions provide consignors with a material right resulting from the tiered consignor commission plan. Under this plan, the amount an individual consignor receives for future sales of consigned goods may be dependent on previous consignment sales for that consignor within his/her consignment period. Accordingly, in certain consignment transactions, a small portion of the Company’s consignment revenue is allocated to such material right using the portfolio method and recorded as deferred revenue, which is recorded in other accrued and current liabilities on the balance sheets. The impact of the deferral has not been material to the financial statements. The Company charges shipping fees to buyers and has elected to treat shipping and handling activities performed after control transfers to the buyer as fulfillment activities. All outbound shipping and handling costs are accounted for as fulfillment costs in cost of consignment and service revenue at the time revenue is recognized. The Company also generates subscription revenue from monthly memberships allowing buyers early access to shop for luxury goods. The buyers receive the early access and other benefits over the term of the subscription period, which represents a single stand-ready performance obligation. Therefore, the subscription fees paid by the buyer are recognized over the monthly subscription period. Subscription revenue was not material in 2020, 2019, and 2018. Direct Revenue The Company generates direct revenue from the sale of Company-owned inventory. The Company recognizes direct revenue on a gross basis upon shipment of the purchased good to the buyer as the Company acts as the principal in the transaction. Direct revenue is recognized net of estimated returns, buyer incentives and adjustments. Sales tax assessed by governmental authorities is excluded from revenue. Cost of direct revenue is also recognized upon shipment to the buyer in an amount equal to that paid to the consignor from the original consignment sale, an amount equal to that paid as a direct purchase from a third party, or the lower of cost of the inventory purchased and its net realizable value. Incentives Incentives, which include platform-wide discounts and buyer incentives, may periodically be offered to buyers. Platform-wide discounts are made available to all buyers on the online marketplace. Buyer incentives apply to specific buyers and consist of coupons or promotions that offer credits in connection with purchases on the Company’s platform, and do not impact the commissions paid to consignors. These are treated as a reduction of consignment and service revenue and direct revenue. Additionally, the Company periodically offers commission exceptions to consignors to optimize its supply. These are treated as reduction of consignment and service revenue, and are reflected in the Company’s take rate. The Company may offer a certain type of buyer incentive in the form of site credits to buyers on current transactions to be applied towards future transactions, which are included in other accrued and current liabilities on the balance sheets. Contract Liabilities The Company’s contractual liabilities consist of deferred revenue for material rights primarily related to the tiered consignor commission plan, which are recognized as revenue using a portfolio approach based on the pattern of exercise, and certain unredeemed site credits, which were immaterial as of December 31, 2020 and December 31, 2019. Contract liabilities are recorded in other accrued and current liabilities on the balance sheets and are generally expected to be recognized within one year. Contract liabilities were immaterial as of December 31, 2020 and December 31, 2019. Cost of Revenue Cost of consignment and service revenue consist of shipping costs, credit card fees, packaging, customer service personnel-related costs, website hosting services, and consignor inventory adjustments relating to lost or damaged products. Cost of direct revenue consists of the cost of goods sold, credit card fees, packaging, customer service personnel-related costs, website hosting services, and inventory adjustments. Marketing Marketing expense is comprised of the cost of acquiring new consignors and buyers for our online platform and physical stores, including the cost of television, digital and direct mail advertising. Marketing expense also includes personnel-related costs, including stock-based compensation, of employees engaged in these activities. Advertising costs are expensed as incurred and were $45.8 million, $40.5 million, and $36.6 million in 2020, 2019, and 2018, respectively. Operations and Technology Operations and technology expense is comprised of costs associated with the authentication, merchandising and fulfillment of goods sold through our online marketplace and retail stores, as well as general information technology expense. The principal component of operations and technology expense is personnel-related costs, including stock-based Selling, General and Administrative Selling, general and administrative expense is principally comprised of the personnel-related costs for employees involved in sales, finance and administration, and includes stock-based compensation expense. Selling, general and administrative expense also includes allocated facility and overhead costs and professional services, including accounting and legal advisors. Stock-based Compensation Stock-based compensation expense related to employees and nonemployees is measured based on the grant-date fair value of the awards. Compensation expense is recognized in the statements of operations over the period during which the employee is required to perform services in exchange for the award (the vesting period of the applicable award) using the straight-line method. The Company estimates the fair value of stock options granted using the Black-Scholes option pricing model and accounts for forfeitures as they occur. The fair value of restricted stock units (“RSUs”) is estimated based on the fair market value of the Company’s common stock on the date of grant, which is determined based on the closing price of the Company’s common stock. The fair value of each purchase under the employee stock purchase plan (ESPP) is estimated at the beginning of the offering period using the Black-Scholes option pricing model. Prior to the IPO, certain employees have sold their shares of the Company’s common stock to the Company’s existing investors. In such secondary sale transactions, the Company recorded the difference in purchase price and the fair value of such shares as compensation expense within selling, general and administrative in the statements of operations and a corresponding credit to additional paid-in capital. Cash, Cash Equivalents and Restricted Cash The Company considers all highly liquid investments purchased with original maturities of three months or less from the purchase date to be cash equivalents. Cash equivalents primarily consist of investments in short-term money market funds and amounts invested in U.S. treasury securities. Restricted cash consists of cash deposited with a financial institution as collateral for the Company’s letters of credit for its facility leases and the Company’s credit cards. As of December 31, 2020 and December 31, 2019, the Company had no restricted cash. The following table provides a reconciliation of cash, cash equivalents and restricted cash that sum to the total of the same amounts shown in the statements of cash flows (in thousands): December 31, 2020 December 31, 2019 December 31, 2018 Cash and cash equivalents $ 350,846 $ 154,446 $ 34,393 Restricted cash — — 11,234 Total cash, cash equivalents and restricted cash $ 350,846 $ 154,446 $ 45,627 Short-term Investments The Company has classified and accounted for its short-term investments as available-for-sale which are carried at fair value on its balance sheets. Available-for-sale securities with remaining maturities of 12 months or less are classified as short term and available-for-sale securities with remaining maturities greater than 12 months are classified as long term. Available-for-sale investments are reported at fair value based on quoted market prices and other observable market data. The Company records any unrealized gains and losses within accumulated other comprehensive income (loss) as a component of stockholders’ equity (deficit), of which there were none as of December 31, 2020 and 2019. The Company adopted Accounting Standards Update (ASU) 2016-13 described below under "Recent Adopted Accounting Pronouncements." In accordance with the adopted guidance, the Company replaced the incurred loss approach with an expected loss model and the Company records allowances for available-for-sale debt securities rather than to reduce the carrying amount for other-than-temporary impairment as was followed under the other-than-temporary impairment model prior to January 1, 2020. Realized gains and losses and other-than-temporary impairments on investments are included in Other income and expense, net. As of December 31, 2020, the Company had not recorded any impairments due to credit loss. Accounts Receivable Accounts receivables are recorded at the amounts billed to buyers and do not bear interest. Accounts receivables result from credit card transactions, the majority of which are settled within two business days. Inventory, Net Inventory consists of finished goods arising from goods returned after the title has transferred from the buyer to the Company as well as finished goods from direct purchases from vendors and consignors. The cost of inventory is an amount equal to that paid to the consignor or vendors. Inventory is valued at the lower of cost and net realizable value using the specific identification method and the Company records provisions, as appropriate, to write down obsolete and excess inventory to estimated net realizable value. After the inventory value is reduced, adjustments are not made to increase it from the estimated net realizable value. Our provisions to write down obsolete and excess inventory to net realizable value have not been material for 2020 and 2019. Return reserves, which reduce revenue and cost of sales, are estimated using historical experience. Liabilities for return allowances are included in other accrued and current liabilities on the balance sheets and were $18.3 million and $17.0 million as of December 31, 2020 and 2019. Included in inventory on the Company’s balance sheets are assets totaling $7.4 million and $7.1 million as of December 31, 2020 and 2019, for the rights to recover products from customers associated with its liabilities for return reserves. Property and Equipment, Net Property and equipment, net is recorded at cost less accumulated depreciation and amortization. Depreciation and amortization are recorded on a straight-line basis over the estimated useful lives of the respective assets. Repair and maintenance costs are expensed as incurred. The estimated useful lives of our assets are as follows: Proprietary software 3 years Furniture and equipment 3-5 years Vehicles 5 years Leasehold improvements Shorter of lease term or estimated useful life Software Development Costs Proprietary software includes the costs of developing the Company’s internal proprietary business platform and automation projects. The Company capitalizes qualifying proprietary software development costs that are incurred during the application development stage. Capitalization of costs begins when two criteria are met: (1) the preliminary project stage is completed and (2) it is probable that the software will be completed and used for its intended function. Such costs are capitalized in the period incurred. Capitalization ceases and amortization begins when the software is substantially complete and ready for its intended use, including the completion of all significant testing. Costs related to preliminary project activities and post-implementation operating activities are expensed as incurred. Impairment of Long-lived Assets The carrying amounts of long-lived assets, including property and equipment, net and capitalized proprietary software, are periodically reviewed for impairment whenever events or changes in circumstances indicate that the carrying value of these assets may not be recoverable or that the useful life is shorter than originally estimated. Recoverability of assets to be held and used is measured by comparing the carrying amount of assets to future undiscounted net cash flows the assets are expected to generate over their remaining life. If the assets are considered to be impaired, the amount of any impairment is measured as the difference between the carrying value and the fair value of the impaired assets. If the useful life is shorter than originally estimated, the Company amortizes the remaining carrying value over the revised shorter useful life. Deferred Offering Costs Deferred offering costs, which consist of direct incremental legal, consulting, banking and accounting fees relating to the anticipated equity offering, are capitalized and offset against proceeds upon the consummation of the offering. In the event an anticipated offering is abandoned, deferred offering costs will be expensed. In 2020, offering costs of $6.7 million related to the issuance of convertible notes was allocated to the liability and equity components based on the allocation of the proceeds. Of the total offering costs, $0.8 million was recorded as a reduction to additional paid-in capital and $5.9 million was recorded as a reduction in the carrying value of the debt on the balance sheet. In 2019, offering costs of $0.3 million were expensed. As of December 31, 2019, $5.3 million deferred offering costs were offset against the IPO proceeds within stockholders’ equity (deficit) on the balance sheets. Accretion of Redeemable Convertible Preferred Stock The carrying value of the redeemable convertible preferred stock that is probable of redemption is accreted to redemption value from the date of issuance to the earliest redemption date using the effective interest method until redemption is no longer probable. Increases to the carrying value of redeemable convertible preferred stock recognized in each period are charged to additional paid-in capital, or in the absence of additional paid-in capital, charged to accumulated deficit. Convertible Preferred Stock Warrant Liability The Company issued convertible preferred stock warrants in conjunction with the issuance of debt. Such warrants were recorded as other noncurrent liabilities on the balance sheets at their estimated fair value because the shares underlying the warrants may obligate the Company to transfer assets to the holders at a future date under certain circumstances such as a deemed liquidation event. The warrants are subject to re-measurement at each balance sheet date and the change in fair value, if any, is included in other expense, net. The Company continued to remeasure these warrants until the earlier of the expiration, exercise or conversion of the convertible preferred stock warrants into common warrants, which occurred upon the completion of the IPO on July 2, 2019. In connection with the completion of the IPO, the convertible preferred stock warrants automatically converted into common stock warrants. Upon conversion of the convertible preferred stock warrants, the related convertible preferred stock warrant liability was reclassified to additional paid-in capital. Leases Prior to the adoption of ASC 842 on January 1, 2020 Leases are reviewed for classification as operating or capital leases. For operating leases, the Company recognizes rent on a straight-line basis over the term of the lease. The Company records the difference between cash payments and rent expense recognized as a deferred rent liability included in other accrued and current liabilities and other noncurrent liabilities on the balance sheets. Incentives granted under the Company’s facility leases, including allowances to fund leasehold improvements, are deferred and are recognized as adjustments to rental expense on a straight-line basis over the term of the lease. Subsequent to the adoption of ASC 842 on January 1, 2020 Contracts that have been determined to convey the right to use an identified asset are evaluated for classification as an operating or finance lease. For the Company’s operating leases, the Company records a lease liability based on the present value of the lease payments at lease inception, using the applicable incremental borrowing rate. The Company estimates the incremental borrowing rate by developing its own synthetic credit rating, corresponding yield curve, and the terms of each lease at the lease commencement date. The corresponding right-of-use asset is recorded based on the corresponding lease liability at lease inception, adjusted for payments made to the lessor at or before the commencement date, initial direct costs incurred and any tenant incentives allowed for under the lease. The Company does not include optional renewal terms or early termination provisions unless the Company is reasonably certain such options would be exercised at the inception of the lease. Operating lease right-of-use assets, current portion of operating lease liabilities, and operating lease liabilities, net of current portion are included on the Company’s balance sheet. The Company has elected the practical expedients that allows for the combination of lease components and non-lease components and to record short-term leases as lease expense on a straight-line basis on the statements of operations. Variable lease payments are recorded as expense as they are incurred. The Company has finance leases for vehicles and equipment, and the amounts of finance lease right-of-use assets and finance lease liabilities have been immaterial to date. Convertible Senior Notes Convertible debt instruments that may be settled in cash or other assets, or partially in cash, upon conversion, are separately accounted for as long-term debt and equity components (or conversion feature). The accounting applies to the Company’s convertible senior notes (the “Notes”) issued in June 2020. The debt component represents the Company’s contractual obligation to pay principal and interest and the equity component represents the Company’s option to convert the debt security into equity of the Company or the equivalent amount of cash. Upon issuance, the Company allocated the debt component on the basis of the estimated fair value of an identical debt instrument that it would issue excluding the conversion option and the remaining proceeds are allocated to the equity component. The bifurcation of the debt and equity components resulted in a debt discount for the aforementioned notes. The Company uses the interest method to amortize the debt discount to interest expense over the amortization period which is the expected life of the debt. Capped Call Transactions In June 2020, in connection with the issuance of its convertible senior notes, the Company entered into Capped Call Transactions (see Note 7). The Capped Call Transactions are expected generally to reduce the potential dilution to the holders of the Company’s common stock upon any conversion of the Notes and/or offset any cash payments the Company is required to make in excess of the principal amount of converted Notes, with such reduction and/or offset subject to a cap based on the cap price. The capped calls are classified in stockholders’ equity as a reduction to additional paid-in capital and are not subsequently remeasured as long as the conditions for equity classification continue to be met. Debt Issuance Costs Debt issuance costs are amortized to interest expense over the estimated life of the related debt based on the effective interest method. The Company presents debt issuance costs on the balance sheet as a direct deduction from the associated debt. A portion of debt issuance costs incurred in connection with the Notes issued in June 2020 was related to the equity component and was recorded as a reduction to additional paid in capital and is not amortized to interest expense over the estimated life of the related debt. Income Taxes Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in loss in the period of enactment. The Company recognizes the effect of income tax positions only if those positions are more likely than not of being sustained. Recognized income tax positions are measured at the largest amount that is greater than 50% likely of being realized. Changes in recognition or measurement are reflected in the period in which the change in judgment occurs. Concentrations of Credit Risks Financial instruments that potentially subject the Company to concentrations of credit risk consist of cash and cash equivalents, restricted cash, accounts receivable, and investments. At times, such amount may exceed federally-insured limits. The Company reduces credit risk by placing its cash and cash equivalents, restricted cash, and investments with major financial institutions within the United States. As of December 31, 2020 and December 31, 2019, there were no customers that represented 10% or more of the Company’s accounts receivable balance and there were no customers that individually exceeded 10% of the Company’s total revenue for each of the years ended December 31, 2020, 2019, and 2018. Immaterial Correction of an Error in Prior Periods During the quarter ended December 31, 2020, the Company identified an overstatement of consignment and services revenue and inventory, net as a result of an error in accounting for inventory associated with commissions paid outside of our normal payment cycle to consignors for returned merchandise. In accordance with FASB Accounting Standards Codification 250, Accounting Changes and Error Corrections The following table presents the effects of the immaterial error correction on the balance sheet and related statements of redeemable convertible preferred stock, convertible preferred stock, and stockholders’ equity (deficit) for the period indicated (in thousands): As of December 31, 2019 As previously reported Adjustments As Adjusted Current Assets: Inventory, net $ 23,599 $ (1,683 ) $ 21,916 Total current assets 408,439 (1,683 ) 406,756 Total assets $ 466,930 $ (1,683 ) $ 465,247 Stockholders' equity (deficit): Accumulated deficit (354,506 ) (1,683 ) (356,189 ) Total stockholders' equity (deficit) 338,928 (1,683 ) 337,245 Total liabilities and stockholders’ equity (deficit) $ 466,930 $ (1,683 ) 465,247 The following table presents the effects of the immaterial error correction on the statements of operations and net loss per share attributable to common stockholders, basic and diluted for the period indicated (in thousands): Year Ended December 31, 2019 As previously reported Adjustments As Adjusted Revenue: Consignment and service revenue $ 267,412 $ (1,683 ) $ 265,729 Direct revenue 50,625 — 50,625 Total revenue 318,037 (1,683 ) 316,354 Gross profit 203,206 (1,683 ) 201,523 Loss from operations (98,422 ) (1,683 ) (100,105 ) Loss before provision for income taxes (96,547 ) (1,683 ) (98,230 ) Net loss $ (96,746 ) $ (1,683 ) $ (98,429 ) Net loss attributable to common stockholders $ (100,101 ) $ (1,683 ) $ (101,784 ) Net loss per share attributable to common stockholders, basic and diluted $ (2.11 ) (0.03 ) $ (2.14 ) Shares used to compute net loss per share attributable to common stockholders, basic and diluted 47,478,544 — 47,478,544 The following table presents the effects of the immaterial error correction on the statements of comprehensive loss (in thousands): Year Ended December 31, 2019 As previously reported Adjustments As Adjusted Net loss $ (96,746 ) $ (1,683 ) $ (98,429 ) Other comprehensive income (loss), net of tax Unrealized gain (loss) on investments 32 — 32 Comprehensive loss $ (96,714 ) $ (1,683 ) (98,397 ) The following table presents the effects of the immaterial error correction on the statements of cash flows (in thousands): Year ended December 31, 2019 As previously reported Adjustments As Adjusted Cash flows from operating activities: Net loss $ (96,746 ) $ (1,683 ) $ (98,429 ) Changes in operating activities and liabilities: Inventory, net (13,244 ) 1,683 (11,561 ) Net cash used in operating activities $ (54,490 ) $ — (54,490 ) Recently Adopted Accounting Pronouncements The Company was an emerging growth company “EGC”, as defined in the Jumpstart Our Business Startups Act of 2012 (JOBS Act). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The Company had elected to use this extended transition period to enable it to comply with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date it (1) was no longer an emerging growth company or (2) affirmatively and irrevocably opt out of the extended transition period provided in the JOBS Act. The Company chose to adopt new or revised accounting standards earlier than such time those standards apply to private companies and retain its election for the extended transition period, if early adoption is permitted for all entities. As a result, our financial statements may not be comparable to companies that comply with new or revised accounting pronouncements as of public company effective dates. Because the market value of the Company’s common stock held by non-affiliates exceeded $700 million as of June 30, 2020, the Company ceased to be an emerging growth company and was deemed a “large accelerated filer” under the Exchange Act as of December 31, 2020. As a result, the Company adopted all applicable standards retrospectively as of January 1, 2020 in this Annual Report on Form 10-K. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) The Company adopted Topic 842 on January 1, 2020 using the modified retrospective approach and applied it to all existing leases as of the adoption date, which allows for a cumulative-effect adjustment to retained earnings on the adoption date. The Company will continue to present prior period amounts under ASC 840. In addition, the Company elected the package of practical expedients permitted under the transition guidance within the new standard which does not require the Company to reassess whether contracts that expired prior to the adoption date contained an embedded lease, reassess historical lease classification, or evaluate direct costs for leases that were in effect at the adoption date. As a result of implementing this guidance, the Company recognized $110.3 million in right of use assets as of January 1, 2020. The Company also recorded $12.8 million in current operating lease liabilities and $106.2 million in operating lease liabilities, net of current portion in its balance sheet as of January 1, 2020. In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses: Measurement of Credit Losses

Cash, Cash Equivalents and Shor

Cash, Cash Equivalents and Short-term Investments	12 Months Ended
	Dec. 31, 2020
Cash And Cash Equivalents [Abstract]
Cash, Cash Equivalents, and Short-term Investments	Note 3. Cash, Cash Equivalents and Short-term Investments The following tables summarize the estimated value of the Company’s cash, cash equivalents and short-term investments (in thousands): December 31, 2020 Amortized Cost Unrealized Gain Unrealized Loss Fair Value Cash and cash equivalents: Cash $ 150,520 $ — $ — $ 150,520 Money market fund 200,326 — — 200,326 Total cash and cash equivalents $ 350,846 $ — $ — $ 350,846 Short-term investments: Corporate bonds $ 4,006 $ 11 $ — $ 4,017 Total short-term investments $ 4,006 $ 11 $ — $ 4,017 December 31, 2019 Amortized Cost Unrealized Gain Unrealized Loss Fair Value Cash and cash equivalents: Cash $ 111,319 $ — $ — $ 111,319 U.S. Treasury securities 29,981 — — 29,981 Money market fund 5,399 — — 5,399 Corporate bonds 3,749 — — 3,749 Agency bonds 2,000 — — 2,000 Commercial paper 1,998 — — 1,998 Total cash and cash equivalents $ 154,446 $ — $ — $ 154,446 Short-term investments: U.S. Treasury securities $ 151,857 $ 13 $ — $ 151,870 Corporate bonds 38,149 — (5 ) 38,144 Agency bonds 11,028 — (2 ) 11,026 Commercial paper 7,770 1 — 7,771 Total short-term investments $ 208,804 $ 14 $ (7 ) $ 208,811 As of December 31, 2020 and December 31, 2019, the contractual maturity for the short-term investments is less than one year. For the years ended December 31, 2020, 2019, and 2018 the Company recognized no material realized gains or losses on short-term investments.

Fair Value Measurement

Fair Value Measurement	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurement	Note 4. Fair Value Measurement Assets and liabilities recorded at fair value on a recurring basis on the balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1—Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date. Level 2—Inputs (other than quoted prices included in Level 1) are either directly or indirectly observable for the asset or liability. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. There were no transfers between Level 1, Level 2 or Level 3 of the fair value hierarchy during the periods presented. The following tables provide the financial instruments measured at fair value (in thousands): December 31, 2020 Level 1 Level 2 Level 3 Total Assets (1) Short-term investments: Corporate bonds $ — $ 4,017 $ — $ 4,017 Total short-term investments $ — $ 4,017 $ — $ 4,017 December 31, 2019 Level 1 Level 2 Level 3 Total Assets Cash equivalents: (1) U.S. Treasury securities $ 29,981 $ — $ — $ 29,981 Corporate bonds — 3,749 — 3,749 Agency bonds — 2,000 — 2,000 Commercial paper — 1,998 — 1,998 Total cash equivalents $ 29,981 $ 7,747 $ — $ 37,728 Short-term investments: U.S. Treasury securities $ 151,870 $ — $ — $ 151,870 Corporate bonds — 38,144 — 38,144 Agency bonds — 11,026 — 11,026 Commercial paper — 7,771 — 7,771 Total short-term investments $ 151,870 $ 56,941 $ — $ 208,811 (1) Money market funds are measured at net asset value per share and are excluded from cash equivalents in the fair value hierarchy table. The amounts of the money market funds (in thousands) were $200,326 and $5,399 at 12/31/20 and 12/31/19, respectively. On June 15, 2020, the Company issued 3.00% convertible senior notes due 2025 with embedded conversion features. The Company estimated the fair value of the Notes using a discounted cash flow approach to derive the value of a debt instrument using the expected cash flows and the estimated yield related to the convertible senior notes. The significant assumptions used in estimating the expected cash flows were the estimated market yield based on an implied yield and credit quality analysis of a term loan with similar attributes. The Company recorded approximately $152.7 million as the fair value of the liability on June 15, 2020, with a corresponding amount recorded as a discount on the initial issuance of the Notes of approximately $19.8 million. The debt discount was recorded to equity and is being amortized to the debt liability over the life of the Notes using the effective interest method. As of December 31, 2020, the fair value of the Notes, which differs from its carrying value is determined by prices for the Notes observed in market trading. The market for trading of the Notes is not considered to be an active market and therefore the estimate of fair value is based on Level 2 inputs, such as interest rates. As of December 31, 2020, the estimated fair value of the Notes, which has an aggregate face value of $172.5 million, was $184.4 million based on the market price on the last trading day for the period. The fair value of the convertible preferred stock warrant liability on the date of issuance and each re-measurement date was estimated using the Black‑Scholes option pricing model. Inputs used to determine the estimated fair value as of each valuation date included expected term of the warrants, the risk-free interest rate, volatility, and the fair value of underlying shares. Due to the nature of these valuation models, the valuation of the warrants is considered a Level 3 measurement. The following table presents a rollforward of the fair value of the Level 3 liability recorded at fair value (in thousands): Convertible Preferred Stock Warrant Liability Balance as of December 31, 2018 610 Changes in estimated fair value 2,100 Reclass to additional paid-in capital upon conversion to common stock warrants (2,710 ) Balance as of December 31, 2019 $ —

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	Note 5. Balance Sheet Components Property and Equipment, Net Property and equipment, net is recorded at cost less accumulated depreciation and amortization. Depreciation and amortization are recorded on a straight-line basis over the estimated useful lives of the respective assets. Property and equipment, net consists of the following (in thousands): December 31, 2020 December 31, 2019 Proprietary software $ 24,218 $ 23,318 Furniture and equipment 27,687 21,083 Automobiles 668 718 Leasehold improvements 52,828 43,505 105,401 88,624 Less: accumulated depreciation and amortization (41,947 ) (32,793 ) Property and equipment, net $ 63,454 $ 55,831 Depreciation and amortization expense on property and equipment was $18.8 million, $13.4 million, and $9.3 million for the years ended December 31, 2020, 2019 and 2018, respectively. During the year ended December 31, 2020, fully depreciated proprietary software in the amount of $7.9 million was taken out of service. Other Accrued and Current Liabilities Other accrued and current liabilities consist of the following (in thousands): December 31, 2020 December 31, 2019 Returns reserve $ 18,327 $ 17,005 Accrued compensation 13,406 11,626 Accrued marketing and outside services 10,790 6,830 Site credit liability 5,475 5,080 Accrued sales tax and other taxes 6,870 6,132 Deferred revenue 1,617 4,767 Other 5,377 3,127 Other accrued and current liabilities $ 61,862 $ 54,567

Debt and Convertible Preferred

Debt and Convertible Preferred Stock Warrants	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Debt and Convertible Preferred Stock Warrants	Note 6. Debt and Convertible Preferred Stock Warrants Term Loans In 2013, the Company entered into an agreement to obtain a term loan facility (“Term Loan Facility”) in the amount of $5.0 million for general corporate purposes and working capital expenditures. In 2014, 2015 and 2016, the Company amended its Term Loan Facility to increase the amount borrowed under the facility by $11.6 million. The Term Loan Facility is secured by liens on substantially all of the Company’s present and future assets. The Term Loan Facility includes affirmative, negative and financial covenants that restrict the Company’s ability to, among other things, incur additional indebtedness, make investments, sell or otherwise dispose of assets, pay dividends or repurchase stock. The Term Loan Facility’s financial covenants required the Company to achieve at least 80% of its forecasted gross revenue and a liquidity ratio on a monthly basis. In 2017, the Company executed the eighth amendment (“Eight Amendment”) to the Term Loan Facility. The Eighth Amendment refinanced the $15.0 million repayment schedule to be two term loans, which included a $7.5 million interest only term loan with a maturity date of January 31, 2019 (“Term Loan I”), and the remaining $7.5 million under the existing Term Loan Facility with a maturity date of January 1, 2020 (“Term Loan II”) (together the “Term Loans”). In 2018, the Company entered into the ninth, tenth, eleventh, and twelfth amendment (“Ninth Amendment,” “Tenth Amendment,” “Eleventh Amendment” and “Twelfth Amendment”) to the existing Term Loans. The Ninth Amendment removed the liquidity ratio covenant, amended Term Loan I to be due in 30 equal monthly installments, plus all accrued interest, beginning July 31, 2018, increased the variable annual interest rate from 0.10% above the prime rate to 0.35% above the prime rate and extended the maturity date of Term Loan I to January 31, 2021. The Eighth Amendment and Ninth Amendment required the Company to pay a combined success fee of $0.3 million upon (1) any sale or licensing of all or substantially all of the Company’s assets, (2) any change in control of the Company, or (3) an initial public offering of the Company’s equity securities. The Ninth Amendment also required the Company to pay an additional success fee of $0.1 million upon the sale or issuance of the Company’s equity securities or subordinated debt securities for net cash proceeds of at least $50.0 million on or prior to June 30, 2018. The Company paid the $0.1 million success fee upon the Series G convertible preferred stock financing in June 2018 and the $0.3 million success fee related to its IPO in July 2019. The Tenth and Twelfth Amendments adjusted and waived certain covenant violations which were subsequently amended and met. The Eleventh Amendment provided an additional letter of credit of $1.5 million for corporate credit cards with a maturity date of August 1, 2019. On July 26, 2019 the Company fully repaid the principal of its Term Loans in the amount of $6.5 million. With the repayment of the term loans, the Company was no longer subject to debt covenants as of December 31, 2020. During the years ended December 31, 2020, 2019 and 2018, the Company recorded interest expense related to the Term Loans of zero, $0.3 million, and $0.7 million, respectively. Warrants Issued with Term Loan Facility During the period from 2013 to 2016, in connection with the Term Loan Facility, the Company issued convertible preferred stock warrants, which included warrants to purchase 131,652 shares of its Series B convertible preferred stock with an exercise price of $1.03 per share, 6,868 shares of its Series C convertible preferred stock with an exercise price of $2.18 per share, 43,010 shares of its Series D convertible preferred stock with an exercise price of $2.79 per share and 25,597 shares of its Series E convertible preferred stock with an exercise price of $2.93 per share (together the “Convertible Preferred Stock Warrants”). The Convertible Preferred Stock Warrants were exercisable from the date of issuance and have a 10-year term. The initial estimated fair value of the Convertible Preferred Stock Warrants was recorded as convertible preferred stock warrant liability with an offset to the debt discount associated with the Term Loan Facility. The debt discount is amortized to interest expense over the repayment period of the loan using the effective-interest method. All convertible Preferred Stock Warrants were converted to common stock warrants and exercised through net share settlement in July 2019. No warrants were outstanding as of December 31, 2020 and 2019.

Convertible Notes

Convertible Notes	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Convertible Notes	Note 7. Convertible Notes 2025 Convertible Senior Notes In June 2020, the Company issued an aggregate principal of $172.5 million of its 3.00% Convertible Senior Notes due 2025 (the “Notes”), pursuant to an indenture (the “Indenture”) between the Company and U.S. Bank National Association, as trustee, in a private offering (the “Note Offering”) to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, as amended (the “Securities Act”). The Notes issued in the Note Offering include $22.5 million in aggregate principal amount of the Notes sold to the initial purchasers resulting from the exercise in full of their option to purchase additional Notes. The Notes will mature on June 15, 2025, unless earlier redeemed or repurchased by the Company or converted. The Company received net proceeds from the Notes offering of approximately $165.8 million, after deducting the initial purchasers’ discount and commission and offering expenses. The Company used approximately $22.5 million of the net proceeds from the Notes offering to fund the net cost of entering into the capped call transactions described below. The Company intends to use the remainder of the net proceeds for general corporate purposes. The Notes accrue interest at a rate of 3.00% per annum, payable semi-annually in arrears on June 15 and December 15 of each year, beginning on December 15, 2020. The initial conversion rate applicable to the Notes is 56.2635 shares of common stock per $1,000 principal amount of Notes (which is equivalent to an initial conversion price of approximately $17.77 per share of the Company’s common stock). The conversion rate is subject to adjustment upon the occurrence of certain specified events but will not be adjusted for accrued and unpaid interest. In addition, upon the occurrence of a corporate event, the Company will, in certain circumstances, increase the conversion rate by a number of additional shares for a holder that elects to convert its Notes in connection with such corporate event. The Notes will be redeemable, in whole or in part, at the Company’s option at any time, and from time to time, on or after June 20, 2023 if the last reported sale price per share of the Company’s common stock exceeds 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive), including the trading day immediately preceding the date on which the Company provides notice of redemption, during any 30 consecutive trading day period ending on, and including, the trading day immediately before the date the Company sends the related redemption notice. In addition, calling any Note for redemption will constitute a make-whole fundamental change with respect to that Note, in which case the conversion rate applicable to the conversion of that Note will be increased in certain circumstances if it is converted after it is called for redemption. Prior to March 15, 2025, the Notes will be convertible only under the following circumstances: • During any calendar quarter (and only during such calendar quarter) beginning after September 30, 2020, if, the last reported sale price per share of the Company’s common stock exceeds 130% of the applicable conversion price on each applicable trading day for at least 20 trading days (whether or not consecutive) in the period of the 30 consecutive trading day period ending on, and including, the last trading day of the immediately preceding calendar quarter. • During the five business day period after any five consecutive trading day period in which, for each day of that period, the trading price per $1,000 principal amount of Notes for such trading day was less than 98% of the product of the last reported sale price of the Company’s common stock and the applicable conversion rate on such trading day; • Upon the occurrence of specified corporate transactions; or • If the Company calls any notes for redemption. On and after March 15, 2025, until the close of business on the scheduled trading day immediately preceding the maturity date, holders may convert all or a portion of their Notes, in multiples of $1,000 principal amount, at any time, regardless of the foregoing circumstances. Upon conversion, the Notes will be settled, at the Company’s election, in cash, shares of the Company’s common stock, or a combination of cash and shares of the Company’s common stock. It is the Company’s current intent to settle conversions of the Notes through combination settlement, which involves repayment of the principal portion in cash and any excess of the conversion value over the principal amount in shares of its common stock. The Notes are unsecured and unsubordinated obligations of the Company and will rank senior in right of payment to any of future indebtedness of the Company that is expressly subordinated in right of payment to the Notes; rank equal in right of payment to any existing and future unsecured indebtedness of the Company that is not so subordinated; be effectively subordinated in right of payment to any secured indebtedness of the Company to the extent of the value of the assets securing such indebtedness; and be structurally subordinated to all existing and future indebtedness and other liabilities and obligations incurred by future subsidiaries of the Company. If bankruptcy, insolvency, or reorganization occurs with respect to the Company (and not solely with respect to a significant subsidiary of the Company), then the principal amount of, and all accrued and unpaid interest on, all of the Notes then outstanding will immediately become due and payable without any further action or notice by any person. If an event of default (other than bankruptcy, insolvency, or reorganization with respect to the Company and not solely with respect to a significant subsidiary of ours) occurs and is continuing, then, with the exception of certain reporting events of default, the trustee, by notice to the Company, or noteholders of at least 25% of the aggregate principal amount of notes then outstanding, by notice to us and the trustee, may declare the principal amount of, and all accrued and unpaid interest on, all of the Notes then outstanding to become due and payable immediately. In accounting for the issuance of the Notes, the Company separately accounted for the liability and equity components of the Notes by allocating the proceeds between the liability component and the embedded conversion options, or equity component, due to Company’s ability to settle the Notes in cash, its common stock, or a combination of cash and common stock at Company’s option. The allocation was done by first estimating the fair value of the liability component and the residual value was assigned to the equity component. The value of the liability component was calculated by measuring the fair value of a similar liability that does not have an associated convertible feature. The allocation was performed in a manner that reflected the Company’s non-convertible debt borrowing rate for similar debt. The interest rate of 5.67% was used to compute the initial fair value of the liability component of $152.7 million. The equity component is not remeasured as long as it continues to meet the conditions for equity classification. The net carrying amount of the liability component of the Notes was as follows: December 31, 2020 Principal $ 172,500 Unamortized debt discount (17,945 ) Unamortized debt issuance costs (5,367 ) Net carrying amount $ 149,188 The net carrying amount of the equity component of the Notes was as follows: December 31, 2020 Proceeds allocated to the conversion options (debt discount) $ 19,787 Issuance costs (767 ) Net carrying amount $ 19,020 In connection with the issuance of the Notes, the Company incurred approximately $6.7 million of debt issuance costs, which primarily consisted of initial purchasers’ discounts and legal and other professional fees. The Company allocated these costs to the liability and equity components based on the allocation of the proceeds. The portion of these costs allocated to the equity component totaling approximately $0.8 million was recorded as a reduction to additional paid-in capital. The portion of these costs allocated to the liability component totaling approximately $5.9 million was recorded as a reduction in the carrying value of the debt on the balance sheets and is amortized to interest expense using the effective interest method over the expected life of the Notes or approximately its five-year term. The effective interest rate on the liability component of the Notes for the period from the date of issuance through December 31, 2020 was 6.4%. The following table sets forth the amounts recorded in interest expense related to the Notes from the date of issuance through December 31, 2020: Amount Contractual interest expense $ 2,803 Amortization of debt discount 1,843 Amortization of debt issuance costs 556 Total interest and amortization expense $ 5,202 Future minimum payments under the Notes as of December 31, 2020, are as follows: Fiscal Year Amount 2021 $ 5,175 2022 5,175 2023 5,175 2024 5,175 2025 175,088 Total future payments 195,788 Less amounts representing interest (23,288 ) Total principal amount $ 172,500 Capped Call Transactions with Respect to the Notes In June 2020, in connection with the issuance of the Notes, including the initial purchasers’ exercise of the option to purchase additional Notes, the Company entered into capped call transactions with respect to its common stock (the “Purchased Calls”) with certain financial institutions (collectively, the “Counterparties”). The Company paid an aggregate amount of approximately $22.5 million to the Counterparties for the Purchased Calls. The Purchased Calls cover, subject to anti-dilution adjustments that are intended to be substantially identical to those in the Notes, approximately 9,705,454 shares of the Company’s common stock at a strike price that corresponds to the initial conversion price of the Notes, also subject to adjustment, and are exercisable upon conversion of the Notes. The Purchased Call are subject to adjustment upon the occurrence of specified extraordinary events affecting the Company, including merger events, tender offer and announcement events. In addition, the Purchase Calls are subject to certain specified additional disruption events that may give rise to a termination of the Purchased Calls, including nationalization, insolvency or delisting, changes in law, failures to deliver, insolvency filings and hedging disruptions. The Purchased Calls settle in components commencing on April 16, 2025 with the last component scheduled to expire on June 12, 2025. The cap price of the capped call transactions is initially $27.88 per share, which represents a premium of 100.0% over the closing price of the Company’s common stock of $13.94 per share on June 10, 2020, and is subject to certain adjustments under the terms of the capped call transactions. The Company expects to receive from the Counterparties a number of shares of the Company’s common stock or, at the Company’s election (subject to certain conditions), cash, with an aggregate market value (or, in the case of cash settlement, in an amount) approximately equal to the product of such excess times the number of shares of the Company’s common stock relating to the Purchased Calls being exercised. These Capped Call instruments meet the conditions outlined in ASC 815-40 to be classified in stockholders’ equity, are not accounted for as derivatives, and are not subsequently remeasured as long as the conditions for equity classification continue to be met. The Company recorded a reduction to additional paid-in capital of approximately $22.5 million during the year ended December 31, 2020 related to the premium payments for the Capped Call Transactions. 2018 Convertible Notes In April 2018, the Company issued $14.4 million in convertible notes (“2018 Notes”) to existing shareholders of redeemable convertible and convertible preferred stock. Interest accrued on the principal balance at an annual rate of 8%. Principal and accrued interest were due at the earliest of (1) the one-year anniversary of the issuance date, (2) event of default and (3) a change of control, defined as either a merger, sale of stock or assets or other form of transaction. The 2018 Notes contained certain qualified financing and non-qualified financing redemption features which were determined to be a compound embedded derivative requiring bifurcation and separate accounting at its estimated fair value. On issuance of the 2018 Notes, the Company recognized a liability of $0.4 million for the estimated fair value of the embedded derivative and incurred $0.1 million in debt issuance costs, both of which were recorded as a debt discount associated with the 2018 Notes. In June 2018, the outstanding balance of principal and accrued interest on the 2018 Notes of $14.6 million converted into 1,067,550 and 1,997,709 shares of the Company’s Series G redeemable convertible and convertible preferred stock, respectively, at a price of $4.7565 per share. The conversion of the 2018 Notes into Series G redeemable convertible preferred stock and Series G convertible preferred stock was accounted for as an extinguishment. The extinguishment of the 2018 Notes was considered a capital transaction and accordingly, the Company recognized a $0.4 million loss on extinguishment through additional paid in capital equal to the unamortized debt discount at the date of conversion.

Convertible Preferred Stock and

Convertible Preferred Stock and Redeemable Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2020
Temporary Equity Disclosure [Abstract]
Convertible Preferred Stock and Redeemable Convertible Preferred Stock	Note 8. Convertible Preferred Stock and Redeemable Convertible Preferred Stock At December 31, 2018, convertible preferred stock and redeemable convertible preferred stock consisted of the following (in thousands, except share amounts): December 31, 2018 Shares Authorized Shares Issued and Outstanding Net Carrying Value Aggregate Liquidation Preference Series A 18,960,000 18,941,619 $ 9,161 $ 9,217 Series B 13,784,443 13,652,791 13,774 14,000 Series C 9,335,659 9,328,791 20,289 20,374 Series D 14,367,652 14,324,642 39,886 40,000 Series E 13,612,543 13,586,946 39,880 40,000 Series F 12,956,724 12,956,724 54,968 57,211 Series G 21,986,733 21,986,733 116,242 120,544 Total 105,003,754 104,778,246 $ 294,200 $ 301,346 In March 2019, the Company sold 6,350,345 shares of Series H redeemable convertible preferred stock and 3,831,766 shares of Series H convertible preferred stock at $6.8748 per share to new and existing investors for aggregate gross proceeds of $70.0 million. On July 2, 2019 and

Common Stock

Common Stock	12 Months Ended
	Dec. 31, 2020
Common Stock [Abstract]
Common Stock	Note 9. Common Stock The Company had reserved shares of common stock for issuance, on an as-converted basis, as follows: December 31, December 31, 2020 2019 Options issued and outstanding 5,809,376 9,171,756 Shares available for grant under the 2019 equity incentive plan 7,104,498 7,269,593 Outstanding restricted stock units 5,103,727 789,817 Shares available for issuance under 2019 ESPP 2,517,258 — Total 20,534,859 17,231,166

Share-based Compensation Plans

Share-based Compensation Plans	12 Months Ended
	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-based Compensation Plans	Note 10. Share-based Compensation Plans 2011 Equity Incentive Plan In 2011, the Company adopted the Equity Incentive Plan (2011 Plan) authorizing the granting of incentive stock options (ISOs) and non-statutory stock options (NSOs) to eligible participants for up to 12,987,255 shares of common stock. Under the 2011 Plan, incentive stock options and non-statutory stock options are to be granted at an exercise price that is no less than 100% of the fair value of the stock at the date of grant. Options generally vest over four years and are exercisable for up to 10 years after the date of grant. Incentive stock options granted to stockholders who own more than 10% of the outstanding stock of the Company at the time of grant must be issued at an exercise price no less than 110% of the fair value of the stock on the date of grant. The 2011 Plan has been replaced by the Company’s 2019 Plan as defined below with respect to future equity awards. 2019 Equity Incentive Plan In connection with the Company’s initial public offering, the Company adopted the 2019 Equity Incentive Plan (the “2019 Plan”). The 2019 Plan allows the Company to grant stock options, stock appreciation rights, restricted stock, restricted stock units and performance awards to participants. Subject to the terms and conditions of the 2019 Plan, the initial number of shares authorized for grants under the 2019 Plan is 8,000,000. These available shares increase annually by an amount equal to the lesser of 8,000,000 shares, 5% of the number of shares of the Company’s common stock outstanding on the immediately preceding December 31, or the number of shares determined by the Company’s board of directors. On August 4, 2020, the Company’s board of directors approved an increase of shares available for grant under the 2019 Plan by 4,293,616 shares. Activity under the Company’s stock option plan is set forth below: Number of Options Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Life (years) Aggregate Intrinsic Value (in thousands) Balances at December 31, 2019 9,171,756 5.14 6.8 $ 128,079 Options granted — — Options exercised (2,604,494 ) 3.40 Options cancelled (757,886 ) 7.40 Balances at December 31, 2020 5,809,376 5.64 5.9 82,717 Options vested and exercisable— December 31, 2020 4,232,813 3.72 5.2 67,601 There were no stock options granted in 2020. The weighted average grant date fair value of options granted during the years ended December 31, 2019 and 2018 was $8.60 per share and $3.36 per share, respectively. The aggregate intrinsic value of options exercised for the years ended December 31, 2020, 2019, and 2018 was $32.2 million, $16.2 million, and $1.4 million, respectively. The aggregate intrinsic value of options exercised is the difference between the fair value of the underlying common stock on the date of exercise and the exercise price for in-the-money stock options. RSUs A summary of RSU activity for the year ended December 31, 2020 is as follows: Restricted Stock Units Number of Shares Weighted- Average Grant Date Fair Value Aggregate Intrinsic Value (in thousands) Unvested December 31, 2019 789,817 $ 23.59 $ 14,888 Granted 5,688,318 12.54 Vested (789,853 ) 15.75 Forfeited (584,555 ) 15.64 Unvested December 31, 2020 5,103,727 $ 13.40 $ 99,640 The total fair value of RSUs vested during the year ended December 31, 2020 was $12.5 million . Employee Stock Purchase Plan In connection with the Company’s initial public offering, the Company adopted the Employee Stock Purchase Plan (ESPP). The Employee Stock Purchase Plan permits employees to purchase shares of common stock during six-month offering periods at a purchase price equal to the lesser of (1) 85% of the fair market value of a share of common stock on the first business day of such offering period and (2) 85% of the fair market value of a share of common stock on the last business day of such offering period. The initial offering period ran from May 15, 2020 through November 14, 2020. Employees purchased 91,465 shares at an average price of $10.63 for the year ended December 31, 2020. There were no shares purchased by employees during the year ended 2019. The intrinsic value of shares purchased during the year ended 2020 was $0.2 million. The intrinsic value is calculated as the difference between the market value on the date of purchase and the purchase price of the shares. As of December 31, 2020, the Company had approximately $0.3 million of unrecognized stock-based compensation cost related to purchase rights under the employee stock purchase plan, which the Company expects to recognize over a weighted average period of 0.4 years. Stock-based Compensation In determining the fair value of the stock-based awards, the Company uses the Black-Scholes option-pricing model and assumptions discussed below. Each of these inputs is subjective and generally requires significant judgment. Fair Value of Common Stock— The fair value of the shares of common stock has historically been determined by the Company’s board of directors as there was no public market for the common stock. Subsequent to our IPO, the fair value per share of common stock is the closing price of the Company’s common stock as reported on the applicable grant date. Expected Term —The expected term represents the period that the Company’s stock options are expected to be outstanding and is determined using the simplified method (based on the mid-point between the vesting date and the end of the contractual term) as the Company has concluded that its stock option exercise history does not provide a reasonable basis upon which to estimate expected term . Volatility —Because the Company was privately held and did not have an active trading market for its common stock for a sufficient period of time, the expected volatility was estimated based on the average volatility for comparable publicly-traded companies, over a period equal to the expected term of the stock option grants. Risk-free Rate —The risk-free rate assumption is based on the U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of the option. Dividends —The Company has never paid dividends on its common stock and does not anticipate paying dividends on common stock. Therefore, the Company uses an expected dividend yield of zero. The following assumptions were used to estimate the fair value of stock options granted in 2019 and 2018, as there were no stock options granted in 2020: Year Ended December 31, 2019 2018 Expected term (in years) 5.0 – 6.1 5.2 – 6.2 Expected volatility 44.2% – 47.8% 46.6% – 48.1% Average risk-free rate 1.9% – 2.6% 2.7% – 2.9% Dividend yield — — As of December 31, 2020, total unrecognized stock-based compensation expense related to options was $9.9 million, respectively. These costs are expected to be recognized over a weighted average period of 2.0 years as of December 31, 2020. As of December 31, 2020, the Company had approximately $61.7 million of unrecognized stock-based compensation expense related to RSUs, which the Company expects to recognize over the remaining weighted-average vesting period of approximately 3.1 years. Total stock-based compensation expense, excluding compensation expense related to stock sales by current and former employees, by function was as follows (in thousands): Year Ended December 31, 2020 2019 2018 Marketing $ 1,755 $ 392 $ 164 Operations and technology 10,241 3,148 1,160 Selling, general and administrative 12,326 4,171 1,587 Total $ 24,322 $ 7,711 $ 2,911 The amounts presented in the above table exclude compensation expense related to the stock sales by current and former employees. In September 2018, executives of the Company sold an aggregate of 432,270 shares of the Company’s common stock at a price of $9.0902 per share for an aggregate amount of $3.9 million to certain of the Company’s existing investors. The Company determined that the purchase price was in excess of the fair value of such shares. As a result, during the year ended December 31, 2018, the Company recorded the excess of the purchase price above fair value of $0.8 million as compensation expense in the statements of operations and a corresponding credit to additional paid-in capital. Additionally , in March 2019, executives of the Company sold an aggregate of 382,477 shares of the Company’s common stock at a price of $12.72 per share for an aggregate amount of $4.9 million to certain of the Company’s existing investors. The Company determined that the purchase price was in excess of the fair value of such shares. As a result, during the year ended December 31, 2019, the Company recorded the excess of the purchase price above fair value of $0.8 million as compensation expense within selling, general and administrative in the statement of operations and a corresponding credit to additional paid-in capital.

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases	Note 11. Leases The Company leases its corporate offices, retail spaces and authentication centers under various noncancelable operating leases with terms ranging from one year to fifteen years. The Company adopted ASU 2016-02 on January 1, 2020. At adoption, t he Company measured the lease liability at the present value of the future lease payments as of January 1, 2020, using the Company’s incremental borrowing rate for each lease. The Company derived the incremental borrowing rate by developing its own synthetic credit rating, corresponding yield curve, and the terms of each lease at the adoption date The corresponding right-of-use asset is valued at the amount of the lease liability adjusted for the remaining balance of unamortized lease incentives, prepaid rent and deferred rent as of the adoption date. The Company recorded operating lease costs of $24.7 million for the year ended December 31, 2020. The Company incurred $3.9 million of variable lease costs for the year ended December 31, 2020, which is comprised primarily of the Company’s proportionate share of operating expenses, property taxes and insurance. Rent expense under ASC 840 was $18.1 million and 10.4 million for the years ended December 31, 2019 and 2018, respectively. Maturities of operating lease liabilities by fiscal year for the Company’s operating leases are as follows (in thousands): Fiscal Year Amount 2021 23,030 2022 22,560 2023 21,168 2024 20,759 2025 21,300 Thereafter 57,458 Total future minimum payments $ 166,275 Less: Imputed interest (36,192 ) Present value of operating lease liabilities $ 130,083 As of December 31, 2020, the Company has entered into operating lease agreements that have not yet commenced. The Company will determine the classification at the commencement date for each lease, but currently expects these leases to be classified as operating leases. Pending execution of the landlord's obligations to prepare leased spaces for occupancy, the Company expects these leases to commence on various dates in the year ended December 31, 2021. The Company expects to receive a Tenant Improvement Allowance of approximately $1.8 million in the year ended December 31, 2021. As of December 31, 2020, the Company’s estimated undiscounted lease payments for leases that have not yet commenced were as follows (in thousands): Fiscal Year Lease payments for leases not yet commenced 2021 2,271 2022 3,551 2023 3,364 2024 3,445 2025 3,545 Thereafter 21,065 Total undiscounted lease payments expected to be capitalized $ 37,241 As of December 31, 2019, the Company’s future minimum lease payments under the noncancelable operating leases were as follows (in thousands): Year Ending December 31, Amount 2020 $ 20,530 2021 22,059 2022 19,610 2023 18,307 2024 17,957 Thereafter 67,208 Total future minimum payments $ 165,671 Supplemental cash flow information related to the Company’s operating leases are as follows (in thousands): Year Ended December 31, 2020 Operating cash flows used for operating leases $ 21,381 Operating lease assets obtained in exchange for operating lease liabilities $ 23,853 The weighted average remaining lease term and discount rate for the Company’s operating leases are as follows: December 31, 2020 Weighted average remaining lease term 7.3 years Weighted average discount rate 6.6 % The Company has leases for certain vehicles and equipment that are classified as finance leases. The finance lease right-of-use asset and finance lease liabilities for these vehicle and equipment leases are not material as of December 31, 2020.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 12. Commitments and Contingencies Noncancelable Purchase Commitments As of December 31, 2020, the future minimum payments under the Company’s noncancelable purchase commitments were as follows (in thousands): Year Ending December 31, Purchase Commitments 2021 $ 2,569 2022 2,420 2023 573 2024 — 2025 — Total future minimum payments $ 5,562 Other Commitments In January 2018, the Company and the University of Arizona Foundation entered into an endowment agreement (the “Endowment Agreement”) to establish a fund (the “Fund”) to create and grow a gemology degree program in the Department of Geosciences at the University of Arizona (the “University”). The Company agreed to donate a total of $2.0 million, payable in four annual installments of $0.5 million starting in January 2018. There are no conditions that the University must meet to receive the funds nor any penalties to the University for nonperformance. The Endowment Agreement directs the use of the funds but contains no binding restrictions on the use of the funds. On the execution of the Endowment Agreement, the Company recognized $1.7 million expense for the estimated fair value of the grant, using a discount rate of 10%, to selling, general and administrative expenses in the statements of operations. The Company recognized a corresponding liability for the remaining installment payments and will recognize accretion of the liability as interest expense over the remaining term of the Endowment Agreement. Interest expense related to the accretion of the grant liability was not material in the years ended December 31, 2020, 2019, and 2018. As of December 31, 2020, the outstanding liability was $0.5 million, As of December 31, 2019, the outstanding liability was $0.9 million, of which $0.5 million is included in other accrued and current liabilities on the balance sheets and $0.4 million is included in other noncurrent liabilities on the balance sheets. Contingencies From time to time, the Company is subject to, and it is presently involved in, litigation and other legal proceedings and from time to time, the Company receives inquiries from government agencies. Accounting for contingencies requires the Company to use judgment related to both the likelihood of a loss and the estimate of the amount or range of loss. The Company records a loss contingency when it is probable that a liability has been incurred and the amount of the loss can be reasonably estimated. The Company discloses material contingencies when a loss is not probable but reasonably possible. On November 14, 2018, Chanel, Inc. (“Chanel”) filed a lawsuit against the Company in the U.S. District Court for the Southern District of New York bringing various trademark and advertising-related claims under the Lanham Act and New York state law analogues. Chanel alleges, among other things, that the Company has misrepresented certain counterfeit Chanel products as authentic Chanel products, that the Company’s resale of Chanel products confuses consumers into believing that Chanel is affiliated with the Company and involved in authenticating consignors ’ ’ On September 10, 2019, a purported shareholder class action complaint was filed against the Company, its officers and directors and the underwriters of its IPO in the Superior Court of the State of California in the County of San Mateo. Three additional purported class actions, also alleging claims arising from the IPO were subsequently filed in Marin County and San Francisco County Superior Courts. The San Mateo case was voluntarily dismissed, refiled in Marin County Superior Court and consolidated with the cases there. On January 10, 2020, the Marin County plaintiffs filed a consolidated amended complaint. The plaintiffs in the San Francisco Superior Court case have filed a request for dismissal. Separately an additional purported class action was filed in the United States District Court for the Northern District of California on November 25, 2019. On February 12, 2020, a lead plaintiff was appointed in the federal action and an Amended Consolidated Complaint was filed on March 31, 2020. Defendants’ filed a demurrer and motion to strike in the state court action on March 13, 2020 and filed a motion to stay the proceedings in favor of the federal action on May 1, 2020. On August 4, 2020, the court granted defendants’ motion to stay the state court action and deferred ruling on the demurrer and motion to strike pending the outcome of the federal court action. A motion to dismiss the federal court action was filed on May 15, 2020, which motion remains pending. The state and federal complaints each allege claims under the Securities Act of 1933 on behalf of a purported class of shareholders who acquired the Company’s stock pursuant to or traceable to the registration statement for the Company’s IPO. The federal complaint also alleges claims under the Securities Exchange Act of 1934 on behalf of a purported class of shareholders who purchased the Company’s stock from June 27, 2019 through November 20, 2019. The complaints each allege, among other things, that the defendants violated federal securities laws by issuing false or misleading statements in the registration statement regarding certain of the very early stage and there can be no assurance that the Company will be successful in its defense. For this same reason, the Company cannot currently estimate the loss or the range of possible losses it may experience in connection with this litigation. Indemnifications In the ordinary course of business, the Company may provide indemnifications of varying scope and terms to vendors, directors, officers and other parties with respect to certain matters including, but not limited to, losses arising out of the breach of such agreements, intellectual property infringement claims made by third parties and other liabilities relating to or arising from the Company's various services, or its acts or omissions. The Company has not incurred any material costs as a result of such indemnifications and have not accrued any liabilities related to such obligations in its financial statements.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Note 13. Income Taxes The components of the Company’s income tax provision consisted of (in thousands): Year Ended December 31, 2020 2019 2018 Current: Federal $ — $ — $ — State 101 199 99 Total current tax expense 101 199 99 Deferred: — — — Federal — — — State — — — Total deferred tax expense — — — Total provision for income taxes $ 101 $ 199 $ 99 The reconciliation of the Federal statutory income tax provision for the Company’s effective income tax provision (in thousands): Year Ended December 31, 2020 2019 2018 Tax at federal statutory rate $ (43,259 ) $ (20,272 ) $ (15,890 ) State taxes, net of federal effect (10,315 ) (5,170 ) (4,280 ) Non-deductible items 841 1,429 537 Valuation allowance 52,834 24,212 19,732 Provision for income taxes $ 101 $ 199 $ 99 The Company’s deferred tax assets and liabilities (in thousands): December 31, 2020 2019 Deferred tax assets: Net operating loss carryforwards $ 129,333 $ 78,875 Fixed assets and intangibles 3,794 2,747 Accruals and reserves 9,155 8,430 Operating lease liabilities 35,267 — Gross deferred tax assets 177,549 90,052 Less: valuation allowance (143,214 ) (88,450 ) Total deferred tax assets 34,335 1,602 Deferred tax liabilities: Operating lease right-of-use assets (32,028 ) — Other (2,307 ) (1,602 ) Gross deferred tax liabilities (34,335 ) (1,602 ) Net deferred tax assets $ — $ — In assessing the realizability of deferred tax assets, the Company evaluates all available positive and negative evidence by considering whether it is more likely than not that some portion or all of the deferred tax assets will not be recognized. The ultimate realization of deferred tax assets is dependent upon future taxable income, future reversals of existing taxable temporary difference, taxable income in carryback years and tax-planning strategies. The Company believes it is more likely than not that the deferred tax assets in the U.S. will not be realized; accordingly, a valuation allowance has been established against our U.S. deferred tax assets. The net change in the valuation allowance for the years ended December 31, 2020 and December 31, 2019 was an increase of $54.8 million and an increase of $22.8 million, respectively. As of December 31, 2020 and 2019, the Company has a net operating loss carryforward of $485.1 million and $302.2 million for federal tax purposes, respectively, and $458.9 million and $260.7 million for state tax purposes, respectively. If not utilized, these losses will expire beginning in 2032 for California purposes. However, beginning in tax year 2018 and forward, the Federal law has changed such that net operating losses generated after December 31, 2017 may be carried forward indefinitely. Accordingly, $168.2 million of the federal net operating losses will begin to expire in 2032. However, $316.9 million of the federal net operating losses will not expire. The Tax Reform Act of 1986 limits the use of net operating losses and tax credit carryforwards in certain situations where changes occur in the stock ownership of a company. During 2019, we analyzed whether any of the reported net operating losses would be limited because of these rules. Based on our analysis we believe $3.3 million of the Federal and $2.1 million of California net operating losses will not be available to offset future taxable income because of the limitation. The reported net operating losses have been adjusted based on this analysis. The Company files tax returns as prescribed by the tax laws of the jurisdictions in which it operates. In the normal course of business, the Company is subject to examination by federal, state and local, jurisdictions, where applicable. As of December 31, 2020 and 2019, all years generally remain open to examination. Additionally, net operating loss carryforwards are subject to examination by the Internal Revenue Service and the California Franchise Tax Board for up to three years after utilization. As of December 31, 2020 and 2019, the Company does not have uncertain tax positions for which it has recorded as a liability. The Company’s policy is to include interest and penalties as a component to the statements of operations. There were no material tax penalties or interest during the years ended December 31, 2020, 2019, and 2018.

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Stockholders	Note 14. Net Loss Per Share Attributable to Common Stockholders A reconciliation of the numerator and denominator used in the calculation of the basic and diluted net loss per share attributable to common stockholders is as follows (in thousands, except share and per share data): Year Ended December 31, 2020 2019 2018 Numerator Net loss attributable to common stockholders $ (175,832 ) $ (101,784 ) $ (84,687 ) Denominator Weighted-average common shares outstanding used to calculate net loss per share attributable to common stockholders, basic and diluted 87,587,409 47,478,544 8,365,344 Net loss per share attributable to common stockholders, basic and diluted $ (2.01 ) $ (2.14 ) $ (10.12 ) The following securities were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented, because including them would have been anti-dilutive (on an as-converted basis, except the Convertible Senior Notes): December 31, 2020 2019 2018 Convertible preferred stock — — 36,862,298 Redeemable convertible preferred stock — — 16,410,256 Options to purchase common stock 5,809,376 9,171,756 9,672,102 Restricted stock units 5,103,727 789,817 — Estimated shares issuable under the Employee Stock Purchase Plan 109,729 — — Assumed conversion of the Convertible Senior Notes 9,705,454 — — Warrants to purchase convertible preferred stock — — 103,563 Warrant to purchase common stock — — 10,677 Total 20,728,286 9,961,573 63,058,896 The Notes issued in June 2020 are convertible, based on the applicable conversion rate, into cash, shares of the Company’s common stock or a combination thereof, at the Company’s election. The impact of the assumed conversion to diluted net income per share is computed using the treasury stock method.

Retirement Plan

Retirement Plan	12 Months Ended
	Dec. 31, 2020
Compensation And Retirement Disclosure [Abstract]
Retirement Plan	15. Retirement Plan The Company has a defined-contribution 401(k) retirement plan covering substantially all of its employees. Eligible employees are permitted to contribute up to an amount not to exceed an annual statutory maximum. The Company matches employee contributions at a rate of 25% of vested contributions, up to a maximum of $1,000 per participant per year. The Company’s contributions to the 401(k) plan were immaterial for the years ended December 31, 2020, 2019, and 2018.

Related Parties

Related Parties	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
Related Parties	16. Related Parties Julie Wainwright, President and Chief Executive Offer, is a board member of the RealReal Foundation, a 501(c)(3) organization, which is not a consolidated entity of the Company. During the year ended December 31, 2019, the Company donated $3.2 million to the RealReal Foundation.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of expenses during the reporting period. Significant items subject to such estimates and assumptions include those related to revenue recognition, including the returns reserve, valuation of inventory, software development costs, stock-based compensation, redemption value of redeemable convertible preferred stock, incremental borrowing rates related to lease liability, fair value of the liability component of convertible senior notes, valuation of deferred taxes, and other contingencies. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could differ from those estimates.
Net Loss per Share Attributable to Common Stockholders	Net Loss per Share Attributable to Common Stockholders The Company follows the two-class method when computing net loss per common share when shares are issued that meet the definition of participating securities. The two-class method determines net loss per common share for each class of common stock and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income (loss) available or attributable to common stockholders for the period to be allocated between common stock and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. Before the IPO, the Company’s redeemable convertible preferred stock and convertible preferred stock were considered participating securities. However, the holders of such shares did not have a contractual obligation to participate in the Company’s losses. The Company’s convertible senior notes are participating securities as they give the holders the right to receive dividends if dividend or distribution declared to the common stockholders is equal to or greater than the last reported sale price of the Company’s common stock on the trading day immediately preceding the ex-dividend date for such dividend or distribution as if the instruments had been converted into shares of common stock. No undistributed earnings were allocated to the participating securities as the contingent event is not satisfied as of the reporting date. For periods in which the Company reports net losses, diluted net loss per common share attributable to common stockholders is the same as basic net loss per common share attributable to common stockholders, because potentially dilutive common shares and assumed conversion of the convertible senior notes are not assumed to have been issued within the calculation, if their effect is anti-dilutive.
Segments	Segments The Company has one operating segment and one reportable segment as its chief operating decision maker, who is its Chief Executive Officer, reviews financial information on a consolidated basis for purposes of allocating resources and evaluating financial performance. All long-lived assets are located in the United States and substantially all revenue is attributed to consignors and buyers based in the United States.
Revenue Recognition	Revenue Recognition The Company generates revenue from the sale of pre-owned luxury goods through its online marketplace and retail stores. Consignment and Service Revenue The Company provides a service to sell pre-owned luxury goods on behalf of consignors to buyers through its online marketplace and retail stores. The Company retains a percentage of the proceeds received as payment for its consignment service, which the Company refers to as its take rate. The Company reports consignment revenue on a net basis as an agent and not the gross amount collected from the buyer. Title to the consigned goods remains with the consignor until transferred to the buyer upon purchase of the consigned goods and expiration of the allotted return period. The Company does not take title of consigned goods at any time except in certain cases where returned goods become Company-owned inventory. The Company recognizes consignment revenue upon purchase of the consigned good by the buyer as its performance obligation of providing consignment services to the consignor is satisfied at that point. Consignment revenue is recognized net of estimated returns, cancellations, buyer incentives and adjustments. The Company recognizes a returns reserve based on historical experience, which is recorded in other accrued and current liabilities on the balance sheets (see Note 5). Sales tax assessed by governmental authorities is excluded from revenue. Certain transactions provide consignors with a material right resulting from the tiered consignor commission plan. Under this plan, the amount an individual consignor receives for future sales of consigned goods may be dependent on previous consignment sales for that consignor within his/her consignment period. Accordingly, in certain consignment transactions, a small portion of the Company’s consignment revenue is allocated to such material right using the portfolio method and recorded as deferred revenue, which is recorded in other accrued and current liabilities on the balance sheets. The impact of the deferral has not been material to the financial statements. The Company charges shipping fees to buyers and has elected to treat shipping and handling activities performed after control transfers to the buyer as fulfillment activities. All outbound shipping and handling costs are accounted for as fulfillment costs in cost of consignment and service revenue at the time revenue is recognized. The Company also generates subscription revenue from monthly memberships allowing buyers early access to shop for luxury goods. The buyers receive the early access and other benefits over the term of the subscription period, which represents a single stand-ready performance obligation. Therefore, the subscription fees paid by the buyer are recognized over the monthly subscription period. Subscription revenue was not material in 2020, 2019, and 2018. Direct Revenue The Company generates direct revenue from the sale of Company-owned inventory. The Company recognizes direct revenue on a gross basis upon shipment of the purchased good to the buyer as the Company acts as the principal in the transaction. Direct revenue is recognized net of estimated returns, buyer incentives and adjustments. Sales tax assessed by governmental authorities is excluded from revenue. Cost of direct revenue is also recognized upon shipment to the buyer in an amount equal to that paid to the consignor from the original consignment sale, an amount equal to that paid as a direct purchase from a third party, or the lower of cost of the inventory purchased and its net realizable value. Incentives Incentives, which include platform-wide discounts and buyer incentives, may periodically be offered to buyers. Platform-wide discounts are made available to all buyers on the online marketplace. Buyer incentives apply to specific buyers and consist of coupons or promotions that offer credits in connection with purchases on the Company’s platform, and do not impact the commissions paid to consignors. These are treated as a reduction of consignment and service revenue and direct revenue. Additionally, the Company periodically offers commission exceptions to consignors to optimize its supply. These are treated as reduction of consignment and service revenue, and are reflected in the Company’s take rate. The Company may offer a certain type of buyer incentive in the form of site credits to buyers on current transactions to be applied towards future transactions, which are included in other accrued and current liabilities on the balance sheets. Contract Liabilities The Company’s contractual liabilities consist of deferred revenue for material rights primarily related to the tiered consignor commission plan, which are recognized as revenue using a portfolio approach based on the pattern of exercise, and certain unredeemed site credits, which were immaterial as of December 31, 2020 and December 31, 2019. Contract liabilities are recorded in other accrued and current liabilities on the balance sheets and are generally expected to be recognized within one year. Contract liabilities were immaterial as of December 31, 2020 and December 31, 2019.
Cost of Revenue	Cost of Revenue Cost of consignment and service revenue consist of shipping costs, credit card fees, packaging, customer service personnel-related costs, website hosting services, and consignor inventory adjustments relating to lost or damaged products. Cost of direct revenue consists of the cost of goods sold, credit card fees, packaging, customer service personnel-related costs, website hosting services, and inventory adjustments.
Marketing	Marketing Marketing expense is comprised of the cost of acquiring new consignors and buyers for our online platform and physical stores, including the cost of television, digital and direct mail advertising. Marketing expense also includes personnel-related costs, including stock-based compensation, of employees engaged in these activities. Advertising costs are expensed as incurred and were $45.8 million, $40.5 million, and $36.6 million in 2020, 2019, and 2018, respectively.
Operations and Technology	Operations and Technology Operations and technology expense is comprised of costs associated with the authentication, merchandising and fulfillment of goods sold through our online marketplace and retail stores, as well as general information technology expense. The principal component of operations and technology expense is personnel-related costs, including stock-based
Selling, General and Administrative	Selling, General and Administrative Selling, general and administrative expense is principally comprised of the personnel-related costs for employees involved in sales, finance and administration, and includes stock-based compensation expense. Selling, general and administrative expense also includes allocated facility and overhead costs and professional services, including accounting and legal advisors.
Stock-based Compensation	Stock-based Compensation Stock-based compensation expense related to employees and nonemployees is measured based on the grant-date fair value of the awards. Compensation expense is recognized in the statements of operations over the period during which the employee is required to perform services in exchange for the award (the vesting period of the applicable award) using the straight-line method. The Company estimates the fair value of stock options granted using the Black-Scholes option pricing model and accounts for forfeitures as they occur. The fair value of restricted stock units (“RSUs”) is estimated based on the fair market value of the Company’s common stock on the date of grant, which is determined based on the closing price of the Company’s common stock. The fair value of each purchase under the employee stock purchase plan (ESPP) is estimated at the beginning of the offering period using the Black-Scholes option pricing model. Prior to the IPO, certain employees have sold their shares of the Company’s common stock to the Company’s existing investors. In such secondary sale transactions, the Company recorded the difference in purchase price and the fair value of such shares as compensation expense within selling, general and administrative in the statements of operations and a corresponding credit to additional paid-in capital.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash The Company considers all highly liquid investments purchased with original maturities of three months or less from the purchase date to be cash equivalents. Cash equivalents primarily consist of investments in short-term money market funds and amounts invested in U.S. treasury securities. Restricted cash consists of cash deposited with a financial institution as collateral for the Company’s letters of credit for its facility leases and the Company’s credit cards. As of December 31, 2020 and December 31, 2019, the Company had no restricted cash. The following table provides a reconciliation of cash, cash equivalents and restricted cash that sum to the total of the same amounts shown in the statements of cash flows (in thousands): December 31, 2020 December 31, 2019 December 31, 2018 Cash and cash equivalents $ 350,846 $ 154,446 $ 34,393 Restricted cash — — 11,234 Total cash, cash equivalents and restricted cash $ 350,846 $ 154,446 $ 45,627
Short-term Investments	Short-term Investments The Company has classified and accounted for its short-term investments as available-for-sale which are carried at fair value on its balance sheets. Available-for-sale securities with remaining maturities of 12 months or less are classified as short term and available-for-sale securities with remaining maturities greater than 12 months are classified as long term. Available-for-sale investments are reported at fair value based on quoted market prices and other observable market data. The Company records any unrealized gains and losses within accumulated other comprehensive income (loss) as a component of stockholders’ equity (deficit), of which there were none as of December 31, 2020 and 2019. The Company adopted Accounting Standards Update (ASU) 2016-13 described below under "Recent Adopted Accounting Pronouncements." In accordance with the adopted guidance, the Company replaced the incurred loss approach with an expected loss model and the Company records allowances for available-for-sale debt securities rather than to reduce the carrying amount for other-than-temporary impairment as was followed under the other-than-temporary impairment model prior to January 1, 2020. Realized gains and losses and other-than-temporary impairments on investments are included in Other income and expense, net. As of December 31, 2020, the Company had not recorded any impairments due to credit loss.
Accounts Receivable	Accounts Receivable Accounts receivables are recorded at the amounts billed to buyers and do not bear interest. Accounts receivables result from credit card transactions, the majority of which are settled within two business days.
Inventory, Net	Inventory, Net Inventory consists of finished goods arising from goods returned after the title has transferred from the buyer to the Company as well as finished goods from direct purchases from vendors and consignors. The cost of inventory is an amount equal to that paid to the consignor or vendors. Inventory is valued at the lower of cost and net realizable value using the specific identification method and the Company records provisions, as appropriate, to write down obsolete and excess inventory to estimated net realizable value. After the inventory value is reduced, adjustments are not made to increase it from the estimated net realizable value. Our provisions to write down obsolete and excess inventory to net realizable value have not been material for 2020 and 2019. Return reserves, which reduce revenue and cost of sales, are estimated using historical experience. Liabilities for return allowances are included in other accrued and current liabilities on the balance sheets and were $18.3 million and $17.0 million as of December 31, 2020 and 2019. Included in inventory on the Company’s balance sheets are assets totaling $7.4 million and $7.1 million as of December 31, 2020 and 2019, for the rights to recover products from customers associated with its liabilities for return reserves.
Property and Equipment, Net	Property and Equipment, Net Property and equipment, net is recorded at cost less accumulated depreciation and amortization. Depreciation and amortization are recorded on a straight-line basis over the estimated useful lives of the respective assets. Repair and maintenance costs are expensed as incurred. The estimated useful lives of our assets are as follows: Proprietary software 3 years Furniture and equipment 3-5 years Vehicles 5 years Leasehold improvements Shorter of lease term or estimated useful life
Software Development Costs	Software Development Costs Proprietary software includes the costs of developing the Company’s internal proprietary business platform and automation projects. The Company capitalizes qualifying proprietary software development costs that are incurred during the application development stage. Capitalization of costs begins when two criteria are met: (1) the preliminary project stage is completed and (2) it is probable that the software will be completed and used for its intended function. Such costs are capitalized in the period incurred. Capitalization ceases and amortization begins when the software is substantially complete and ready for its intended use, including the completion of all significant testing. Costs related to preliminary project activities and post-implementation operating activities are expensed as incurred.
Impairment of Long-lived Assets	Impairment of Long-lived Assets The carrying amounts of long-lived assets, including property and equipment, net and capitalized proprietary software, are periodically reviewed for impairment whenever events or changes in circumstances indicate that the carrying value of these assets may not be recoverable or that the useful life is shorter than originally estimated. Recoverability of assets to be held and used is measured by comparing the carrying amount of assets to future undiscounted net cash flows the assets are expected to generate over their remaining life. If the assets are considered to be impaired, the amount of any impairment is measured as the difference between the carrying value and the fair value of the impaired assets. If the useful life is shorter than originally estimated, the Company amortizes the remaining carrying value over the revised shorter useful life.
Deferred Offering Costs	Deferred Offering Costs Deferred offering costs, which consist of direct incremental legal, consulting, banking and accounting fees relating to the anticipated equity offering, are capitalized and offset against proceeds upon the consummation of the offering. In the event an anticipated offering is abandoned, deferred offering costs will be expensed. In 2020, offering costs of $6.7 million related to the issuance of convertible notes was allocated to the liability and equity components based on the allocation of the proceeds. Of the total offering costs, $0.8 million was recorded as a reduction to additional paid-in capital and $5.9 million was recorded as a reduction in the carrying value of the debt on the balance sheet. In 2019, offering costs of $0.3 million were expensed. As of December 31, 2019, $5.3 million deferred offering costs were offset against the IPO proceeds within stockholders’ equity (deficit) on the balance sheets. Deferred Offering Costs Deferred offering costs, which consist of direct incremental legal, consulting, banking and accounting fees relating to the anticipated equity offering, are capitalized and offset against proceeds upon the consummation of the offering. In the event an anticipated offering is abandoned, deferred offering costs will be expensed. In 2020, offering costs of $6.7 million related to the issuance of convertible notes was allocated to the liability and equity components based on the allocation of the proceeds. Of the total offering costs, $0.8 million was recorded as a reduction to additional paid-in capital and $5.9 million was recorded as a reduction in the carrying value of the debt on the balance sheet. In 2019, offering costs of $0.3 million were expensed. As of December 31, 2019, $5.3 million deferred offering costs were offset against the IPO proceeds within stockholders’ equity (deficit) on the balance sheets.
Accretion of Redeemable Convertible Preferred Stock	Accretion of Redeemable Convertible Preferred Stock The carrying value of the redeemable convertible preferred stock that is probable of redemption is accreted to redemption value from the date of issuance to the earliest redemption date using the effective interest method until redemption is no longer probable. Increases to the carrying value of redeemable convertible preferred stock recognized in each period are charged to additional paid-in capital, or in the absence of additional paid-in capital, charged to accumulated deficit.
Convertible Preferred Stock Warrant Liability	Convertible Preferred Stock Warrant Liability The Company issued convertible preferred stock warrants in conjunction with the issuance of debt. Such warrants were recorded as other noncurrent liabilities on the balance sheets at their estimated fair value because the shares underlying the warrants may obligate the Company to transfer assets to the holders at a future date under certain circumstances such as a deemed liquidation event. The warrants are subject to re-measurement at each balance sheet date and the change in fair value, if any, is included in other expense, net. The Company continued to remeasure these warrants until the earlier of the expiration, exercise or conversion of the convertible preferred stock warrants into common warrants, which occurred upon the completion of the IPO on July 2, 2019. In connection with the completion of the IPO, the convertible preferred stock warrants automatically converted into common stock warrants. Upon conversion of the convertible preferred stock warrants, the related convertible preferred stock warrant liability was reclassified to additional paid-in capital.
Leases	Leases Prior to the adoption of ASC 842 on January 1, 2020 Leases are reviewed for classification as operating or capital leases. For operating leases, the Company recognizes rent on a straight-line basis over the term of the lease. The Company records the difference between cash payments and rent expense recognized as a deferred rent liability included in other accrued and current liabilities and other noncurrent liabilities on the balance sheets. Incentives granted under the Company’s facility leases, including allowances to fund leasehold improvements, are deferred and are recognized as adjustments to rental expense on a straight-line basis over the term of the lease. Subsequent to the adoption of ASC 842 on January 1, 2020 Contracts that have been determined to convey the right to use an identified asset are evaluated for classification as an operating or finance lease. For the Company’s operating leases, the Company records a lease liability based on the present value of the lease payments at lease inception, using the applicable incremental borrowing rate. The Company estimates the incremental borrowing rate by developing its own synthetic credit rating, corresponding yield curve, and the terms of each lease at the lease commencement date. The corresponding right-of-use asset is recorded based on the corresponding lease liability at lease inception, adjusted for payments made to the lessor at or before the commencement date, initial direct costs incurred and any tenant incentives allowed for under the lease. The Company does not include optional renewal terms or early termination provisions unless the Company is reasonably certain such options would be exercised at the inception of the lease. Operating lease right-of-use assets, current portion of operating lease liabilities, and operating lease liabilities, net of current portion are included on the Company’s balance sheet. The Company has elected the practical expedients that allows for the combination of lease components and non-lease components and to record short-term leases as lease expense on a straight-line basis on the statements of operations. Variable lease payments are recorded as expense as they are incurred. The Company has finance leases for vehicles and equipment, and the amounts of finance lease right-of-use assets and finance lease liabilities have been immaterial to date.
Convertible Senior Notes	Convertible Senior Notes Convertible debt instruments that may be settled in cash or other assets, or partially in cash, upon conversion, are separately accounted for as long-term debt and equity components (or conversion feature). The accounting applies to the Company’s convertible senior notes (the “Notes”) issued in June 2020. The debt component represents the Company’s contractual obligation to pay principal and interest and the equity component represents the Company’s option to convert the debt security into equity of the Company or the equivalent amount of cash. Upon issuance, the Company allocated the debt component on the basis of the estimated fair value of an identical debt instrument that it would issue excluding the conversion option and the remaining proceeds are allocated to the equity component. The bifurcation of the debt and equity components resulted in a debt discount for the aforementioned notes. The Company uses the interest method to amortize the debt discount to interest expense over the amortization period which is the expected life of the debt.
Capped Call Transactions	Capped Call Transactions In June 2020, in connection with the issuance of its convertible senior notes, the Company entered into Capped Call Transactions (see Note 7). The Capped Call Transactions are expected generally to reduce the potential dilution to the holders of the Company’s common stock upon any conversion of the Notes and/or offset any cash payments the Company is required to make in excess of the principal amount of converted Notes, with such reduction and/or offset subject to a cap based on the cap price. The capped calls are classified in stockholders’ equity as a reduction to additional paid-in capital and are not subsequently remeasured as long as the conditions for equity classification continue to be met.
Debt Issuance Costs	Debt Issuance Costs Debt issuance costs are amortized to interest expense over the estimated life of the related debt based on the effective interest method. The Company presents debt issuance costs on the balance sheet as a direct deduction from the associated debt. A portion of debt issuance costs incurred in connection with the Notes issued in June 2020 was related to the equity component and was recorded as a reduction to additional paid in capital and is not amortized to interest expense over the estimated life of the related debt.
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in loss in the period of enactment. The Company recognizes the effect of income tax positions only if those positions are more likely than not of being sustained. Recognized income tax positions are measured at the largest amount that is greater than 50% likely of being realized. Changes in recognition or measurement are reflected in the period in which the change in judgment occurs.
Concentrations of Credit Risks	Concentrations of Credit Risks Financial instruments that potentially subject the Company to concentrations of credit risk consist of cash and cash equivalents, restricted cash, accounts receivable, and investments. At times, such amount may exceed federally-insured limits. The Company reduces credit risk by placing its cash and cash equivalents, restricted cash, and investments with major financial institutions within the United States. As of December 31, 2020 and December 31, 2019, there were no customers that represented 10% or more of the Company’s accounts receivable balance and there were no customers that individually exceeded 10% of the Company’s total revenue for each of the years ended December 31, 2020, 2019, and 2018.
Immaterial Correction of an Error in Prior Periods	Immaterial Correction of an Error in Prior Periods During the quarter ended December 31, 2020, the Company identified an overstatement of consignment and services revenue and inventory, net as a result of an error in accounting for inventory associated with commissions paid outside of our normal payment cycle to consignors for returned merchandise. In accordance with FASB Accounting Standards Codification 250, Accounting Changes and Error Corrections The following table presents the effects of the immaterial error correction on the balance sheet and related statements of redeemable convertible preferred stock, convertible preferred stock, and stockholders’ equity (deficit) for the period indicated (in thousands): As of December 31, 2019 As previously reported Adjustments As Adjusted Current Assets: Inventory, net $ 23,599 $ (1,683 ) $ 21,916 Total current assets 408,439 (1,683 ) 406,756 Total assets $ 466,930 $ (1,683 ) $ 465,247 Stockholders' equity (deficit): Accumulated deficit (354,506 ) (1,683 ) (356,189 ) Total stockholders' equity (deficit) 338,928 (1,683 ) 337,245 Total liabilities and stockholders’ equity (deficit) $ 466,930 $ (1,683 ) 465,247 The following table presents the effects of the immaterial error correction on the statements of operations and net loss per share attributable to common stockholders, basic and diluted for the period indicated (in thousands): Year Ended December 31, 2019 As previously reported Adjustments As Adjusted Revenue: Consignment and service revenue $ 267,412 $ (1,683 ) $ 265,729 Direct revenue 50,625 — 50,625 Total revenue 318,037 (1,683 ) 316,354 Gross profit 203,206 (1,683 ) 201,523 Loss from operations (98,422 ) (1,683 ) (100,105 ) Loss before provision for income taxes (96,547 ) (1,683 ) (98,230 ) Net loss $ (96,746 ) $ (1,683 ) $ (98,429 ) Net loss attributable to common stockholders $ (100,101 ) $ (1,683 ) $ (101,784 ) Net loss per share attributable to common stockholders, basic and diluted $ (2.11 ) (0.03 ) $ (2.14 ) Shares used to compute net loss per share attributable to common stockholders, basic and diluted 47,478,544 — 47,478,544 The following table presents the effects of the immaterial error correction on the statements of comprehensive loss (in thousands): Year Ended December 31, 2019 As previously reported Adjustments As Adjusted Net loss $ (96,746 ) $ (1,683 ) $ (98,429 ) Other comprehensive income (loss), net of tax Unrealized gain (loss) on investments 32 — 32 Comprehensive loss $ (96,714 ) $ (1,683 ) (98,397 ) The following table presents the effects of the immaterial error correction on the statements of cash flows (in thousands): Year ended December 31, 2019 As previously reported Adjustments As Adjusted Cash flows from operating activities: Net loss $ (96,746 ) $ (1,683 ) $ (98,429 ) Changes in operating activities and liabilities: Inventory, net (13,244 ) 1,683 (11,561 ) Net cash used in operating activities $ (54,490 ) $ — (54,490 )
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements The Company was an emerging growth company “EGC”, as defined in the Jumpstart Our Business Startups Act of 2012 (JOBS Act). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The Company had elected to use this extended transition period to enable it to comply with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date it (1) was no longer an emerging growth company or (2) affirmatively and irrevocably opt out of the extended transition period provided in the JOBS Act. The Company chose to adopt new or revised accounting standards earlier than such time those standards apply to private companies and retain its election for the extended transition period, if early adoption is permitted for all entities. As a result, our financial statements may not be comparable to companies that comply with new or revised accounting pronouncements as of public company effective dates. Because the market value of the Company’s common stock held by non-affiliates exceeded $700 million as of June 30, 2020, the Company ceased to be an emerging growth company and was deemed a “large accelerated filer” under the Exchange Act as of December 31, 2020. As a result, the Company adopted all applicable standards retrospectively as of January 1, 2020 in this Annual Report on Form 10-K. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) The Company adopted Topic 842 on January 1, 2020 using the modified retrospective approach and applied it to all existing leases as of the adoption date, which allows for a cumulative-effect adjustment to retained earnings on the adoption date. The Company will continue to present prior period amounts under ASC 840. In addition, the Company elected the package of practical expedients permitted under the transition guidance within the new standard which does not require the Company to reassess whether contracts that expired prior to the adoption date contained an embedded lease, reassess historical lease classification, or evaluate direct costs for leases that were in effect at the adoption date. As a result of implementing this guidance, the Company recognized $110.3 million in right of use assets as of January 1, 2020. The Company also recorded $12.8 million in current operating lease liabilities and $106.2 million in operating lease liabilities, net of current portion in its balance sheet as of January 1, 2020. In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses: Measurement of Credit Losses on Financial Instruments (Topic 326) The Company adopted Topic 326 retrospectively of January 1, 2020. The adoption of this standard did not have a material impact on the Company’s financial statements as credit losses are not expected to be significant based on historical collection trends, the financial condition of payment partners, and external market factors. The Company also assessed the impact of COVID-19 on expected credit losses and it was also not material. In June 2018, the FASB issued ASU 2018-07, Compensation—Stock Compensation (Topic 718), In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820)
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In August 2020, the FASB issued 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 which simplifies accounting for convertible instruments. Under this ASU, the embedded conversion features will no longer be separated from the host contract for convertible instruments with conversion features that are not required to be accounted for as derivatives or that do not result in substantial premiums accounted for as paid-in capital. Consequently, a convertible debt instrument will be accounted for as a single liability measured at its amortized cost and a convertible preferred stock will be accounted for as a single equity instrument measured at its historical cost, as long as no other features require bifurcation and recognition as derivatives. ASU 2020-06 removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception and it also simplifies the diluted earnings per share calculation in certain areas.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Schedule of Reconciliation of Cash, Cash Equivalents and Restricted Cash	The following table provides a reconciliation of cash, cash equivalents and restricted cash that sum to the total of the same amounts shown in the statements of cash flows (in thousands): December 31, 2020 December 31, 2019 December 31, 2018 Cash and cash equivalents $ 350,846 $ 154,446 $ 34,393 Restricted cash — — 11,234 Total cash, cash equivalents and restricted cash $ 350,846 $ 154,446 $ 45,627
Estimated Useful Lives of Assets	The estimated useful lives of our assets are as follows: Proprietary software 3 years Furniture and equipment 3-5 years Vehicles 5 years Leasehold improvements Shorter of lease term or estimated useful life
Schedule Of Immaterial Correction of an Error in Prior Periods	The following table presents the effects of the immaterial error correction on the balance sheet and related statements of redeemable convertible preferred stock, convertible preferred stock, and stockholders’ equity (deficit) for the period indicated (in thousands): As of December 31, 2019 As previously reported Adjustments As Adjusted Current Assets: Inventory, net $ 23,599 $ (1,683 ) $ 21,916 Total current assets 408,439 (1,683 ) 406,756 Total assets $ 466,930 $ (1,683 ) $ 465,247 Stockholders' equity (deficit): Accumulated deficit (354,506 ) (1,683 ) (356,189 ) Total stockholders' equity (deficit) 338,928 (1,683 ) 337,245 Total liabilities and stockholders’ equity (deficit) $ 466,930 $ (1,683 ) 465,247 The following table presents the effects of the immaterial error correction on the statements of operations and net loss per share attributable to common stockholders, basic and diluted for the period indicated (in thousands): Year Ended December 31, 2019 As previously reported Adjustments As Adjusted Revenue: Consignment and service revenue $ 267,412 $ (1,683 ) $ 265,729 Direct revenue 50,625 — 50,625 Total revenue 318,037 (1,683 ) 316,354 Gross profit 203,206 (1,683 ) 201,523 Loss from operations (98,422 ) (1,683 ) (100,105 ) Loss before provision for income taxes (96,547 ) (1,683 ) (98,230 ) Net loss $ (96,746 ) $ (1,683 ) $ (98,429 ) Net loss attributable to common stockholders $ (100,101 ) $ (1,683 ) $ (101,784 ) Net loss per share attributable to common stockholders, basic and diluted $ (2.11 ) (0.03 ) $ (2.14 ) Shares used to compute net loss per share attributable to common stockholders, basic and diluted 47,478,544 — 47,478,544 The following table presents the effects of the immaterial error correction on the statements of comprehensive loss (in thousands): Year Ended December 31, 2019 As previously reported Adjustments As Adjusted Net loss $ (96,746 ) $ (1,683 ) $ (98,429 ) Other comprehensive income (loss), net of tax Unrealized gain (loss) on investments 32 — 32 Comprehensive loss $ (96,714 ) $ (1,683 ) (98,397 ) The following table presents the effects of the immaterial error correction on the statements of cash flows (in thousands): Year ended December 31, 2019 As previously reported Adjustments As Adjusted Cash flows from operating activities: Net loss $ (96,746 ) $ (1,683 ) $ (98,429 ) Changes in operating activities and liabilities: Inventory, net (13,244 ) 1,683 (11,561 ) Net cash used in operating activities $ (54,490 ) $ — (54,490 )

Cash, Cash Equivalents and Sh_2

Cash, Cash Equivalents and Short-term Investments (Tables)	12 Months Ended
	Dec. 31, 2020
Cash And Cash Equivalents [Abstract]
Summary of Estimated Value of Cash, Cash Equivalents and Short-term Investments	The following tables summarize the estimated value of the Company’s cash, cash equivalents and short-term investments (in thousands): December 31, 2020 Amortized Cost Unrealized Gain Unrealized Loss Fair Value Cash and cash equivalents: Cash $ 150,520 $ — $ — $ 150,520 Money market fund 200,326 — — 200,326 Total cash and cash equivalents $ 350,846 $ — $ — $ 350,846 Short-term investments: Corporate bonds $ 4,006 $ 11 $ — $ 4,017 Total short-term investments $ 4,006 $ 11 $ — $ 4,017 December 31, 2019 Amortized Cost Unrealized Gain Unrealized Loss Fair Value Cash and cash equivalents: Cash $ 111,319 $ — $ — $ 111,319 U.S. Treasury securities 29,981 — — 29,981 Money market fund 5,399 — — 5,399 Corporate bonds 3,749 — — 3,749 Agency bonds 2,000 — — 2,000 Commercial paper 1,998 — — 1,998 Total cash and cash equivalents $ 154,446 $ — $ — $ 154,446 Short-term investments: U.S. Treasury securities $ 151,857 $ 13 $ — $ 151,870 Corporate bonds 38,149 — (5 ) 38,144 Agency bonds 11,028 — (2 ) 11,026 Commercial paper 7,770 1 — 7,771 Total short-term investments $ 208,804 $ 14 $ (7 ) $ 208,811

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of Financial Instruments Measured at Fair Value	The following tables provide the financial instruments measured at fair value (in thousands): December 31, 2020 Level 1 Level 2 Level 3 Total Assets (1) Short-term investments: Corporate bonds $ — $ 4,017 $ — $ 4,017 Total short-term investments $ — $ 4,017 $ — $ 4,017 December 31, 2019 Level 1 Level 2 Level 3 Total Assets Cash equivalents: (1) U.S. Treasury securities $ 29,981 $ — $ — $ 29,981 Corporate bonds — 3,749 — 3,749 Agency bonds — 2,000 — 2,000 Commercial paper — 1,998 — 1,998 Total cash equivalents $ 29,981 $ 7,747 $ — $ 37,728 Short-term investments: U.S. Treasury securities $ 151,870 $ — $ — $ 151,870 Corporate bonds — 38,144 — 38,144 Agency bonds — 11,026 — 11,026 Commercial paper — 7,771 — 7,771 Total short-term investments $ 151,870 $ 56,941 $ — $ 208,811 (1) Money market funds are measured at net asset value per share and are excluded from cash equivalents in the fair value hierarchy table. The amounts of the money market funds (in thousands) were $200,326 and $5,399 at 12/31/20 and 12/31/19, respectively.
Schedule of Fair Value of Level 3 Liability Recorded	The following table presents a rollforward of the fair value of the Level 3 liability recorded at fair value (in thousands): Convertible Preferred Stock Warrant Liability Balance as of December 31, 2018 610 Changes in estimated fair value 2,100 Reclass to additional paid-in capital upon conversion to common stock warrants (2,710 ) Balance as of December 31, 2019 $ —

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consists of the following (in thousands): December 31, 2020 December 31, 2019 Proprietary software $ 24,218 $ 23,318 Furniture and equipment 27,687 21,083 Automobiles 668 718 Leasehold improvements 52,828 43,505 105,401 88,624 Less: accumulated depreciation and amortization (41,947 ) (32,793 ) Property and equipment, net $ 63,454 $ 55,831
Schedule of Other Accrued and Current Liabilities	Other accrued and current liabilities consist of the following (in thousands): December 31, 2020 December 31, 2019 Returns reserve $ 18,327 $ 17,005 Accrued compensation 13,406 11,626 Accrued marketing and outside services 10,790 6,830 Site credit liability 5,475 5,080 Accrued sales tax and other taxes 6,870 6,132 Deferred revenue 1,617 4,767 Other 5,377 3,127 Other accrued and current liabilities $ 61,862 $ 54,567

Convertible Notes (Tables)

Convertible Notes (Tables)	12 Months Ended
	Dec. 31, 2020
Amounts Recorded in Interest Expense Related to Notes	The following table sets forth the amounts recorded in interest expense related to the Notes from the date of issuance through December 31, 2020: Amount Contractual interest expense $ 2,803 Amortization of debt discount 1,843 Amortization of debt issuance costs 556 Total interest and amortization expense $ 5,202
Schedule of Future Minimum Payments Under Notes	Future minimum payments under the Notes as of December 31, 2020, are as follows: Fiscal Year Amount 2021 $ 5,175 2022 5,175 2023 5,175 2024 5,175 2025 175,088 Total future payments 195,788 Less amounts representing interest (23,288 ) Total principal amount $ 172,500
Notes as Liability Component
Schedule of Net Carrying Amount of Notes	The net carrying amount of the liability component of the Notes was as follows: December 31, 2020 Principal $ 172,500 Unamortized debt discount (17,945 ) Unamortized debt issuance costs (5,367 ) Net carrying amount $ 149,188
Notes as Equity Component
Schedule of Net Carrying Amount of Notes	The net carrying amount of the equity component of the Notes was as follows: December 31, 2020 Proceeds allocated to the conversion options (debt discount) $ 19,787 Issuance costs (767 ) Net carrying amount $ 19,020

Convertible Preferred Stock a_2

Convertible Preferred Stock and Redeemable Convertible Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2020
Temporary Equity Disclosure [Abstract]
Summary of Convertible Preferred Stock and Redeemable Convertible Preferred Stock	At December 31, 2018, convertible preferred stock and redeemable convertible preferred stock consisted of the following (in thousands, except share amounts): December 31, 2018 Shares Authorized Shares Issued and Outstanding Net Carrying Value Aggregate Liquidation Preference Series A 18,960,000 18,941,619 $ 9,161 $ 9,217 Series B 13,784,443 13,652,791 13,774 14,000 Series C 9,335,659 9,328,791 20,289 20,374 Series D 14,367,652 14,324,642 39,886 40,000 Series E 13,612,543 13,586,946 39,880 40,000 Series F 12,956,724 12,956,724 54,968 57,211 Series G 21,986,733 21,986,733 116,242 120,544 Total 105,003,754 104,778,246 $ 294,200 $ 301,346

Common Stock (Tables)

Common Stock (Tables)	12 Months Ended
	Dec. 31, 2020
Common Stock [Abstract]
Schedule of Reserved Shares of Common Stock for Issuance on Converted Basis	The Company had reserved shares of common stock for issuance, on an as-converted basis, as follows: December 31, December 31, 2020 2019 Options issued and outstanding 5,809,376 9,171,756 Shares available for grant under the 2019 equity incentive plan 7,104,498 7,269,593 Outstanding restricted stock units 5,103,727 789,817 Shares available for issuance under 2019 ESPP 2,517,258 — Total 20,534,859 17,231,166

Share-based Compensation Plans

Share-based Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Stock Option Plan Activity	Activity under the Company’s stock option plan is set forth below: Number of Options Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Life (years) Aggregate Intrinsic Value (in thousands) Balances at December 31, 2019 9,171,756 5.14 6.8 $ 128,079 Options granted — — Options exercised (2,604,494 ) 3.40 Options cancelled (757,886 ) 7.40 Balances at December 31, 2020 5,809,376 5.64 5.9 82,717 Options vested and exercisable— December 31, 2020 4,232,813 3.72 5.2 67,601
Schedule of RSUs Activity	A summary of RSU activity for the year ended December 31, 2020 is as follows: Restricted Stock Units Number of Shares Weighted- Average Grant Date Fair Value Aggregate Intrinsic Value (in thousands) Unvested December 31, 2019 789,817 $ 23.59 $ 14,888 Granted 5,688,318 12.54 Vested (789,853 ) 15.75 Forfeited (584,555 ) 15.64 Unvested December 31, 2020 5,103,727 $ 13.40 $ 99,640
Schedule of Assumptions to Estimate Fair Value of Stock Options	The following assumptions were used to estimate the fair value of stock options granted in 2019 and 2018, as there were no stock options granted in 2020: Year Ended December 31, 2019 2018 Expected term (in years) 5.0 – 6.1 5.2 – 6.2 Expected volatility 44.2% – 47.8% 46.6% – 48.1% Average risk-free rate 1.9% – 2.6% 2.7% – 2.9% Dividend yield — —
Schedule of Total Stock-based Compensation Expense, Excluding Compensation Expense Related to Stock Sales, by Function	Total stock-based compensation expense, excluding compensation expense related to stock sales by current and former employees, by function was as follows (in thousands): Year Ended December 31, 2020 2019 2018 Marketing $ 1,755 $ 392 $ 164 Operations and technology 10,241 3,148 1,160 Selling, general and administrative 12,326 4,171 1,587 Total $ 24,322 $ 7,711 $ 2,911

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Schedule of Maturities of Operating Lease Liabilities	Maturities of operating lease liabilities by fiscal year for the Company’s operating leases are as follows (in thousands): Fiscal Year Amount 2021 23,030 2022 22,560 2023 21,168 2024 20,759 2025 21,300 Thereafter 57,458 Total future minimum payments $ 166,275 Less: Imputed interest (36,192 ) Present value of operating lease liabilities $ 130,083
Schedule of Estimated Undiscounted Lease Payments for Leases	As of December 31, 2020, the Company’s estimated undiscounted lease payments for leases that have not yet commenced were as follows (in thousands): Fiscal Year Lease payments for leases not yet commenced 2021 2,271 2022 3,551 2023 3,364 2024 3,445 2025 3,545 Thereafter 21,065 Total undiscounted lease payments expected to be capitalized $ 37,241
Schedule of Future Minimum Lease Payments Under Noncancelable Operating Leases	As of December 31, 2019, the Company’s future minimum lease payments under the noncancelable operating leases were as follows (in thousands): Year Ending December 31, Amount 2020 $ 20,530 2021 22,059 2022 19,610 2023 18,307 2024 17,957 Thereafter 67,208 Total future minimum payments $ 165,671
Schedule of Supplemental Cash Flow Information Related to Operating Leases	Supplemental cash flow information related to the Company’s operating leases are as follows (in thousands): Year Ended December 31, 2020 Operating cash flows used for operating leases $ 21,381 Operating lease assets obtained in exchange for operating lease liabilities $ 23,853
Schedule of Weighted Average Remaining Lease Term and Discount Rate for Operating Leases	The weighted average remaining lease term and discount rate for the Company’s operating leases are as follows: December 31, 2020 Weighted average remaining lease term 7.3 years Weighted average discount rate 6.6 %

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Payments Under Noncancelable Purchase Commitments	As of December 31, 2020, the future minimum payments under the Company’s noncancelable purchase commitments were as follows (in thousands): Year Ending December 31, Purchase Commitments 2021 $ 2,569 2022 2,420 2023 573 2024 — 2025 — Total future minimum payments $ 5,562

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Components of Company's Tax Provision	The components of the Company’s income tax provision consisted of (in thousands): Year Ended December 31, 2020 2019 2018 Current: Federal $ — $ — $ — State 101 199 99 Total current tax expense 101 199 99 Deferred: — — — Federal — — — State — — — Total deferred tax expense — — — Total provision for income taxes $ 101 $ 199 $ 99
Schedule of Reconciliation of Company's Effective Tax Rate To Statutory Federal Rate	The reconciliation of the Federal statutory income tax provision for the Company’s effective income tax provision (in thousands): Year Ended December 31, 2020 2019 2018 Tax at federal statutory rate $ (43,259 ) $ (20,272 ) $ (15,890 ) State taxes, net of federal effect (10,315 ) (5,170 ) (4,280 ) Non-deductible items 841 1,429 537 Valuation allowance 52,834 24,212 19,732 Provision for income taxes $ 101 $ 199 $ 99
Components of Deferred Tax Assets and Liabilities	The Company’s deferred tax assets and liabilities (in thousands): December 31, 2020 2019 Deferred tax assets: Net operating loss carryforwards $ 129,333 $ 78,875 Fixed assets and intangibles 3,794 2,747 Accruals and reserves 9,155 8,430 Operating lease liabilities 35,267 — Gross deferred tax assets 177,549 90,052 Less: valuation allowance (143,214 ) (88,450 ) Total deferred tax assets 34,335 1,602 Deferred tax liabilities: Operating lease right-of-use assets (32,028 ) — Other (2,307 ) (1,602 ) Gross deferred tax liabilities (34,335 ) (1,602 ) Net deferred tax assets $ — $ —

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Schedule of Reconciliation of Numerator and Denominator Used in Calculation of Basic and Diluted Net Loss Per Share	A reconciliation of the numerator and denominator used in the calculation of the basic and diluted net loss per share attributable to common stockholders is as follows (in thousands, except share and per share data): Year Ended December 31, 2020 2019 2018 Numerator Net loss attributable to common stockholders $ (175,832 ) $ (101,784 ) $ (84,687 ) Denominator Weighted-average common shares outstanding used to calculate net loss per share attributable to common stockholders, basic and diluted 87,587,409 47,478,544 8,365,344 Net loss per share attributable to common stockholders, basic and diluted $ (2.01 ) $ (2.14 ) $ (10.12 )
Schedule of Anti-dilutive Securities Excluded from Computation of Diluted Net Loss Per Share	The following securities were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented, because including them would have been anti-dilutive (on an as-converted basis, except the Convertible Senior Notes): December 31, 2020 2019 2018 Convertible preferred stock — — 36,862,298 Redeemable convertible preferred stock — — 16,410,256 Options to purchase common stock 5,809,376 9,171,756 9,672,102 Restricted stock units 5,103,727 789,817 — Estimated shares issuable under the Employee Stock Purchase Plan 109,729 — — Assumed conversion of the Convertible Senior Notes 9,705,454 — — Warrants to purchase convertible preferred stock — — 103,563 Warrant to purchase common stock — — 10,677 Total 20,728,286 9,961,573 63,058,896

Description of Business and B_2

Description of Business and Basis of Presentation - Additional Information (Details) $ / shares in Units, $ in Thousands	Jul. 02, 2019USD ($)$ / sharesshares	Dec. 31, 2020shares	Dec. 31, 2018USD ($)shares	Dec. 31, 2019shares
Class Of Stock [Line Items]
Issuance costs | $			$ 24
Common stock, shares authorized		500,000,000		500,000,000
Redeemable convertible preferred stock outstanding			104,778,246
Initial Public Offering
Class Of Stock [Line Items]
Number of common stock issued	15,000,000
Common stock issued price per share | $ / shares	$ 20
Net proceeds from issuance of initial public offering | $	$ 315,500
Underwriting discounts and commissions | $	24,100
Issuance costs | $	$ 5,300
Common stock, shares authorized	500,000,000
Undesignated preferred stock, shares authorized for issuance	50,000,000
Redeemable convertible preferred stock outstanding	114,960,357
Convertible preferred stock converted into common stock	58,363,606
Description of reverse stock split		On June 13, 2019, the Company effected a reverse split of shares of the Company’s common stock on a 1-for-2 basis
Reverse stock split ratio		0.5
Initial Public Offering | Common Stock Warrants
Class Of Stock [Line Items]
Conversion of preferred stock warrants into common stock warrants	103,563
Underwriters' Option to Purchase Additional Shares
Class Of Stock [Line Items]
Number of common stock issued	2,250,000
Common stock issued price per share | $ / shares	$ 20

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020USD ($)SegmentCustomer	Dec. 31, 2019USD ($)Customer	Dec. 31, 2018USD ($)Customer	Jun. 30, 2020USD ($)	Jan. 01, 2020USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of operating segment | Segment	1
Number of reportable segment | Segment	1
Advertising expense	$ 45,800,000	$ 40,500,000	$ 36,600,000
Restricted cash	0	0	11,234,000
Impairments due to credit loss	0
Unrealized gains and losses within accumulated other comprehensive income (loss)	0	0
Rights to recover products from customers	7,400,000	7,100,000
Equity component of convertible senior notes, net of issuance costs	19,020,000
Deferred offering costs		300,000
Deferred offering cost offset against IPO proceeds		5,300,000
Total revenue	(299,949,000)	(316,354,000)	(213,732,000)
Inventory, net	(42,321,000)	(21,916,000)
Market value of common stock held by non-affiliates				$ 700,000,000
Right-of-use asset	118,136,000				$ 110,300,000
Current operating lease liabilities	14,999,000				12,800,000
Operating lease liabilities, net of current portion	$ 115,084,000				$ 106,200,000
ASU 2016-02
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, early adoption	true
Date accounting standards update was adopted	Jan. 1, 2020
Change in accounting principle, accounting standards update, transition option elected [Extensible List]	us-gaap:AccountingStandardsUpdate201602RetrospectiveMember
ASU 2016-13
Summary Of Significant Accounting Policies [Line Items]
Date accounting standards update was adopted	Jan. 1, 2020
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, immaterial effect	true
ASU 2018-07
Summary Of Significant Accounting Policies [Line Items]
Date accounting standards update was adopted	Jan. 1, 2020
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, immaterial effect	true
ASU 2018-13
Summary Of Significant Accounting Policies [Line Items]
Date accounting standards update was adopted	Jan. 1, 2020
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, immaterial effect	true
Adjustments
Summary Of Significant Accounting Policies [Line Items]
Total revenue		1,683,000
Inventory, net		1,683,000
Consignment and Service Revenue
Summary Of Significant Accounting Policies [Line Items]
Total revenue	$ (247,326,000)	(265,729,000)	$ (180,607,000)
Consignment and Service Revenue | Adjustments
Summary Of Significant Accounting Policies [Line Items]
Total revenue		$ 1,683,000
Accounts Receivable
Summary Of Significant Accounting Policies [Line Items]
Number of major customers | Customer	0	0
Total Revenue
Summary Of Significant Accounting Policies [Line Items]
Number of major customers | Customer	0	0	0
2025 Convertible Senior Notes
Summary Of Significant Accounting Policies [Line Items]
Debt offering costs	$ 6,700,000
Equity component of convertible senior notes, net of issuance costs	800,000
Liability component recorded as a reduction in carrying value of debt	5,900,000
Other Accrued and Current Liabilities
Summary Of Significant Accounting Policies [Line Items]
Inventory return reserves allowances	18,300,000	$ 17,000,000
Proprietary software
Summary Of Significant Accounting Policies [Line Items]
Research and development expense	9,000,000	$ 9,300,000	$ 5,700,000
Common Stock
Summary Of Significant Accounting Policies [Line Items]
Dividend or distribution declared	$ 0

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Cash and cash equivalents	$ 350,846,000	$ 154,446,000	$ 34,393,000
Restricted cash	0	0	11,234,000
Total cash, cash equivalents and restricted cash	$ 350,846,000	$ 154,446,000	$ 45,627,000	$ 20,660,000

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Estimated Useful Lives of Assets (Details)	12 Months Ended
	Dec. 31, 2020
Proprietary software
Property Plant And Equipment [Line Items]
Property and equipment, useful life	3 years
Furniture and equipment | Maximum
Property Plant And Equipment [Line Items]
Property and equipment, useful life	5 years
Furniture and equipment | Minimum
Property Plant And Equipment [Line Items]
Property and equipment, useful life	3 years
Vehicles
Property Plant And Equipment [Line Items]
Property and equipment, useful life	5 years
Leasehold improvements
Property Plant And Equipment [Line Items]
Property and equipment, estimated useful lives	Shorter of lease term or estimated useful life

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Summary of Effects of Immaterial Error Correction on Balance Sheet and Statements of Stockholders' Equity (Deficit) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current assets
Inventory, net	$ 42,321	$ 21,916
Total current assets	421,469	406,756
Total assets	605,109	465,247
Stockholders’ equity:
Accumulated deficit	(532,021)	(356,189)
Total stockholders' equity (deficit)	191,293	337,245	$ (257,690)	$ (176,986)
Total liabilities and stockholders’ equity (deficit)	$ 605,109	465,247
As Previously Reported
Current assets
Inventory, net		23,599
Total current assets		408,439
Total assets		466,930
Stockholders’ equity:
Accumulated deficit		(354,506)
Total stockholders' equity (deficit)		338,928
Total liabilities and stockholders’ equity (deficit)		466,930
Adjustments
Current assets
Inventory, net		(1,683)
Total current assets		(1,683)
Total assets		(1,683)
Stockholders’ equity:
Accumulated deficit		(1,683)
Total stockholders' equity (deficit)		(1,683)
Total liabilities and stockholders’ equity (deficit)		$ (1,683)

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Summary of Effects of Immaterial Error Correction on Statements of Operations and Net Loss per Share Attributable to Common Stockholders, Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue:
Total revenue	$ 299,949	$ 316,354	$ 213,732
Gross profit	187,567	201,523	136,918
Loss from operations	(172,816)	(100,105)	(73,904)
Loss before provision for income taxes	(175,731)	(98,230)	(75,666)
Net loss	(175,832)	(98,429)	(75,765)
Net loss attributable to common stockholders	$ (175,832)	$ (101,784)	$ (84,687)
Net loss per share attributable to common stockholders, basic and diluted	$ (2.01)	$ (2.14)	$ (10.12)
Shares used to compute net loss per share attributable to common stockholders, basic and diluted	87,587,409	47,478,544	8,365,344
As Previously Reported
Revenue:
Total revenue		$ 318,037
Gross profit		203,206
Loss from operations		(98,422)
Loss before provision for income taxes		(96,547)
Net loss		(96,746)
Net loss attributable to common stockholders		$ (100,101)
Net loss per share attributable to common stockholders, basic and diluted		$ (2.11)
Shares used to compute net loss per share attributable to common stockholders, basic and diluted		47,478,544
Adjustments
Revenue:
Total revenue		$ (1,683)
Gross profit		(1,683)
Loss from operations		(1,683)
Loss before provision for income taxes		(1,683)
Net loss		(1,683)
Net loss attributable to common stockholders		$ (1,683)
Net loss per share attributable to common stockholders, basic and diluted		$ (0.03)
Consignment and Service Revenue
Revenue:
Total revenue	$ 247,326	$ 265,729	$ 180,607
Consignment and Service Revenue | As Previously Reported
Revenue:
Total revenue		267,412
Consignment and Service Revenue | Adjustments
Revenue:
Total revenue		(1,683)
Direct Revenue
Revenue:
Total revenue	$ 52,623	50,625	$ 33,125
Direct Revenue | As Previously Reported
Revenue:
Total revenue		$ 50,625

Summary of Significant Accoun_9

Summary of Significant Accounting Policies - Summary of Effects of Immaterial Error Correction on Statements of Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Net loss	$ (175,832)	$ (98,429)	$ (75,765)
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on investments	4	32	(19)
Comprehensive loss	$ (175,828)	(98,397)	$ (75,784)
As Previously Reported
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Net loss		(96,746)
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on investments		32
Comprehensive loss		(96,714)
Adjustments
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Net loss		(1,683)
Other comprehensive income (loss), net of tax:
Comprehensive loss		$ (1,683)

Summary of Significant Accou_10

Summary of Significant Accounting Policies - Summary of Effects of Immaterial Error Correction on Statements of Cashflows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net loss	$ (175,832)	$ (98,429)	$ (75,765)
Changes in operating assets and liabilities:
Inventory, net	(20,405)	(11,561)	(3,741)
Net cash used in operating activities	$ (134,419)	(54,490)	$ (47,195)
As Previously Reported
Cash flows from operating activities:
Net loss		(96,746)
Changes in operating assets and liabilities:
Inventory, net		(13,244)
Net cash used in operating activities		(54,490)
Adjustments
Cash flows from operating activities:
Net loss		(1,683)
Changes in operating assets and liabilities:
Inventory, net		$ 1,683

Cash, Cash Equivalents and Sh_3

Cash, Cash Equivalents and Short-term Investments - Summary of Estimated Value of Cash, Cash Equivalents and Short-term Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Cash And Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost	$ 350,846	$ 154,446
Cash and cash equivalents, fair value	350,846	154,446
Short-term investments, amortized cost	4,006	208,804
Short-term investments, unrealized gain	11	14
Short-term investments, unrealized loss		(7)
Short-term investments, fair value	4,017	208,811
Cash
Cash And Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost	150,520	111,319
Cash and cash equivalents, fair value	150,520	111,319
Money Market Fund
Cash And Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost	200,326	5,399
Cash and cash equivalents, fair value	200,326	5,399
Corporate Bonds
Cash And Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost		3,749
Cash and cash equivalents, fair value		3,749
Short-term investments, amortized cost	4,006	38,149
Short-term investments, unrealized gain	11
Short-term investments, unrealized loss		(5)
Short-term investments, fair value	$ 4,017	38,144
Agency Bonds
Cash And Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost		2,000
Cash and cash equivalents, fair value		2,000
Short-term investments, amortized cost		11,028
Short-term investments, unrealized loss		(2)
Short-term investments, fair value		11,026
Commercial Paper
Cash And Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost		1,998
Cash and cash equivalents, fair value		1,998
Short-term investments, amortized cost		7,770
Short-term investments, unrealized gain		1
Short-term investments, fair value		7,771
U.S. Treasury Securities
Cash And Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost		29,981
Cash and cash equivalents, fair value		29,981
Short-term investments, amortized cost		151,857
Short-term investments, unrealized gain		13
Short-term investments, fair value		$ 151,870

Cash, Cash Equivalents and Sh_4

Cash, Cash Equivalents and Short-term Investments - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Maximum
Cash And Cash Equivalents [Line Items]
Short term investments contractual maturity term	1 year	1 year

Fair Value Measurement - Additi

Fair Value Measurement - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Jun. 30, 2020	Jun. 15, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Asset transfers Level 1 to Level 2	$ 0	$ 0
Asset transfers Level 2 to Level 1	0	0
Asset transfers into Level 3	0	0
Asset transfers out of Level 3	0	0
Liabilities transfers Level 1 to Level 2	0	0
Liabilities transfers Level 2 to Level 1	0	0
Liability transfers into Level 3	0	0
Liability transfers out of Level 3	0	$ 0
Aggregate face amount	172,500,000
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Estimated fair value based on market price	184,400,000
Convertible Senior Notes | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Aggregate face amount	$ 172,500,000
3.00% Convertible Senior Notes Due 2025
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Notes interest rate	3.00%		3.00%	3.00%
Fair value of liability	$ 152,700,000			$ 152,700,000
Discount on initial issuance				$ 19,800,000
Aggregate face amount			$ 172,500,000

Fair Value Measurement - Schedu

Fair Value Measurement - Schedule of Financial Instruments Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets
Cash equivalents	$ 350,846	$ 154,446
Short-term investments	4,017	208,811
Recurring
Assets
Cash equivalents		37,728
Short-term investments	4,017	208,811
Recurring | Level 1
Assets
Cash equivalents		29,981
Short-term investments		151,870
Recurring | Level 2
Assets
Cash equivalents		7,747
Short-term investments	4,017	56,941
Recurring | U.S. Treasury Securities
Assets
Cash equivalents		29,981
Short-term investments		151,870
Recurring | U.S. Treasury Securities | Level 1
Assets
Cash equivalents		29,981
Short-term investments		151,870
Recurring | Corporate Bonds
Assets
Cash equivalents		3,749
Short-term investments	4,017	38,144
Recurring | Corporate Bonds | Level 2
Assets
Cash equivalents		3,749
Short-term investments	$ 4,017	38,144
Recurring | Agency Bonds
Assets
Cash equivalents		2,000
Short-term investments		11,026
Recurring | Agency Bonds | Level 2
Assets
Cash equivalents		2,000
Short-term investments		11,026
Recurring | Commercial Paper
Assets
Cash equivalents		1,998
Short-term investments		7,771
Recurring | Commercial Paper | Level 2
Assets
Cash equivalents		1,998
Short-term investments		$ 7,771

Fair Value Measurement - Sche_2

Fair Value Measurement - Schedule of Financial Instruments Measured at Fair Value (Parenthetical) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents, fair value	$ 350,846	$ 154,446
Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents, fair value		37,728
Recurring | Money Market Fund
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents, fair value	$ 200,326	$ 5,399

Fair Value Measurement - Sche_3

Fair Value Measurement - Schedule of Fair Value of Level 3 Liability Recorded (Details) - Convertible Preferred Stock Warrant Liability $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 610
Changes in estimated fair value	2,100
Reclass to additional paid-in capital upon conversion to common stock warrants	$ (2,710)

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 105,401	$ 88,624
Less: accumulated depreciation and amortization	(41,947)	(32,793)
Property and equipment, net	63,454	55,831
Proprietary Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	24,218	23,318
Furniture And Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	27,687	21,083
Automobiles
Property Plant And Equipment [Line Items]
Property and equipment, gross	668	718
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 52,828	$ 43,505

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Depreciation and amortization expense on property and equipment	$ 18.8	$ 13.4	$ 9.3
Proprietary Software
Property Plant And Equipment [Line Items]
Fully depreciated proprietary software taken out of service	$ 7.9

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Other Accrued and Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Returns reserve	$ 18,327	$ 17,005
Accrued compensation	13,406	11,626
Accrued marketing and outside services	10,790	6,830
Site credit liability	5,475	5,080
Accrued sales tax and other taxes	6,870	6,132
Deferred revenue	1,617	4,767
Other	5,377	3,127
Other accrued and current liabilities	$ 61,862	$ 54,567

Debt and Convertible Preferre_2

Debt and Convertible Preferred Stock Warrants - Additional Information (Details) - USD ($)	Jul. 26, 2019	Jul. 31, 2019	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2013
Debt Disclosure [Line Items]
Long-term debt, gross					$ 195,788,000	$ 195,788,000
Interest expense related to term loans					$ 5,202,000	$ 0	$ 300,000	$ 700,000
Warrants outstanding					0	0	0
Letter of Credit
Debt Disclosure [Line Items]
Debt instrument, maturity date								Aug. 1, 2019
Line of credit								$ 1,500,000
IPO
Debt Disclosure [Line Items]
Debt, success fee		$ 300,000
Series G Convertible Preferred Stock
Debt Disclosure [Line Items]
Debt, success fee			$ 100,000
Series B Convertible Preferred Stock
Debt Disclosure [Line Items]
Outstanding preferred stock warrants exercised (in shares)					131,652	131,652
Exercise price of warrants (in dollars per share)					$ 1.03	$ 1.03
Series C Convertible Preferred Stock
Debt Disclosure [Line Items]
Outstanding preferred stock warrants exercised (in shares)					6,868	6,868
Exercise price of warrants (in dollars per share)					$ 2.18	$ 2.18
Series D Convertible Preferred Stock
Debt Disclosure [Line Items]
Outstanding preferred stock warrants exercised (in shares)					43,010	43,010
Exercise price of warrants (in dollars per share)					$ 2.79	$ 2.79
Series E Convertible Preferred Stock
Debt Disclosure [Line Items]
Outstanding preferred stock warrants exercised (in shares)					25,597	25,597
Exercise price of warrants (in dollars per share)					$ 2.93	$ 2.93
Convertible Preferred Stock
Debt Disclosure [Line Items]
Warrant term						10 years
Term Loan Facility
Debt Disclosure [Line Items]
Maximum borrowing capacity										$ 5,000,000
Increase in borrowing capacity						$ 11,600,000
Debt instrument required covenants percentage on forecasted gross revenue						80.00%
Debt, combined success fee								$ 300,000
Debt, additional success fee				$ 100,000
Net cash proceeds from subordinated debt securities				$ 50,000,000
Term Loans
Debt Disclosure [Line Items]
Long-term debt, gross									$ 15,000,000
Repayments on loans	$ 6,500,000
Term Loan I
Debt Disclosure [Line Items]
Long-term debt, gross									$ 7,500,000
Debt instrument, maturity date								Jan. 31, 2021	Jan. 31, 2019
Number of equal monthly installments						30 equal monthly installments
Variable annual interest rate								0.35%	0.10%
Term Loan II
Debt Disclosure [Line Items]
Long-term debt, gross									$ 7,500,000
Debt instrument, maturity date									Jan. 1, 2020

Convertible Notes - Additional

Convertible Notes - Additional Information (Details)	Jun. 10, 2020$ / shares	Jun. 30, 2020USD ($)$ / sharesshares	Jun. 30, 2018USD ($)$ / sharesshares	Apr. 30, 2018USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2020USD ($)d	Dec. 31, 2018USD ($)	Jun. 15, 2020USD ($)
Debt Instrument [Line Items]
Aggregate principal amount					$ 172,500,000	$ 172,500,000
Purchase of capped call transactions						22,546,000
Equity component of convertible senior notes, net of issuance costs						19,020,000
Payment to counterparties for purchased calls		$ 22,500,000
Common stock subject to adjustment and exercisable upon conversion of initial notes | shares		9,705,454
Cap price of capped transactions | $ / shares	27.88
Derivative cap price as percentage on common stock price per share	100.00%
Closing price of common stock per share | $ / shares	$ 13.94
Reduction to additional paid premium payments for capped call transactions						$ 22,500,000
Loss on extinguishment of convertible notes							$ 370,000
2025 Convertible Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount		$ 172,500,000
Notes interest rate		3.00%			3.00%	3.00%		3.00%
Debt instrument, maturity date						Jun. 15, 2025
Proceeds from issuance of convertible senior notes, net of issuance costs		$ 165,800,000
Purchase of capped call transactions		$ 22,500,000
Notes frequency of periodic payment						semi-annually
Number of shares per $1,000 principal amount | shares		56.2635
Initial conversion price | $ / shares		$ 17.77
Notes, threshold percentage of stock price trigger						130.00%
Notes, threshold trading days | d						20
Notes, threshold consecutive trading days | d						30
Percentage on aggregate principal amount of notes to be payable upon the event of default						25.00%
Interest rate used to compute initial fair value of liability						5.67%
Fair value of liability					$ 152,700,000	$ 152,700,000		$ 152,700,000
Debt issuance costs					6,700,000	6,700,000
Equity component of convertible senior notes, net of issuance costs						800,000
Liability component recorded as a reduction in carrying value of debt					$ 5,900,000	$ 5,900,000
Amortization period						5 years
Effective Interest rate					6.40%
2025 Convertible Senior Notes | Purchased Calls
Debt Instrument [Line Items]
Expiration date						Jun. 12, 2025
2025 Convertible Senior Notes | Conversion Option One
Debt Instrument [Line Items]
Notes, threshold percentage of stock price trigger						130.00%
Notes, threshold trading days | d						20
Notes, threshold consecutive trading days | d						30
2025 Convertible Senior Notes | Conversion Option Two
Debt Instrument [Line Items]
Notes, threshold percentage of stock price trigger						98.00%
Notes, threshold consecutive trading days | d						5
Notes, threshold trading days | d						5
2025 Convertible Senior Notes | Initial Purchasers
Debt Instrument [Line Items]
Aggregate principal amount		$ 22,500,000
2018 Convertible Notes
Debt Instrument [Line Items]
Notes interest rate				8.00%
Proceeds from issuance of convertible senior notes, net of issuance costs				$ 14,400,000
Initial conversion price | $ / shares			$ 4.7565
Debt issuance costs				100,000
Liability recognized on estimated fair value of embedded derivative				$ 400,000
Principal and accrued interest on convertible notes			$ 14,600,000
Loss on extinguishment of convertible notes			$ 400,000
2018 Convertible Notes | Series G Redeemable Convertible Preferred Stock
Debt Instrument [Line Items]
Issuance of redeemable convertible preferred stock | shares			1,067,550
2018 Convertible Notes | Convertible Preferred Stock
Debt Instrument [Line Items]
Issuance of redeemable convertible preferred stock | shares			1,997,709

Convertible Notes - Schedule of

Convertible Notes - Schedule of Net Carrying Amount of Liability Component of Notes (Details)	Dec. 31, 2020USD ($)
Debt Disclosure [Line Items]
Principal	$ 172,500,000
Notes as Liability Component
Debt Disclosure [Line Items]
Principal	172,500,000
Unamortized debt discount	(17,945,000)
Unamortized debt issuance costs	(5,367,000)
Net carrying amount	$ 149,188,000

Convertible Notes - Schedule _2

Convertible Notes - Schedule of Net Carrying Amount of Equity Component of Notes (Details) - Notes as Equity Component $ in Thousands	Dec. 31, 2020USD ($)
Debt Disclosure [Line Items]
Proceeds allocated to the conversion options (debt discount)	$ 19,787
Issuance costs	(767)
Net carrying amount	$ 19,020

Convertible Notes - Amounts Rec

Convertible Notes - Amounts Recorded in Interest Expense Related to Notes (Details) - USD ($) $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
Contractual interest expense	$ 2,803
Amortization of debt discount	1,843
Amortization of debt issuance costs	556
Total interest and amortization expense	$ 5,202	$ 0	$ 300	$ 700

Convertible Notes - Schedule _3

Convertible Notes - Schedule of Future Minimum Payments Under Notes (Details) $ in Thousands	Dec. 31, 2020USD ($)
Debt Disclosure [Abstract]
2021	$ 5,175
2022	5,175
2023	5,175
2024	5,175
2025	175,088
Total future payments	195,788
Less amounts representing interest	(23,288)
Total principal amount	$ 172,500

Convertible Preferred Stock a_3

Convertible Preferred Stock and Redeemable Convertible Preferred Stock - Summary of Convertible Preferred Stock and Redeemable Convertible Preferred Stock (Details) $ in Thousands	Dec. 31, 2018USD ($)shares
Temporary Equity [Line Items]
Shares Authorized	105,003,754
Shares Issued	104,778,246
Shares Outstanding	104,778,246
Net Carrying Value | $	$ 294,200
Aggregate Liquidation Preference | $	$ 301,346
Series A
Temporary Equity [Line Items]
Shares Authorized	18,960,000
Shares Issued	18,941,619
Shares Outstanding	18,941,619
Net Carrying Value | $	$ 9,161
Aggregate Liquidation Preference | $	$ 9,217
Series B
Temporary Equity [Line Items]
Shares Authorized	13,784,443
Shares Issued	13,652,791
Shares Outstanding	13,652,791
Net Carrying Value | $	$ 13,774
Aggregate Liquidation Preference | $	$ 14,000
Series C
Temporary Equity [Line Items]
Shares Authorized	9,335,659
Shares Issued	9,328,791
Shares Outstanding	9,328,791
Net Carrying Value | $	$ 20,289
Aggregate Liquidation Preference | $	$ 20,374
Series D
Temporary Equity [Line Items]
Shares Authorized	14,367,652
Shares Issued	14,324,642
Shares Outstanding	14,324,642
Net Carrying Value | $	$ 39,886
Aggregate Liquidation Preference | $	$ 40,000
Series E
Temporary Equity [Line Items]
Shares Authorized	13,612,543
Shares Issued	13,586,946
Shares Outstanding	13,586,946
Net Carrying Value | $	$ 39,880
Aggregate Liquidation Preference | $	$ 40,000
Series F
Temporary Equity [Line Items]
Shares Authorized	12,956,724
Shares Issued	12,956,724
Shares Outstanding	12,956,724
Net Carrying Value | $	$ 54,968
Aggregate Liquidation Preference | $	$ 57,211
Series G
Temporary Equity [Line Items]
Shares Authorized	21,986,733
Shares Issued	21,986,733
Shares Outstanding	21,986,733
Net Carrying Value | $	$ 116,242
Aggregate Liquidation Preference | $	$ 120,544

Convertible Preferred Stock a_4

Convertible Preferred Stock and Redeemable Convertible Preferred Stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Jul. 02, 2019	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Temporary Equity [Line Items]
Aggregate gross proceeds			$ 26,283	$ 9,627
Initial Public Offering
Temporary Equity [Line Items]
Convertible preferred stock converted into common stock	58,363,606
Series H
Temporary Equity [Line Items]
Redeemable convertible preferred stock issued		6,350,345
Convertible preferred stock issued		3,831,766
Preferred stock par value		$ 6.8748
Aggregate gross proceeds		$ 70,000

Common Stock - Schedule of Rese

Common Stock - Schedule of Reserved Shares of Common Stock for Issuance on Converted Basis (Details) - shares	Dec. 31, 2020	Dec. 31, 2019
Class Of Stock [Line Items]
Common stock reserved for future issuance	20,534,859	17,231,166
2019 Equity Incentive Plan
Class Of Stock [Line Items]
Common stock reserved for future issuance	7,104,498	7,269,593
2019 Employee Stock Purchase Plan
Class Of Stock [Line Items]
Common stock reserved for future issuance	2,517,258
Outstanding Restricted Stock Units
Class Of Stock [Line Items]
Common stock reserved for future issuance	5,103,727	789,817
Options Issued and Outstanding
Class Of Stock [Line Items]
Common stock reserved for future issuance	5,809,376	9,171,756

Share-based Compensation Plan_2

Share-based Compensation Plans - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		12 Months Ended
	Mar. 31, 2019	Sep. 30, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2011	Aug. 04, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted			0
Share-based compensation arrangement by share-based payment award, options, grants in period, weighted average grant date fair value				$ 8.60	$ 3.36
Weighted average period expect to recognized			2 years
Unrecognized stock-based compensation expense			$ 9.9
Selling, General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Compensation expense				$ 0.8	$ 0.8
Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares issued in transaction	382,477	432,270
Sale of stock, price per share	$ 12.72	$ 9.0902
Sale of stock, aggregate amount	$ 4.9	$ 3.9
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized			1,750,000
Annual increase in number of shares, percentage of shares of outstanding common stock			1.00%
Increase in shares available for grant							858,723
Aggregate intrinsic value of options exercised			$ 0.2
Number of shares purchased			91,465	0
Average price of shares purchased			$ 10.63
Unrecognized compensation costs			$ 0.3
Weighted average period expect to recognized			4 months 24 days
Employee Stock Purchase Plan | First Business Day
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted as percentage on fair value of stock			85.00%
Employee Stock Purchase Plan | Last Business Day
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted as percentage on fair value of stock			85.00%
Maximum | Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Annual increase in available number of authorized shares			1,750,000
RSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vested in period, fair value			$ 12.5
Unrecognized compensation costs			$ 61.7
Weighted average period expect to recognized			3 years 1 month 6 days
2011 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period						4 years
Percentage of maximum incentive stock options granted to stockholders						10.00%
2011 Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options exercisable period						10 years
2011 Plan | Incentive and Non-statutory Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized						12,987,255
2011 Plan | Incentive and Non-statutory Stock Options | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted as percentage on fair value of stock						100.00%
2011 Plan | Incentive Stock Options | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted as percentage on fair value of stock						110.00%
2019 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized			8,000,000
Annual increase in number of shares, percentage of shares of outstanding common stock			5.00%
Increase in shares available for grant							4,293,616
Aggregate intrinsic value of options exercised			$ 32.2	$ 16.2	$ 1.4
2019 Equity Incentive Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Annual increase in available number of authorized shares			8,000,000

Share-based Compensation Plan_3

Share-based Compensation Plans - Schedule of Stock Option Plan Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options, Options granted	0
2019 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding, Balance	9,171,756
Number of Options, Options exercised	(2,604,494)
Number of Options, Options cancelled	(757,886)
Number of Options Outstanding, Balance	5,809,376	9,171,756
Number of Options, Options vested and exercisable	4,232,813
Weighted Average Exercise Price Per Share, Balance	$ 5.14
Weighted Average Exercise Price Per Share, Options exercised	3.40
Weighted Average Exercise Price Per Share, Options cancelled	7.40
Weighted Average Exercise Price Per Share, Balance	5.64	$ 5.14
Weighted Average Exercise Price Per Share, Options vested and exercisable	$ 3.72
Weighted Average Remaining Contractual Life (years), Balance	5 years 10 months 24 days	6 years 9 months 18 days
Weighted Average Remaining Contractual Life (years), Options vested and exercisable	5 years 2 months 12 days
Aggregate Intrinsic Value, Balance	$ 82,717	$ 128,079
Aggregate Intrinsic Value, Options vested and exercisable	$ 67,601

Share-based Compensation Plan_4

Share-based Compensation Plans - Schedule of RSUs Activity (Details) - RSUs - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares Unvested, Balance	789,817
Number of Shares Unvested, Granted	5,688,318
Number of Shares Unvested, Vested	(789,853)
Number of Shares Unvested, Forfeited	(584,555)
Number of Shares Unvested, Balance	5,103,727
Weighted-Average Grant Date Fair Value, Balance	$ 23.59
Weighted-Average Grant Date Fair Value, Granted	12.54
Weighted-Average Grant Date Fair Value, Vested	15.75
Weighted-Average Grant Date Fair Value, Forfeited	15.64
Weighted-Average Grant Date Fair Value, Balance	13.40
Aggregate Intrinsic Value, Balance	$ 99,640,000	$ 14,888,000

Share-based Compensation Plan_5

Share-based Compensation Plans - Schedule of Assumptions to Estimate Fair Value of Stock Options (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility, minimum	44.20%	46.60%
Expected volatility, maximum	47.80%	48.10%
Average risk-free rate, minimum	1.90%	2.70%
Average risk-free rate, maximum	2.60%	2.90%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years	5 years 2 months 12 days
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years 1 month 6 days	6 years 2 months 12 days

Share-based Compensation Plan_6

Share-based Compensation Plans - Schedule of Total Stock-based Compensation Expense, Excluding Compensation Expense Related to Stock Sales, by Function (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 24,322	$ 7,711	$ 2,911
Marketing
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	1,755	392	164
Operations and Technology
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	10,241	3,148	1,160
Selling, General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 12,326	$ 4,171	$ 1,587

Leases - Additional Information

Leases - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases [Line Items]
Operating lease costs	$ 24.7
Variable lease costs	$ 3.9
Rent expense from operating leases		$ 18.1	$ 10.4
Operating lease agreements that not yet commenced, description	As of December 31, 2020, the Company has entered into operating lease agreements that have not yet commenced.
Expects to receive a Tenant Improvement Allowance	$ 1.8
Estimated undiscounted lease payments not yet commenced, description	As of December 31, 2020, the Company’s estimated undiscounted lease payments for leases that have not yet commenced
Minimum
Leases [Line Items]
Operating lease term	1 year
Maximum
Leases [Line Items]
Operating lease term	15 years

Leases - Schedule of Maturities

Leases - Schedule of Maturities of Operating Lease Liabilities (Details) $ in Thousands	Dec. 31, 2020USD ($)
Leases [Abstract]
2021	$ 23,030
2022	22,560
2023	21,168
2024	20,759
2025	21,300
Thereafter	57,458
Total future minimum payments	166,275
Less: Imputed interest	(36,192)
Present value of operating lease liabilities	$ 130,083

Leases - Schedule of Estimated

Leases - Schedule of Estimated Undiscounted Lease Payments for Leases (Details) $ in Thousands	Dec. 31, 2020USD ($)
Leases [Abstract]
2021	$ 2,271
2022	3,551
2023	3,364
2024	3,445
2025	3,545
Thereafter	21,065
Total undiscounted lease payments expected to be capitalized	$ 37,241

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Lease Payments Under Noncancelable Operating Leases (Details) $ in Thousands	Dec. 31, 2019USD ($)
Leases [Abstract]
2020	$ 20,530
2021	22,059
2022	19,610
2023	18,307
2024	17,957
Thereafter	67,208
Total future minimum payments	$ 165,671

Leases - Schedule of Supplement

Leases - Schedule of Supplemental Cash Flow Information Related to Operating Leases (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Leases [Abstract]
Operating cash flows used for operating leases	$ 21,381
Operating lease assets obtained in exchange for operating lease liabilities	$ 23,853

Leases - Schedule of Weighted A

Leases - Schedule of Weighted Average Remaining Lease Term and Discount Rate For Operating Leases (Details)	Dec. 31, 2020
Leases [Abstract]
Weighted average remaining lease term	7 years 3 months 18 days
Weighted average discount rate	6.60%

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Future Minimum Payments Under Noncancelable Purchase Commitments (Details) $ in Thousands	Dec. 31, 2020USD ($)
Commitments And Contingencies Disclosure [Abstract]
2021	$ 2,569
2022	2,420
2023	573
Total future minimum payments	$ 5,562

Commitments and Contingencies_2

Commitments and Contingencies - Additional Information (Details) $ in Millions	1 Months Ended
	Jan. 31, 2018USD ($)Installment	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Other Commitments [Line Items]
Outstanding liability		$ 0.5	$ 0.9
Other Accrued and Current Liabilities
Other Commitments [Line Items]
Outstanding liability			0.5
Other Noncurrent Liabilities
Other Commitments [Line Items]
Outstanding liability			$ 0.4
Selling, General and Administrative
Other Commitments [Line Items]
Estimated fair value of grant expense	$ 1.7
Fair value of grant, discount rate	10.00%
Endowment Agreement
Other Commitments [Line Items]
Donation fund	$ 2
Annual installment payment of donation fund	$ 0.5
Number of annual installments | Installment	4

Income Taxes - Components of Co

Income Taxes - Components of Company's Tax Provision (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
State	$ 101	$ 199	$ 99
Total current tax expense	101	199	99
Deferred:
Total provision for income taxes	$ 101	$ 199	$ 99

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Company's Effective Tax Rate To Statutory Federal Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Tax at federal statutory rate	$ (43,259)	$ (20,272)	$ (15,890)
State taxes, net of federal effect	(10,315)	(5,170)	(4,280)
Non-deductible items	841	1,429	537
Valuation allowance	52,834	24,212	19,732
Total provision for income taxes	$ 101	$ 199	$ 99

Income Taxes - Components of De

Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 129,333	$ 78,875
Fixed assets and intangibles	3,794	2,747
Accruals and reserves	9,155	8,430
Operating lease liabilities	35,267
Gross deferred tax assets	177,549	90,052
Less: valuation allowance	(143,214)	(88,450)
Total deferred tax assets	34,335	1,602
Deferred tax liabilities:
Operating lease right-of-use assets	(32,028)
Other	(2,307)	(1,602)
Gross deferred tax liabilities	$ (34,335)	$ (1,602)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Change in valuation allowance	$ 54,800,000	$ 22,800,000
Uncertain tax positions	0	0
Tax penalties and interest expense	0	0	$ 0
Tax penalties and interest accrued	0	0	0
Federal Tax
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	$ 485,100,000	$ 302,200,000
Operating loss carryforward expiration year	2032	2032
Net operating loss not available to offset future taxable income		$ 3,300,000
Federal Tax | Expiration in 2032
Operating Loss Carryforwards [Line Items]
Operating loss carryforward			168,200,000
Federal Tax | No expiration
Operating Loss Carryforwards [Line Items]
Operating loss carryforward			$ 316,900,000
State Tax
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	$ 458,900,000	$ 260,700,000
Operating loss carryforward expiration year	2032	2032
Net operating loss not available to offset future taxable income		$ 2,100,000

Net Loss Per Share Attributab_3

Net Loss Per Share Attributable to Common Stockholders - Schedule of Reconciliation of Numerator and Denominator Used in Calculation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator
Net loss attributable to common stockholders	$ (175,832)	$ (101,784)	$ (84,687)
Denominator
Weighted-average common shares outstanding used to calculate net loss per share attributable to common stockholders, basic and diluted	87,587,409	47,478,544	8,365,344
Net loss per share attributable to common stockholders, basic and diluted	$ (2.01)	$ (2.14)	$ (10.12)

Net Loss Per Share Attributab_4

Net Loss Per Share Attributable to Common Stockholders - Schedule of Anti-dilutive Securities Excluded from Computation of Diluted Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	20,728,286	9,961,573	63,058,896
Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share			36,862,298
Redeemable Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share			16,410,256
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	5,809,376	9,171,756	9,672,102
RSUs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	5,103,727	789,817
Warrants | Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share			103,563
Employee Stock Purchase Plan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	109,729
Convertible Senior Notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	9,705,454
Common Stock | Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share			10,677

Retirement Plan - Additional In

Retirement Plan - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020USD ($)
Defined Contribution Plan Disclosure [Line Items]
Percentage of employee vested contributions	25.00%
Maximum
Defined Contribution Plan Disclosure [Line Items]
Employer discretionary contribution amount	$ 1,000

Related Parties - Additional In

Related Parties - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
RealReal Foundation
Related Party Transaction [Line Items]
Donation to related party	$ 3.2