TuSimple (TSPH) 10-Q 4 Nov 21 2021 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Sep. 30, 2021	Oct. 31, 2021
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	001-40326
Entity Registrant Name	TuSimple Holdings Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	86-2341575
Entity Address, Address Line One	9191 Towne Centre Drive
Entity Address, Address Line Two	Suite 600
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92122
City Area Code	619
Local Phone Number	916-3144
Title of 12(b) Security	Class A Common Stock, par value $0.0001 per share
Trading Symbol	TSP
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	true
Entity Small Business	false
Entity Ex Transition Period	false
Entity Shell Company	false
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001823593
Current Fiscal Year End Date	--12-31
Common Class A
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		189,026,565
Common Class B
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		24,000,000

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 1,412,128	$ 310,815
Accounts receivable, net	1,704	1,144
Prepaid expenses and other current assets	15,900	3,816
Amounts due from related parties	0	3,708
Total current assets	1,429,732	319,483
Property and equipment, net	29,419	22,116
Other assets	5,875	4,986
Total assets	1,465,026	346,585
Current liabilities:
Accounts payable	4,416	4,542
Amounts due to related parties	0	4,360
Amounts due to joint development partners	6,997	1,355
Accrued expenses and other current liabilities	33,106	22,961
Short-term debt	813	4,623
Warrants liability	0	42,452
Capital lease liabilities, current	796	805
Total current liabilities	46,128	81,098
Capital lease liabilities, noncurrent	3,045	3,767
Other liabilities	5,814	2,402
Total liabilities	54,987	87,267
Commitments and contingencies (Note 4)
Redeemable convertible preferred stock, $0.0001 par value; 138,102,770 and zero shares authorized as of December 31, 2020 and September 30, 2021; 102,074,703 and zero shares issued and outstanding as of December 31, 2020 and September 30, 2021, respectively; aggregate liquidation preference of $598,842 and $0 as of December 31, 2020 and September 30, 2021, respectively	0	664,791
Stockholders' equity (deficit):
Common stock, $0.0001 par value; 361,897,230 and 4,876,000,000 Class A shares authorized as of December 31, 2020 and September 30, 2021; 60,543,337 and 188,994,830 shares issued and outstanding as of December 31, 2020 and September 30, 2021, respectively; zero and 24,000,000 Class B shares authorized as of December 31, 2020 and September 30, 2021; zero and 24,000,000 shares issued and outstanding as of December 31, 2020 and September 30, 2021, respectively	21	6
Additional paid-in-capital	2,432,613	0
Accumulated other comprehensive loss	(238)	(301)
Accumulated deficit	(1,022,357)	(405,178)
Total stockholders’ equity (deficit)	1,410,039	(405,473)
Total liabilities, redeemable convertible preferred stock and stockholders’ equity (deficit)	$ 1,465,026	$ 346,585

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Redeemable convertible preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Redeemable convertible preferred stock, shares authorized (in shares)	0	138,102,770
Redeemable convertible preferred stock, shares issued (in shares)	0	102,074,703
Redeemable convertible preferred stock, shares outstanding (in shares)	0	102,074,703
Redeemable convertible preferred stock, aggregate liquidation preference	$ 0	$ 598,842
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common Class A
Common stock, shares authorized (in shares)	4,876,000,000	361,897,230
Common stock, shares outstanding (in shares)	188,994,830	60,543,337
Common stock, shares issued (in shares)	188,994,830	60,543,337
Common Class B
Common stock, shares authorized (in shares)	24,000,000	0
Common stock, shares outstanding (in shares)	24,000,000	0
Common stock, shares issued (in shares)	24,000,000	0

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Revenue	$ 1,785	$ 584	$ 4,211	$ 1,106
Costs and expenses:
Cost of revenue	3,487	1,330	8,715	2,958
Research and development	84,506	60,041	204,774	100,202
Sales and marketing	910	459	2,629	1,139
General and administrative	28,831	15,271	83,537	27,204
Total costs and expenses	117,734	77,101	299,655	131,503
Loss from operations	(115,949)	(76,517)	(295,444)	(130,397)
Change in fair value of related party convertible loan	0	(11,849)	0	(11,849)
Change in fair value of warrants liability	0	(970)	(326,900)	(970)
Gain on loan extinguishment	0	0	4,183	0
Other income (expense), net	459	(116)	982	(81)
Loss before provision for income taxes	(115,490)	(89,452)	(617,179)	(143,297)
Provision for income taxes	0	0	0	0
Net loss	(115,490)	(89,452)	(617,179)	(143,297)
Accretion of redeemable convertible preferred stock	0	11,943	4,135	11,943
Net loss attributable to common stockholders, basic	(115,490)	(101,395)	(621,314)	(155,240)
Net loss attributable to common stockholders, diluted	$ (115,490)	$ (101,395)	$ (621,314)	$ (155,240)
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.54)	$ (1.73)	$ (4.08)	$ (2.70)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.54)	$ (1.73)	$ (4.08)	$ (2.70)
Weighted-average shares used in computing net loss per share, basic (in shares)	212,802,379	58,606,231	152,469,098	57,584,574
Weighted-average shares used in computing net loss per share, diluted (in shares)	212,802,379	58,606,231	152,469,098	57,584,574

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net loss	$ (115,490)	$ (89,452)	$ (617,179)	$ (143,297)
Other comprehensive income (loss):
Foreign currency translation adjustment	(73)	285	63	475
Comprehensive loss	$ (115,563)	$ (89,167)	$ (617,116)	$ (142,822)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Initial Public Offering	Private Placement	Redeemable convertible preferred stock	Redeemable convertible preferred stockInitial Public Offering	Series D-1 Redeemable Convertible Preferred Shares	Series E Redeemable Convertible Preferred Stock	Series E-2 Redeemable Convertible Preferred Stock	Common Stock	Common StockInitial Public Offering	Common StockPrivate Placement	Additional Paid-in Capital	Additional Paid-in CapitalInitial Public Offering	Additional Paid-in CapitalPrivate Placement	Accumulated Other Comprehensive Loss	Accumulated Deficit	Total TuSimple Holdings Inc. Stockholders’ Deficit	Noncontrolling Interests
Beginning Balance (in shares) at Dec. 31, 2019				74,939,388
Beginning Balance at Dec. 31, 2019				$ 293,736
Ending Balance (in shares) at Mar. 31, 2020				74,939,388
Ending Balance at Mar. 31, 2020				$ 293,736
Beginning Balance (in shares) at Dec. 31, 2019									56,516,425
Beginning Balance at Dec. 31, 2019	$ (219,414)								$ 6			$ 0			$ (658)	$ (218,718)	$ (219,370)	$ (44)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock from exercise of options (in shares)									2,125,000
Stock-based compensation	1,227											1,227					1,227
Acquisition of noncontrolling interest in subsidiary															(44)		(44)	44
Foreign currency translation adjustment	2														2		2
Net loss	(25,761)															(25,761)	(25,761)
Ending Balance (in shares) at Mar. 31, 2020									58,641,425
Ending Balance at Mar. 31, 2020	(243,946)								$ 6			1,227			(700)	(244,479)	(243,946)	0
Beginning Balance (in shares) at Dec. 31, 2019				74,939,388
Beginning Balance at Dec. 31, 2019				$ 293,736
Ending Balance (in shares) at Sep. 30, 2020				76,788,483
Ending Balance at Sep. 30, 2020				$ 308,736
Beginning Balance (in shares) at Dec. 31, 2019									56,516,425
Beginning Balance at Dec. 31, 2019	(219,414)								$ 6			0			(658)	(218,718)	(219,370)	(44)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation adjustment	475
Ending Balance (in shares) at Sep. 30, 2020									60,542,721
Ending Balance at Sep. 30, 2020	(364,854)								$ 6			0			(227)	(364,633)	(364,854)	0
Beginning Balance (in shares) at Mar. 31, 2020				74,939,388
Beginning Balance at Mar. 31, 2020				$ 293,736
Ending Balance (in shares) at Jun. 30, 2020				74,939,388
Ending Balance at Jun. 30, 2020				$ 293,736
Beginning Balance (in shares) at Mar. 31, 2020									58,641,425
Beginning Balance at Mar. 31, 2020	(243,946)								$ 6			1,227			(700)	(244,479)	(243,946)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	453											453					453
Foreign currency translation adjustment	188														188		188
Net loss	(28,084)															(28,084)	(28,084)
Ending Balance (in shares) at Jun. 30, 2020									58,641,425
Ending Balance at Jun. 30, 2020	(271,389)								$ 6			1,680			(512)	(272,563)	(271,389)	0
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of redeemable convertible preferred stock, net of issuance costs (in shares)						1,849,095
Issuance of redeemable convertible preferred stock, net of issuance costs						$ 3,057
Accretion of redeemable convertible preferred stock to redemption value				$ 11,943
Ending Balance (in shares) at Sep. 30, 2020				76,788,483
Ending Balance at Sep. 30, 2020				$ 308,736
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted ordinary shares (in shares)									1,899,680
Issuance of common stock from exercise of options (in shares)									1,616
Accretion of redeemable convertible preferred stock to redemption value	(11,943)											(9,325)				(2,618)	(11,943)
Stock-based compensation	7,645											7,645					7,645
Foreign currency translation adjustment	285														285		285
Net loss	(89,452)															(89,452)	(89,452)
Ending Balance (in shares) at Sep. 30, 2020									60,542,721
Ending Balance at Sep. 30, 2020	$ (364,854)								$ 6			0			(227)	(364,633)	$ (364,854)	$ 0
Beginning Balance (in shares) at Dec. 31, 2020	102,074,703			102,074,703
Beginning Balance at Dec. 31, 2020	$ 664,791			$ 664,791
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of redeemable convertible preferred stock, net of issuance costs (in shares)							4,650,999
Issuance of redeemable convertible preferred stock, net of issuance costs							$ 61,631
Issuance of redeemable convertible preferred stock from the exercise of warrants (in shares)							9,477,073	4,331,644
Issuance of redeemable convertible preferred stock from the exercise of warrants							$ 379,084	$ 173,275
Accretion of redeemable convertible preferred stock to redemption value				$ 4,135
Ending Balance (in shares) at Mar. 31, 2021				120,534,419
Ending Balance at Mar. 31, 2021				$ 1,282,916
Beginning Balance (in shares) at Dec. 31, 2020									60,543,337
Beginning Balance at Dec. 31, 2020	(405,473)								$ 6			0			(301)	(405,178)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock from exercise of options (in shares)									60,616
Issuance of common stock from exercise of options	1											1
Vesting of early exercised stock options	21											21
Accretion of redeemable convertible preferred stock to redemption value	(4,135)											(4,135)
Stock-based compensation	6,289											6,289
Foreign currency translation adjustment	911														911
Net loss	(385,160)															(385,160)
Ending Balance (in shares) at Mar. 31, 2021									60,603,953
Ending Balance at Mar. 31, 2021	$ (787,546)								$ 6			2,176			610	(790,338)
Beginning Balance (in shares) at Dec. 31, 2020	102,074,703			102,074,703
Beginning Balance at Dec. 31, 2020	$ 664,791			$ 664,791
Ending Balance (in shares) at Sep. 30, 2021	0			0	0
Ending Balance at Sep. 30, 2021	$ 0			$ 0
Beginning Balance (in shares) at Dec. 31, 2020									60,543,337
Beginning Balance at Dec. 31, 2020	(405,473)								$ 6			0			(301)	(405,178)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation adjustment	63
Ending Balance (in shares) at Sep. 30, 2021									212,994,830
Ending Balance at Sep. 30, 2021	1,410,039								$ 21			2,432,613			(238)	(1,022,357)
Beginning Balance (in shares) at Mar. 31, 2021				120,534,419
Beginning Balance at Mar. 31, 2021				$ 1,282,916
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of redeemable convertible preferred stock in connection with initial public offering (in shares)					(120,534,419)
Conversion of redeemable convertible preferred stock in connection with initial public offering					$ (1,282,916)
Ending Balance (in shares) at Jun. 30, 2021				0
Ending Balance at Jun. 30, 2021				$ 0
Beginning Balance (in shares) at Mar. 31, 2021									60,603,953
Beginning Balance at Mar. 31, 2021	(787,546)								$ 6			2,176			610	(790,338)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of early exercised stock options	21											21
Conversion of convertible common stock in connection with initial public offering (in shares)										120,534,419
Conversion of convertible common stock in connection with initial public offering		$ 1,282,916								$ 12			$ 1,282,904
Issuance of common stock (in shares)										27,027,027	874,999
Issuance of common stock		$ 1,027,374	$ 35,000							$ 3			$ 1,027,371	$ 35,000
Stock-based compensation	52,509											52,509
Foreign currency translation adjustment	(775)														(775)
Net loss	(116,529)															(116,529)
Ending Balance (in shares) at Jun. 30, 2021									209,040,398
Ending Balance at Jun. 30, 2021	$ 1,492,970								$ 21			2,399,981			(165)	(906,867)
Ending Balance (in shares) at Sep. 30, 2021	0			0	0
Ending Balance at Sep. 30, 2021	$ 0			$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock from exercise of options (in shares)									183,648
Issuance of common stock from exercise of options	529											529
Issuance of common stock related to release of RSU and SVAs (in shares)									3,770,784
Vesting of early exercised stock options	21											21
Stock-based compensation	32,082											32,082
Foreign currency translation adjustment	(73)														(73)
Net loss	(115,490)															(115,490)
Ending Balance (in shares) at Sep. 30, 2021									212,994,830
Ending Balance at Sep. 30, 2021	$ 1,410,039								$ 21			$ 2,432,613			$ (238)	$ (1,022,357)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net loss	$ (617,179)	$ (143,297)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	90,880	9,325
Accretion of asset retirement obligations	0	27
Depreciation and amortization	6,768	5,611
Loss on disposal of property and equipment	0	127
Non-cash research and development expense	0	32,325
Change in fair value of warrants liability	326,900	970
Gain on loan extinguishment	(4,183)	0
Change in fair value of related party convertible loan	0	11,849
Changes in operating assets and liabilities:
Accounts receivable	(560)	(298)
Prepaid expenses and other current assets	(12,114)	1,251
Other assets	(659)	(339)
Accounts payable	(313)	1,359
Amounts due to/from related parties	0	(274)
Amounts due to joint development partners	5,642	0
Accrued expenses and other current liabilities	16,488	15,317
Other liabilities	1,965	1,263
Net cash used in operating activities	(186,365)	(64,784)
Cash flows from investing activities:
Purchases of property and equipment	(12,218)	(2,881)
Purchases of intangible assets	(302)	(207)
Proceeds from disposal of property and equipment	100	178
Net cash used in investing activities	(12,420)	(2,910)
Cash flows from financing activities:
Proceeds from issuance of redeemable convertible preferred stock, net of offering costs	54,693	3,057
Proceeds from exercise of warrants for redeemable convertible preferred stock	183,007	0
Proceeds from issuance of related party convertible loan	0	50,000
Proceeds from issuance of warrants	0	11,943
Proceeds from early exercised stock options	782	0
Proceeds from issuance of common stock upon initial public offering, net of offering costs	1,030,965	0
Proceeds from issuance of common stock related to private placement	35,000	0
Proceeds from related party loan	0	5,000
Proceeds from loans	0	4,134
Return of guarantee deposit on related party loan	3,715	0
Principal payments on related party loan	(4,398)	0
Payment of third-party costs in connection with initial public offering	(2,812)	0
Principal payments on capital lease obligations	(586)	(528)
Principal payments on other liabilities	(353)	(38)
Net cash provided by financing activities	1,300,013	73,568
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	55	(324)
Net increase in cash, cash equivalents, and restricted cash	1,101,283	5,550
Cash, cash equivalents, and restricted cash - beginning of period	312,351	64,110
Cash, cash equivalents, and restricted cash - end of period	1,413,634	69,660
Reconciliation of cash, cash equivalents, and restricted cash to the condensed consolidated balance sheets:
Cash and cash equivalents	1,412,128	68,910
Restricted cash included in prepaid expenses and other current assets	1,506	750
Total cash and cash equivalents, and restricted cash	1,413,634	69,660
Supplemental disclosure of cash flow information:
Cash paid for interest	575	850
Supplemental schedule of non-cash investing and financing activities:
Acquisitions of property and equipment included in current liabilities	1,987	1,526
Accretion of redeemable convertible preferred stock	4,135	11,943
Vesting of early exercised stock options	63	0
Exercise of liability-classified warrants	369,352	0
Conversion of redeemable convertible preferred stock to common stock upon initial public offering	1,282,916	0
Cashless exercise of stock options for common stock	0	975
Issuance costs incurred in connection with initial public offering included in current liabilities	$ 779	$ 0

Description of Business and Sum

Description of Business and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Summary of Significant Accounting Policies	Description of Business and Summary of Significant Accounting Policies Description of Business TuSimple Holdings Inc. (“TuSimple” or the “Company”) is principally engaged in the operation and development of autonomous trucks and an autonomous freight network (“AFN”). The Company is headquartered in San Diego, California. TuSimple was originally incorporated as Tusimple (Cayman) Limited, a limited liability company in the Cayman Islands, on October 25, 2016. In February 2021, the Company deregistered as a Cayman Islands exempted company and continued and domesticated as a corporation incorporated under the laws of the State of Delaware (the “Domestication”). The business, assets and liabilities of the Company and its subsidiaries on a consolidated basis, as well as its principal locations and fiscal year, were the same immediately after the Domestication as they were immediately prior to the Domestication. In addition, the directors and executive officers of the Company immediately after the Domestication were the same individuals who were directors and executive officers, respectively, of the Company immediately prior to the Domestication. Initial Public Offering and Private Placement On April 19, 2021, the Company closed its initial public offering (“IPO”) and concurrent private placement, in which it issued and sold 27,027,027 shares and 874,999 shares, respectively, of its authorized Class A common stock at $40.00 per share, resulting in net proceeds of $1.0 billion after deducting underwriting discounts and commissions of $50.1 million and offering costs. Upon closing of the IPO, (i) the Company filed an amended and restated certificate of incorporation, which authorized 4,876,000,000 shares of Class A common stock and reclassified all outstanding common stock into Class A common stock, authorized 24,000,000 shares of Class B common stock, which are not publicly traded, and authorized 100,000,000 shares of undesignated preferred stock, (ii) Xiaodi Hou and Mo Chen (the “Founders”) each exchanged 12,000,000 shares of their newly designated Class A common stock for an equivalent number of shares of Class B common stock, and (iii) all shares of the Company’s outstanding redeemable convertible preferred stock automatically converted into 120,534,419 shares of Class A common stock. The rights of the holders of Class A common stock and Class B common stock are identical, except with respect to voting, conversion, and transfer rights. The holders of Class A common stock are entitled to one vote per share and the holders of Class B common stock are entitled to 10 votes per share. Additionally, each share of Class B common stock will automatically convert, on a one-for-one basis, into shares of Class A common stock on the earliest of (i) the date specified by a vote of the holders of Class B common stock representing 75% of the outstanding shares of Class B common stock, (ii) the date that is between 90 days and 270 days, as determined by the board of directors, after the death or incapacitation of the last Founder to die or become incapacitated, or (iii) the date that is between 61 days and 180 days, as determined by the board of directors, after the date on which the number of outstanding shares of Class B common stock held by the Founders (or their permitted affiliates) is less than 12,000,000 shares. Upon the closing of the IPO, the Company recognized $42.6 million of stock-based compensation expense related to stock options, restricted stock units (“RSUs”), and share value awards (“SVAs”), for which the time-based vesting conditions had been satisfied or partially satisfied and the performance-based conditions were satisfied upon the closing of the IPO. Additionally, the Company recorded $4.3 million within operating expenses to former employees in connection with post-employment agreements for which payment was contingent upon the occurrence of an IPO or Sale Event (as such terms are defined in the post-employment agreements). Basis of Presentation and Consolidation The accompanying unaudited condensed consolidated financial statements (“Financial Statements”) have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. The condensed consolidated financial statements include the accounts of the Company and its consolidated subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. These Financial Statements should be read in conjunction with the audited consolidated financial statements and notes included in the Company’s final prospectus filed with the SEC pursuant to Rule 424(b) under the Securities Act of 1933, as amended, on April 16, 2021 (the “Prospectus”). The condensed consolidated balance sheet as of December 31, 2020, was derived from the audited consolidated financial statements as of that date, but does not include all disclosures required by GAAP. In management’s opinion, the accompanying Financial Statements reflect all normal recurring adjustments necessary for their fair presentation. Other than described below, there have been no changes to the Company’s significant accounting policies described in the Prospectus that have had a material impact on the Company’s Financial Statements. Stock-Based Compensation The Company accounts for stock-based compensation expense in accordance with the fair value recognition and measurement provisions of GAAP, which requires compensation cost for the grant-date fair value of stock-based awards to be recognized over the requisite service period. The Company determines the fair value of stock-based awards granted or modified on the grant date (or modification date, if applicable) at fair value, using appropriate valuation techniques. Time-Based Service Awards For stock-based awards with time-based vesting conditions only, generally being RSUs and stock options, stock-based compensation is recognized straight-line over the requisite service period, which is generally four years. The fair value of RSUs is measured on the grant date based on the closing fair market value of the Company's Class A common stock. The fair value of stock option awards is estimated on the grant date using the Black-Scholes option-pricing model. The Black-Scholes option-pricing model requires the input of highly subjective assumptions, including the fair value of the underlying common stock, the expected stock price volatility over the term of the award, actual and projected employee stock option exercise behaviors, the risk-free interest rate for the expected term of the award and expected dividends. The Company accounts for forfeitures as they occur instead of estimating the number of awards expected to be forfeited. Performance-Based Awards The Company has granted RSUs, SVAs, and stock options that vest only upon the satisfaction of both time-based service and performance-based conditions. The time-based service condition for these awards generally is satisfied over four years The performance-based conditions, other than with respect to the CEO Performance Award discussed in Note 6. Stock Based Compensation, are satisfied upon the occurrence of a qualifying event, defined as the earlier of (i) the closing of certain specific liquidation or change in control transactions, or (ii) an IPO. The Company records stock-based compensation expense for performance-based equity awards such as RSUs, SVAs, and stock options on an accelerated attribution method over the requisite service period, which is generally four years, and only if performance-based conditions are considered probable to be satisfied. Upon completion of the IPO, the Company recorded a cumulative one-time stock-based compensation expense determined using the grant-date fair values. Stock-based compensation related to remaining time-based service after the qualifying event is recorded over the remaining requisite service period. For performance-based RSUs and SVAs, the Company determines the grant-date fair value as the fair value of the Company’s common stock on the grant date. For performance-based awards with a vesting schedule based entirely on the attainment of both performance and market conditions, stock-based compensation expense associated with each tranche is recognized over the longer of (i) the expected achievement period for the operational milestones for such tranche and (ii) the expected achievement period for the related market capitalization milestone determined on the grant date, beginning at the point in time when the relevant operational milestones are considered probable of being met. If such operational milestones become probable any time after the grant date, the Company will recognize a cumulative catch-up expense from the grant date to that point in time. If the related market capitalization milestone is achieved earlier than its expected achievement period and the achievement of the related operational milestones, then the stock-based compensation expense will be recognized over the expected achievement period for the operational milestones, which may accelerate the rate at which such expense is recognized. The fair value of such awards is estimated on the grant date using Monte Carlo simulations. Refer to Note 6. Stock Based Compensation for further information. Employee Stock Purchase Plan ("ESPP") The Company recognizes stock-based expense related to shares issued pursuant to the ESPP on a straight-line basis over the offering period. The ESPP provides for six-month offering periods. The ESPP allows eligible employees to purchase shares of Class A common stock at a 15% discount on the lower of our stock price on either (i) the offering period beginning date or (ii) the purchase date. No employee may purchase shares under the ESPP at a rate in excess of $25,000 worth of Class A common stock based on the fair market value per share of Class A common stock at the beginning of an offering for each calendar year such purchase right is outstanding or 1,500 shares. The Company estimates the fair value of shares to be issued under the ESPP based on a combination of options valued using the Black-Scholes option-pricing model. Volatility is determined over an expected term of six months based on the Company's historical volatility. The expected term is estimated based on the contractual term. Reclassifications Certain prior period balances have been reclassified to conform to the current period presentation in the condensed consolidated financial statements and the accompanying notes. Restricted cash has been reclassified to prepaid expenses and other current assets and accrued expenses incurred under joint development agreements have been reclassified to be presented separately from amounts due to related parties. Recently Adopted Accounting Pronouncements In August 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2018-15, Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that Is a Service Contract , which aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). The Company adopted the guidance as of January 1, 2021 with no material impact to the Financial Statements. In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes . This ASU simplifies the accounting for income taxes by eliminating some exceptions to the general approach in ASC 740, Income Taxes , for recognizing deferred taxes for investments, performing intraperiod allocation and calculating income taxes in interim periods. The Company adopted ASU 2019-12 in the first quarter of 2021 and the adoption had no material impact to the Financial Statements. Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases as modified by subsequently issued ASUs 2018-01, 2018-10 and 2018-11. The core principle of the ASU improves transparency and comparability related to the accounting and reporting of leasing arrangements, including balance sheet recognition for assets and liabilities associated with rights and obligations created by leases with terms greater than twelve months, among other changes. For the Company, the effective date of these ASUs is for fiscal years beginning after December 15, 2021 and early adoption is permitted. The Company has elected not to early adopt these ASUs and plans to elect the modified retrospective application by recording a cumulative effect adjustment to the opening balance of retained earnings in the period of adoption. In addition, the Company expects to avail itself of the package of practical expedients allowing the Company to not reassess (i) whether any expired or existing contracts are or contain leases, (ii) the lease classification for any expired or existing leases, and (iii) the initial direct costs for any existing leases. The Company anticipates recognizing material right-of-use assets and related liabilities upon adoption.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The following table presents the Company’s assets and liabilities that are measured at fair value on a recurring basis and indicates the fair value hierarchy of the valuation (in thousands): As of December 31, 2020 Total Level 1 Level 2 Level 3 Assets: Cash equivalents: Certificates of deposit $ 279,279 $ 279,279 $ — $ — Total $ 279,279 $ 279,279 $ — $ — Liabilities: Warrants liability $ 42,452 $ — $ — $ 42,452 Total $ 42,452 $ — $ — $ 42,452 As of September 30, 2021 Total Level 1 Level 2 Level 3 Assets: Cash equivalents: Certificates of deposit $ — $ — $ — $ — Money market funds 1,147,989 1,147,989 — — Total $ 1,147,989 $ 1,147,989 $ — $ — Warrants Liability As of December 31, 2020, the fair value of the warrants liability was estimated using the Black-Scholes option-pricing model. The fair value of the underlying redeemable convertible preferred stock used within the Black-Scholes option-pricing model was estimated using a hybrid between a probability-weighted expected return method (“PWERM”) and option pricing model (“OPM”), estimating the probability-weighted value across multiple scenarios, while using an OPM to estimate the allocation of value within one or more of these scenarios. Discrete future outcomes considered under the PWERM include an IPO of the Company’s common stock, as well as continued operation as a private company. The significant unobservable inputs into the valuation model include the timing and probability of occurrence of these discrete future outcomes and a discount for the lack of marketability of the redeemable convertible preferred stock. In February and March 2021, Traton SE (“Traton”) and Navistar, Inc. (“Navistar”) exercised warrants to purchase 4,331,644 and 9,477,073 shares of Series E-2 and Series E redeemable convertible preferred stock at an exercise price of $11.31 and $14.14, resulting in proceeds of $49.0 million and $134.0 million, respectively. Immediately prior to their exercise, the fair value of the warrants liability was remeasured using the Black-Scholes model. The warrants exercised by Traton represented only a portion of their total and the unexercised warrants expired as of the exercise date. As of September 30, 2021, there were no warrants outstanding. Refer to Note 5. Redeemable Convertible Preferred Stock, Preferred Stock Warrants, and Stockholders’ Equity for further information. The Company used the following assumptions in the model: As of December 31, February 26, 2021 March 19, 2021 Discount for lack of marketability 9.00% - 30.00% — — Fair value of underlying securities $14.14 $40.00 $40.00 Expected volatility 53.90% - 76.90% 62.95% 60.85% Expected term (in years) 0.33 - 1.91 1.76 0.79 Risk-free interest rate 0.10% - 0.13% 0.14% 0.08% The following table sets forth a summary of the changes in the estimated fair value of the Company’s warrants liability (in thousands): Balance as of December 31, 2020 $ 42,452 Change in fair value of warrants 326,900 Exercises during the period (369,352) Balance as of September 30, 2021 $ —

Balance Sheet Components

Balance Sheet Components	9 Months Ended
	Sep. 30, 2021
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	Balance Sheet Components Property and Equipment, Net Property and equipment, net as of December 31, 2020 and September 30, 2021, was as follows (in thousands): As of December 31, September 30, Electronic equipment $ 11,429 $ 12,396 Office and other equipment 6,152 8,975 Vehicles 12,775 16,369 Leasehold improvements 7,340 10,542 Construction in progress 225 2,985 Property and equipment, gross 37,921 51,267 Accumulated depreciation and amortization (15,805) (21,848) Property and equipment, net $ 22,116 $ 29,419 Depreciation and amortization expense was $1.8 million and $5.6 million for the three and nine months ended September 30, 2020, respectively, and $2.3 million and $6.7 million for the three and nine months ended September 30, 2021, respectively. As of December 31, 2020 and September 30, 2021, property and equipment financed under capital leases was $4.6 million and $4.2 million, net of accumulated amortization of $1.8 million and $2.3 million, respectively. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities as of December 31, 2020 and September 30, 2021 were as follows (in thousands): As of December 31, September 30, Accrued payroll $ 11,941 $ 24,604 Accrued professional fees 7,865 3,254 Other 3,155 5,248 Accrued expenses and other current liabilities $ 22,961 $ 33,106

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Lease Commitments The Company has entered into various noncancelable operating leases for its facilities with various expiry dates through 2033. Future minimum lease payments for non-cancelable operating and capital leases as of September 30, 2021 are as follows (in thousands): Year Ending December 31, Operating Leases Capital Leases Remainder of 2021 $ 1,746 $ 341 2022 6,950 1,253 2023 7,136 978 2024 4,870 963 2025 3,418 1,761 Thereafter 21,193 — Total minimum lease payments $ 45,313 5,296 Amount representing interest (1,455) Present value of minimum lease payments $ 3,841 Rental expenses amounted to $1.5 million and $3.9 million for the three and nine months ended September 30, 2020, respectively, and $1.6 million and $4.3 million for the three and nine months ended September 30, 2021, respectively. Joint Development Agreement In April 2020, the Company entered into a Development Agreement (“DA”) with Scania relating to a hub-to-hub pilot program using Scania vehicles and the Company’s autonomous technology in northern Europe. Under the DA, each party will fund its own costs related to the program. There are no reimbursements paid between the parties and there are no spending floors included within the DA. Upon successful completion of the development activities, the parties intend to set up a long-term cooperation agreement covering development, maintenance, operation, and sales of self-driving systems on a global scale. The terms and conditions of such arrangement will be negotiated by the parties and included in a separate agreement. In July 2020, the Company entered into a Joint Development Agreement (“JDA”) with Navistar, Inc., under which the parties will work collaboratively to develop purpose-built L4 autonomous semi-trucks for the North American market. Under the JDA, the parties grant each other rights to their background intellectual property to permit them to conduct research and development activities. Pursuant to the JDA, the Company agrees to reimburse Navistar up to $10.0 million for research and development expenses incurred. Payment of reimbursements is deferred to align with the achievement of certain milestones and reimbursements due are recorded within accrued expenses in the Company’s condensed consolidated balance sheets. All reimbursements are expected to be paid within 12 months of the Company incurring the obligation. Upon successful completion of the development activities under the JDA, the parties will enter into good faith negotiations for a production license agreement. Products developed will be jointly commercialized by the parties. As of September 30, 2021, expenses incurred to-date by Navistar for reimbursement under the JDA are $10.0 million. Payroll Protection Program (“PPP”) Loan In April 2020, the Company received loan proceeds in the amount of $4.1 million under the Small Business Administration Paycheck Protection Program established under Section 1102 of the Coronavirus Aid, Relief and Economic Security (“CARES”) Act. In October 2020, the Company applied for forgiveness of the PPP Loan and corresponding accrued interest, which was approved by the SBA in June 2021. Post-Employment Agreements The Company has entered into post-employment agreements with former employees under which the Company is required to pay additional compensation upon the occurrence of an IPO or Sale Event (as such terms are defined in the post-employment agreements). Since the Company’s IPO, $4.3 million has been paid to said former employees and recorded within operating expenses as of September 30, 2021 pursuant to such post-employment agreements. Litigation and Legal Proceedings The Company is not currently a party to any pending material litigation or other legal proceeding or claims.

Redeemable Convertible Preferre

Redeemable Convertible Preferred Stock, Preferred Stock Warrants, and Stockholders’ Equity	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Redeemable Convertible Preferred Stock, Preferred Stock Warrants, and Stockholders’ Equity	Redeemable Convertible Preferred Stock, Preferred Stock Warrants, and Stockholders’ Equity Redeemable Convertible Preferred Stock In January 2021, the Company issued 4,650,999 shares of Series E redeemable convertible preferred stock at $14.14 per share for aggregate proceeds of $61.6 million, net of issuance costs of $4.1 million. The shares of Series E redeemable convertible preferred stock were accreted to redemption value immediately upon issuance and $4.1 million of accretion was recorded within additional paid-in capital within the condensed consolidated statements of redeemable convertible preferred stock and stockholders’ equity (deficit). In February 2021, Traton exercised warrants to purchase 4,331,644 shares of Series E-2 redeemable convertible preferred stock at an exercise price of $11.31 per share, resulting in aggregate proceeds of $49.0 million. In March 2021, Navistar exercised warrants to purchase 9,477,073 shares of Series E redeemable convertible preferred stock at an exercise price of $14.14 per share, resulting in proceeds of $134.0 million.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement, Noncash Expense [Abstract]
Stock-Based Compensation	Stock-Based Compensation 2017 Share Plan In April 2017, the Company adopted the 2017 Share Plan (the "2017 Plan") under which employees, directors, and consultants could be granted various forms of equity incentive compensation at the discretion of the board of directors, including stock options, restricted shares, RSUs, and SVAs. Stock options granted under the 2017 Plan have a contractual term of ten years and have varying vesting terms, but generally vest over a requisite service period of four years. The exercise price of the stock options granted may not be less than the par value of the common stock on the grant date for non-U.S. tax residents and may not be less than the fair market value of the common stock on the grant date for U.S. tax residents. Certain share options contain a performance condition and are only exercisable subject to the grantee's continuous service and the completion of an IPO. Options which contain a performance condition and for which the service condition has been satisfied are forfeited should employment terminate before the Company’s IPO. In March 2021, the Company’s board of directors approved an amendment to the 2017 Plan to increase the number of shares of common stock reserved for issuance by 2,300,000 shares, for a total of 24,267,694 shares reserved. The 2017 Plan was terminated in connection with the Company’s IPO in April 2021, and the Company will not grant any additional awards under the 2017 Plan. However, the 2017 Plan will continue to govern the terms and conditions of the outstanding awards previously granted under the 2017 Plan. 2021 Equity Incentive Plan In March 2021, the board of directors adopted the 2021 Equity Incentive Plan (the "2021 Plan"), which became effective upon its approval by the board of directors, but for which no awards were eligible to be granted prior to the Company’s IPO in April 2021. The 2021 Plan provides for the grant of stock options, stock appreciation rights (“SARs”), restricted stock, and RSUs to the Company’s employees, directors, and consultants. The number of shares of the Company’s Class A common stock reserved for issuance under the 2021 Plan is 20,134,146 plus up to 19,892,067 shares of Class A common stock subject to awards under the Company’s 2017 Plan. In the event that the aggregate number of shares of Class A common stock that are available for issuance under the 2021 Plan as of the last day of a fiscal year is less than 5% of the Company's fully-diluted capitalization, then for the duration of the 2021 Plan, on the first day of each fiscal year of the Company thereafter, the number of shares of Class A common stock available for issuance under the 2021 Plan will automatically increase by either (i) 2.5% of the Company’s fully-diluted capitalization as of the last day of the immediately preceding fiscal year or (ii) such other amount as determined by the board of directors. 2021 Employee Stock Purchase Plan In March 2021, the board of directors adopted the 2021 Employee Stock Purchase Plan (the "2021 ESPP"), which became effective upon the Company's IPO in April 2021. The 2021 ESPP authorizes the issuance of shares of Class A common stock pursuant to purchase rights granted to employees. A total of 2,013,414 shares of the Company's Class A common stock have been reserved for future issuance under the 2021 ESPP, subject to annual increases authorized by the board of directors; however, the aggregate number of shares of Class A common stock that may be approved for issuance under the 2021 ESPP in any given fiscal year may not exceed 1% of the total number of shares of common stock issued and outstanding on the last business day of the prior fiscal year. The stock-based compensation expense recognized for the 2021 ESPP was $0.2 million during the three and nine months ended September 30, 2021. During the periods ended December 31, 2020 and September 30, 2021, no shares were purchased under the 2021 ESPP. As of September 30, 2021, unrecognized stock-based compensation expense related to the 2021 ESPP was $0.8 million, which is expected to be recognized over a weighted-average period of 0.4 years. The estimated grant-date fair value of the ESPP purchase rights was calculated using the Black-Scholes option-pricing model, based on the following assumptions: Three Months Ended September 30, 2021 Nine Months Ended September 30, 2021 Risk-free interest rate 0.06% 0.06% Expected volatility 97.10% 97.10% Expected term (in years) 0.50 0.50 Fair value of common stock $44.39 $44.39 Stock Options A summary of the stock option activity, including the CEO Performance Award, for the nine months ended September 30, 2021 is as follows (in thousands, except share amounts, per share amounts, and years): Options Outstanding Weighted- Average Exercise Price Weighted- Average Remaining Life (Years) Aggregate Intrinsic Value Outstanding at December 31, 2020 13,295,497 $ 1.29 7.99 $ 97,986 Granted 3,717,968 $ 22.22 Exercised (244,264) $ 3.20 Cancelled/Forfeited (749,962) $ 1.11 Outstanding at September 30, 2021 16,019,239 $ 6.13 7.66 $ 507,736 Vested and exercisable at September 30, 2021 9,514,873 $ 0.55 6.50 $ 348,041 As of September 30, 2021, there was $97.9 million of unrecognized stock-based compensation expense related to unvested stock options, which is expected to be recognized over a weighted-average service period of 3.41 years. Upon the closing of the Company’s IPO, the Company recognized $18.8 million of stock-based compensation expense relating to stock options for which the time-based vesting condition has been satisfied or partially satisfied on that date and for which the performance condition was satisfied upon the occurrence of the IPO. The estimated grant-date fair value of the Company’s stock-based option awards was calculated using the Black-Scholes option-pricing model, based on the following assumptions: Three Months Ended September 30, Nine Months Ended September 30, 2020 2021 2020 2021 Risk-free interest rate 0.21% - 0.31% 0.86% - 0.95% 0.21% - 0.44% 0.33% - 1.04% Expected volatility 60.00% 50.00% 60.00% 50.00% Expected term (in years) 5.00 - 6.06 6.16 5.00 - 6.06 4.05 - 6.22 CEO Performance Award In March 2021, included in the stock options discussed above, the Company granted 1,150,000 stock option awards to its CEO with an exercise price of $14.14 per share and a contractual life of ten years that vest upon the attainment of both operational milestones (performance conditions) and market conditions, assuming continued employment as CEO through the vesting date (the “CEO Performance Award”). The options will vest upon certification by the Board of Directors that all the following milestones have been attained: (i) the average market capitalization of the Company during any consecutive 180-day period is no less than $25.0 billion, (ii) the average number of L4 autonomous semi-trucks operating on the Company’s Autonomous Freight Network in any 90-day period is no less than 1,500, and (iii) the Company’s revenues from its Autonomous Freight Network for any 12-month period exceed $200.0 million. As of September 30, 2021, there was a total of $27.2 million unrecognized stock-based compensation expense for the operational milestones that were considered probable to achieve which will be recognized over a period of 3.17 years. For the three and nine months ended September 30, 2021, the Company recorded stock-based compensation expense of $2.2 million and $5.0 million, respectively, related to the CEO Performance Award. RSUs The following table summarizes the activity related to RSUs for the nine months ended September 30, 2021: RSUs Outstanding Weighted-Average Unvested and outstanding at December 31, 2020 1,100,000 $ 14.14 Granted 4,905,295 $ 50.77 Vested (931,588) $ 19.44 Cancelled (11,928) $ 45.43 Unvested and outstanding at September 30, 2021 5,061,779 $ 48.58 Vested and outstanding at September 30, 2021 142,153 $ 38.19 SVAs The following table summarizes the activity related to SVAs for the nine months ended September 30, 2021: SVAs Outstanding Weighted-Average Unvested and outstanding at December 31, 2020 3,653,146 $ 3.20 Vested (2,981,349) $ 3.08 Cancelled (260,718) $ 5.84 Unvested and outstanding at September 30, 2021 411,079 $ 4.75 Vested and outstanding at September 30, 2021 — $ — As of September 30, 2021, there was $225.4 million of unrecognized stock-based compensation expense related to RSUs and SVAs, which is expected to be recognized over a weighted-average service period of 3.18 years. Upon the Company’s IPO, the Company recognized $23.8 million of stock-based compensation expense relating to RSUs and SVAs for which the time-based vesting condition has been satisfied or partially satisfied on that date and for which the performance condition was satisfied upon the occurrence of the IPO. Early Exercise of Common Stock Options The Company’s board of directors authorized certain stock option holders to exercise unvested options to purchase shares of Class A common stock. Shares of Class A common stock issued upon early exercises of unvested options are not deemed, for accounting purposes, to be issued until those shares vest according to their respective vesting schedules and accordingly, the consideration received for early exercises is initially recorded as a liability and reclassified to common stock and additional paid-in capital as the underlying awards vest. Stock options that are early exercised are subject to repurchase in the event of the optionee’s termination of service, at the original issuance price, until the options are fully vested. As of September 30, 2021, 45,000 shares of Class A common stock were subject to repurchase at a weighted-average price of $4.20 per share. The cash proceeds received for unvested shares of common stock recorded within accrued expenses and other current liabilities in the condensed consolidated balance sheets were $0.2 million as of September 30, 2021. Stock-based Compensation Expense Total stock-based compensation expense was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2020 2021 2020 2021 Research and development $ 402 $ 22,382 $ 547 $ 49,520 Sales and marketing 2 101 2 652 General and administrative 7,241 9,599 8,776 40,708 Total stock-based compensation expense $ 7,645 $ 32,082 $ 9,325 $ 90,880

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Prior to February 2021, the Company was a Cayman Islands incorporated holding company. In February 2021, the Company completed a domestication pursuant to Section 388 of the Delaware General Corporation Law pursuant to which it became a Delaware corporation and was no longer subject to the laws of the Cayman Islands. Following the Domestication, the U.S. federal income tax rate is the applicable statutory rate. The Company’s interim period income tax provision is determined using the estimated annual effective income tax rate applied to year-to-date pretax losses adjusted for the tax effects of legislative changes and other discrete items that relate to the interim period. The estimated annual effective income tax rate is impacted by expected annual earnings, valuation allowances related to current year losses, income tax related to foreign operations, and state tax.

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Stockholders	Net Loss Per Share Attributable to Common Stockholders Basic net loss per share of common stock attributable to common stockholders is calculated by dividing net loss attributable to common stockholders by the weighted-average shares of common stock outstanding for the period. Diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders for all years presented because the effects of potentially dilutive items were antidilutive given the Company’s net loss in each period presented. The following table presents the calculation of basic and diluted net loss per share attributable to common stockholders (in thousands, except share and per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2020 2021 2020 2021 Numerator: Net loss $ (89,452) $ (115,490) $ (143,297) $ (617,179) Less: Accretion of redeemable convertible preferred stock (11,943) — (11,943) (4,135) Net loss attributable to common stockholders, basic and diluted $ (101,395) $ (115,490) $ (155,240) $ (621,314) Denominator: Weighted-average shares used in computing net loss per share, basic and diluted 58,606,231 212,802,379 57,584,574 152,469,098 Net loss per share: Net loss per share attributable to common stockholders, basic and diluted $ (1.73) $ (0.54) $ (2.70) $ (4.08) The following potentially dilutive outstanding shares were excluded from the computation of diluted net loss per share for the periods presented because including them would have had an anti-dilutive effect, or because issuance of such shares is contingent upon the satisfaction of certain conditions which were not satisfied by the end of the period: As of September 30, 2020 2021 Redeemable convertible preferred stock 76,788,483 — Options to purchase common stock 9,760,857 16,019,239 RSUs subject to future vesting — 5,061,779 SVAs subject to future vesting 3,500,815 411,079 Early exercised options subject to future vesting* 1,062,500 45,000 Total 91,112,655 21,537,097 *Refer to Note 6. Stock-Based Compensation for further detail.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2021
Related Party Transactions [Abstract]
Related Party Transactions	Related Party TransactionsAt December 31, 2020, the Company had short-term, unsecured, interest free loans outstanding of approximately $0.6 million due to its executive chairman and approximately $3.7 million due to Jinzhuo Hengbang Technology (Beijing) Co., Ltd. (“Jinzhuo Hengbang”), an affiliated company of Sina Corporation, the ultimate parent company of one of the Company’s investors. Additionally, the Company paid a guarantee deposit of $3.7 million to Sina Corporation in connection with the loans borrowed by the Company from Jinzhuo Hengbang, which was outstanding at December 31, 2020. During the nine months ended September 30, 2021, the Company paid off these loans in their entirety, and received a refund of the guarantee deposit paid to Sina Corporation.

Description of Business and S_2

Description of Business and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business TuSimple Holdings Inc. (“TuSimple” or the “Company”) is principally engaged in the operation and development of autonomous trucks and an autonomous freight network (“AFN”). The Company is headquartered in San Diego, California. TuSimple was originally incorporated as Tusimple (Cayman) Limited, a limited liability company in the Cayman Islands, on October 25, 2016. In February 2021, the Company deregistered as a Cayman Islands exempted company and continued and domesticated as a corporation incorporated under the laws of the State of Delaware (the “Domestication”). The business, assets and liabilities of the Company and its subsidiaries on a consolidated basis, as well as its principal locations and fiscal year, were the same immediately after the Domestication as they were immediately prior to the Domestication. In addition, the directors and executive officers of the Company immediately after the Domestication were the same individuals who were directors and executive officers, respectively, of the Company immediately prior to the Domestication.
Initial Public Offering And Private Placement	Initial Public Offering and Private Placement On April 19, 2021, the Company closed its initial public offering (“IPO”) and concurrent private placement, in which it issued and sold 27,027,027 shares and 874,999 shares, respectively, of its authorized Class A common stock at $40.00 per share, resulting in net proceeds of $1.0 billion after deducting underwriting discounts and commissions of $50.1 million and offering costs. Upon closing of the IPO, (i) the Company filed an amended and restated certificate of incorporation, which authorized 4,876,000,000 shares of Class A common stock and reclassified all outstanding common stock into Class A common stock, authorized 24,000,000 shares of Class B common stock, which are not publicly traded, and authorized 100,000,000 shares of undesignated preferred stock, (ii) Xiaodi Hou and Mo Chen (the “Founders”) each exchanged 12,000,000 shares of their newly designated Class A common stock for an equivalent number of shares of Class B common stock, and (iii) all shares of the Company’s outstanding redeemable convertible preferred stock automatically converted into 120,534,419 shares of Class A common stock. The rights of the holders of Class A common stock and Class B common stock are identical, except with respect to voting, conversion, and transfer rights. The holders of Class A common stock are entitled to one vote per share and the holders of Class B common stock are entitled to 10 votes per share. Additionally, each share of Class B common stock will automatically convert, on a one-for-one basis, into shares of Class A common stock on the earliest of (i) the date specified by a vote of the holders of Class B common stock representing 75% of the outstanding shares of Class B common stock, (ii) the date that is between 90 days and 270 days, as determined by the board of directors, after the death or incapacitation of the last Founder to die or become incapacitated, or (iii) the date that is between 61 days and 180 days, as determined by the board of directors, after the date on which the number of outstanding shares of Class B common stock held by the Founders (or their permitted affiliates) is less than 12,000,000 shares. Upon the closing of the IPO, the Company recognized $42.6 million of stock-based compensation expense related to stock options, restricted stock units (“RSUs”), and share value awards (“SVAs”), for which the time-based vesting conditions had been satisfied or partially satisfied and the performance-based conditions were satisfied upon the closing of the IPO. Additionally, the Company recorded $4.3 million within operating expenses to former employees in connection with post-employment agreements for which payment was contingent upon the occurrence of an IPO or Sale Event (as such terms are defined in the post-employment agreements).
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The accompanying unaudited condensed consolidated financial statements (“Financial Statements”) have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. The condensed consolidated financial statements include the accounts of the Company and its consolidated subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. These Financial Statements should be read in conjunction with the audited consolidated financial statements and notes included in the Company’s final prospectus filed with the SEC pursuant to Rule 424(b) under the Securities Act of 1933, as amended, on April 16, 2021 (the “Prospectus”).
Stock-Based Compensation	Stock-Based Compensation The Company accounts for stock-based compensation expense in accordance with the fair value recognition and measurement provisions of GAAP, which requires compensation cost for the grant-date fair value of stock-based awards to be recognized over the requisite service period. The Company determines the fair value of stock-based awards granted or modified on the grant date (or modification date, if applicable) at fair value, using appropriate valuation techniques.
Time-Based Service Awards	Time-Based Service Awards For stock-based awards with time-based vesting conditions only, generally being RSUs and stock options, stock-based compensation is recognized straight-line over the requisite service period, which is generally four years. The fair value of RSUs is measured on the grant date based on the closing fair market value of the Company's Class A common stock. The fair value of stock option awards is estimated on the grant date using the Black-Scholes option-pricing model. The Black-Scholes option-pricing model requires the input of highly subjective assumptions, including the fair value of the underlying common stock, the expected stock price volatility over the term of the award, actual and projected employee stock option exercise behaviors, the risk-free interest rate for the expected term of the award and expected dividends. The Company accounts for forfeitures as they occur instead of estimating the number of awards expected to be forfeited.
Employee Stock Purchase Plan ("ESPP")	Employee Stock Purchase Plan ("ESPP") The Company recognizes stock-based expense related to shares issued pursuant to the ESPP on a straight-line basis over the offering period. The ESPP provides for six-month offering periods. The ESPP allows eligible employees to purchase shares of Class A common stock at a 15% discount on the lower of our stock price on either (i) the offering period beginning date or (ii) the purchase date. No employee may purchase shares under the ESPP at a rate in excess of $25,000 worth of Class A common stock based on the fair market value per share of Class A common stock at the beginning of an offering for each calendar year such purchase right is outstanding or 1,500 shares. The Company estimates the fair value of shares to be issued under the ESPP based on a combination of options valued using the Black-Scholes option-pricing model. Volatility is determined over an expected term of six months based on the Company's historical volatility. The expected term is estimated based on the contractual term.
Performance-Based Awards	Performance-Based Awards The Company has granted RSUs, SVAs, and stock options that vest only upon the satisfaction of both time-based service and performance-based conditions. The time-based service condition for these awards generally is satisfied over four years The performance-based conditions, other than with respect to the CEO Performance Award discussed in Note 6. Stock Based Compensation, are satisfied upon the occurrence of a qualifying event, defined as the earlier of (i) the closing of certain specific liquidation or change in control transactions, or (ii) an IPO. The Company records stock-based compensation expense for performance-based equity awards such as RSUs, SVAs, and stock options on an accelerated attribution method over the requisite service period, which is generally four years, and only if performance-based conditions are considered probable to be satisfied. Upon completion of the IPO, the Company recorded a cumulative one-time stock-based compensation expense determined using the grant-date fair values. Stock-based compensation related to remaining time-based service after the qualifying event is recorded over the remaining requisite service period. For performance-based RSUs and SVAs, the Company determines the grant-date fair value as the fair value of the Company’s common stock on the grant date. For performance-based awards with a vesting schedule based entirely on the attainment of both performance and market conditions, stock-based compensation expense associated with each tranche is recognized over the longer of (i) the expected achievement period for the operational milestones for such tranche and (ii) the expected achievement period for the related market capitalization milestone determined on the grant date, beginning at the point in time when the relevant operational milestones are considered probable of being met. If such operational milestones become probable any time after the grant date, the Company will recognize a cumulative catch-up expense from the grant date to that point in time. If the related market capitalization milestone is achieved earlier than its expected achievement period and the achievement of the related operational milestones, then the stock-based compensation expense will be recognized over the expected achievement period for the operational milestones, which may accelerate the rate at which such expense is recognized. The fair value of such awards is estimated on the grant date using Monte Carlo simulations. Refer to Note 6. Stock Based Compensation for further information.
Reclassifications	Reclassifications Certain prior period balances have been reclassified to conform to the current period presentation in the condensed consolidated financial statements and the accompanying notes. Restricted cash has been reclassified to prepaid expenses and other current assets and accrued expenses incurred under joint development agreements have been reclassified to be presented separately from amounts due to related parties.
Recently Adopted and Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements In August 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2018-15, Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that Is a Service Contract , which aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). The Company adopted the guidance as of January 1, 2021 with no material impact to the Financial Statements. In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes . This ASU simplifies the accounting for income taxes by eliminating some exceptions to the general approach in ASC 740, Income Taxes , for recognizing deferred taxes for investments, performing intraperiod allocation and calculating income taxes in interim periods. The Company adopted ASU 2019-12 in the first quarter of 2021 and the adoption had no material impact to the Financial Statements. Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases as modified by subsequently issued ASUs 2018-01, 2018-10 and 2018-11. The core principle of the ASU improves transparency and comparability related to the accounting and reporting of leasing arrangements, including balance sheet recognition for assets and liabilities associated with rights and obligations created by leases with terms greater than twelve months, among other changes. For the Company, the effective date of these ASUs is for fiscal years beginning after December 15, 2021 and early adoption is permitted. The Company has elected not to early adopt these ASUs and plans to elect the modified retrospective application by recording a cumulative effect adjustment to the opening balance of retained earnings in the period of adoption. In addition, the Company expects to avail itself of the package of practical expedients allowing the Company to not reassess (i) whether any expired or existing contracts are or contain leases, (ii) the lease classification for any expired or existing leases, and (iii) the initial direct costs for any existing leases. The Company anticipates recognizing material right-of-use assets and related liabilities upon adoption.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table presents the Company’s assets and liabilities that are measured at fair value on a recurring basis and indicates the fair value hierarchy of the valuation (in thousands): As of December 31, 2020 Total Level 1 Level 2 Level 3 Assets: Cash equivalents: Certificates of deposit $ 279,279 $ 279,279 $ — $ — Total $ 279,279 $ 279,279 $ — $ — Liabilities: Warrants liability $ 42,452 $ — $ — $ 42,452 Total $ 42,452 $ — $ — $ 42,452 As of September 30, 2021 Total Level 1 Level 2 Level 3 Assets: Cash equivalents: Certificates of deposit $ — $ — $ — $ — Money market funds 1,147,989 1,147,989 — — Total $ 1,147,989 $ 1,147,989 $ — $ —
Schedule of Fair Value Assumptions	The Company used the following assumptions in the model: As of December 31, February 26, 2021 March 19, 2021 Discount for lack of marketability 9.00% - 30.00% — — Fair value of underlying securities $14.14 $40.00 $40.00 Expected volatility 53.90% - 76.90% 62.95% 60.85% Expected term (in years) 0.33 - 1.91 1.76 0.79 Risk-free interest rate 0.10% - 0.13% 0.14% 0.08%
Summary of Changes in Estimated Fair Value of Warrants Liability	The following table sets forth a summary of the changes in the estimated fair value of the Company’s warrants liability (in thousands): Balance as of December 31, 2020 $ 42,452 Change in fair value of warrants 326,900 Exercises during the period (369,352) Balance as of September 30, 2021 $ —

Balance Sheet Components (Table

Balance Sheet Components (Tables)	9 Months Ended
	Sep. 30, 2021
Balance Sheet Related Disclosures [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net as of December 31, 2020 and September 30, 2021, was as follows (in thousands): As of December 31, September 30, Electronic equipment $ 11,429 $ 12,396 Office and other equipment 6,152 8,975 Vehicles 12,775 16,369 Leasehold improvements 7,340 10,542 Construction in progress 225 2,985 Property and equipment, gross 37,921 51,267 Accumulated depreciation and amortization (15,805) (21,848) Property and equipment, net $ 22,116 $ 29,419
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities as of December 31, 2020 and September 30, 2021 were as follows (in thousands): As of December 31, September 30, Accrued payroll $ 11,941 $ 24,604 Accrued professional fees 7,865 3,254 Other 3,155 5,248 Accrued expenses and other current liabilities $ 22,961 $ 33,106

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Schedule of Operating Leases	Future minimum lease payments for non-cancelable operating and capital leases as of September 30, 2021 are as follows (in thousands): Year Ending December 31, Operating Leases Capital Leases Remainder of 2021 $ 1,746 $ 341 2022 6,950 1,253 2023 7,136 978 2024 4,870 963 2025 3,418 1,761 Thereafter 21,193 — Total minimum lease payments $ 45,313 5,296 Amount representing interest (1,455) Present value of minimum lease payments $ 3,841
Schedule of Capital Leases	Future minimum lease payments for non-cancelable operating and capital leases as of September 30, 2021 are as follows (in thousands): Year Ending December 31, Operating Leases Capital Leases Remainder of 2021 $ 1,746 $ 341 2022 6,950 1,253 2023 7,136 978 2024 4,870 963 2025 3,418 1,761 Thereafter 21,193 — Total minimum lease payments $ 45,313 5,296 Amount representing interest (1,455) Present value of minimum lease payments $ 3,841

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement, Noncash Expense [Abstract]
Schedule of Estimated Grant-Date Fair Value of ESPP	The estimated grant-date fair value of the ESPP purchase rights was calculated using the Black-Scholes option-pricing model, based on the following assumptions: Three Months Ended September 30, 2021 Nine Months Ended September 30, 2021 Risk-free interest rate 0.06% 0.06% Expected volatility 97.10% 97.10% Expected term (in years) 0.50 0.50 Fair value of common stock $44.39 $44.39
Summary of Stock Option Activities	A summary of the stock option activity, including the CEO Performance Award, for the nine months ended September 30, 2021 is as follows (in thousands, except share amounts, per share amounts, and years): Options Outstanding Weighted- Average Exercise Price Weighted- Average Remaining Life (Years) Aggregate Intrinsic Value Outstanding at December 31, 2020 13,295,497 $ 1.29 7.99 $ 97,986 Granted 3,717,968 $ 22.22 Exercised (244,264) $ 3.20 Cancelled/Forfeited (749,962) $ 1.11 Outstanding at September 30, 2021 16,019,239 $ 6.13 7.66 $ 507,736 Vested and exercisable at September 30, 2021 9,514,873 $ 0.55 6.50 $ 348,041
Summary of Estimated Grant Date Fair Value of Company's Stock Based Option Awards	The estimated grant-date fair value of the Company’s stock-based option awards was calculated using the Black-Scholes option-pricing model, based on the following assumptions: Three Months Ended September 30, Nine Months Ended September 30, 2020 2021 2020 2021 Risk-free interest rate 0.21% - 0.31% 0.86% - 0.95% 0.21% - 0.44% 0.33% - 1.04% Expected volatility 60.00% 50.00% 60.00% 50.00% Expected term (in years) 5.00 - 6.06 6.16 5.00 - 6.06 4.05 - 6.22
Summary of Nonvested Restricted Stock Unit Awards	The following table summarizes the activity related to RSUs for the nine months ended September 30, 2021: RSUs Outstanding Weighted-Average Unvested and outstanding at December 31, 2020 1,100,000 $ 14.14 Granted 4,905,295 $ 50.77 Vested (931,588) $ 19.44 Cancelled (11,928) $ 45.43 Unvested and outstanding at September 30, 2021 5,061,779 $ 48.58 Vested and outstanding at September 30, 2021 142,153 $ 38.19
Summary of Nonvested Shareholder Value Awards Activity	The following table summarizes the activity related to SVAs for the nine months ended September 30, 2021: SVAs Outstanding Weighted-Average Unvested and outstanding at December 31, 2020 3,653,146 $ 3.20 Vested (2,981,349) $ 3.08 Cancelled (260,718) $ 5.84 Unvested and outstanding at September 30, 2021 411,079 $ 4.75 Vested and outstanding at September 30, 2021 — $ —
Summary of Total Stock-based Compensation Expense	Total stock-based compensation expense was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2020 2021 2020 2021 Research and development $ 402 $ 22,382 $ 547 $ 49,520 Sales and marketing 2 101 2 652 General and administrative 7,241 9,599 8,776 40,708 Total stock-based compensation expense $ 7,645 $ 32,082 $ 9,325 $ 90,880

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Summary of Calculation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders	The following table presents the calculation of basic and diluted net loss per share attributable to common stockholders (in thousands, except share and per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2020 2021 2020 2021 Numerator: Net loss $ (89,452) $ (115,490) $ (143,297) $ (617,179) Less: Accretion of redeemable convertible preferred stock (11,943) — (11,943) (4,135) Net loss attributable to common stockholders, basic and diluted $ (101,395) $ (115,490) $ (155,240) $ (621,314) Denominator: Weighted-average shares used in computing net loss per share, basic and diluted 58,606,231 212,802,379 57,584,574 152,469,098 Net loss per share: Net loss per share attributable to common stockholders, basic and diluted $ (1.73) $ (0.54) $ (2.70) $ (4.08)
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following potentially dilutive outstanding shares were excluded from the computation of diluted net loss per share for the periods presented because including them would have had an anti-dilutive effect, or because issuance of such shares is contingent upon the satisfaction of certain conditions which were not satisfied by the end of the period: As of September 30, 2020 2021 Redeemable convertible preferred stock 76,788,483 — Options to purchase common stock 9,760,857 16,019,239 RSUs subject to future vesting — 5,061,779 SVAs subject to future vesting 3,500,815 411,079 Early exercised options subject to future vesting* 1,062,500 45,000 Total 91,112,655 21,537,097 *Refer to Note 6. Stock-Based Compensation for further detail.

Description of Business and S_3

Description of Business and Summary of Significant Accounting Policies (Details)	Apr. 19, 2021USD ($)voted$ / sharesshares	Sep. 30, 2021USD ($)shares	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)shares	Sep. 30, 2020USD ($)	Dec. 31, 2020shares
Description Of Business And Summary Of Significant Accounting Policies Disclosure [Line Items]
Stock-based compensation expense | $		$ 32,082,000	$ 7,645,000	$ 90,880,000	$ 9,325,000
Time Based Service Awards
Description Of Business And Summary Of Significant Accounting Policies Disclosure [Line Items]
Share based compensation, option vesting period				4 years
Performance Based Awards
Description Of Business And Summary Of Significant Accounting Policies Disclosure [Line Items]
Share based compensation, option vesting period				4 years
Employee Stock
Description Of Business And Summary Of Significant Accounting Policies Disclosure [Line Items]
Stock-based compensation expense | $		$ 200,000		$ 200,000
Common Class A
Description Of Business And Summary Of Significant Accounting Policies Disclosure [Line Items]
Common stock, shares authorized (in shares)		4,876,000,000		4,876,000,000		361,897,230
Number of votes per share | vote	1
Maximum purchase amount | $				$ 25,000
Maximum number of shares per employee (in shares)				1,500
Common Class A | Employee Stock
Description Of Business And Summary Of Significant Accounting Policies Disclosure [Line Items]
Offering period				6 months
Purchase price of common stock, percentage of fair market value				15.00%
Common Class B
Description Of Business And Summary Of Significant Accounting Policies Disclosure [Line Items]
Common stock, shares authorized (in shares)		24,000,000		24,000,000		0
Number of votes per share | vote	10
Initial Public Offering
Description Of Business And Summary Of Significant Accounting Policies Disclosure [Line Items]
Preferred stock, authorized (in shares)	100,000,000
Number of redeemable convertible preferred stock converted (in shares)	120,534,419
Stock-based compensation expense | $	$ 42,600,000			$ 42,600,000
Initial Public Offering | Performance Based Awards
Description Of Business And Summary Of Significant Accounting Policies Disclosure [Line Items]
Share based compensation, option vesting period				4 years
Initial Public Offering | Former Employees
Description Of Business And Summary Of Significant Accounting Policies Disclosure [Line Items]
Stock-based compensation expense | $	$ 4,300,000
Initial Public Offering | Common Class A
Description Of Business And Summary Of Significant Accounting Policies Disclosure [Line Items]
Number of shares issued and sold (in shares)	27,027,027
Price per share (in dollars per share) | $ / shares	$ 40
Net proceeds after deducting underwriting discounts and commissions and offering costs | $	$ 1,000,000,000
Underwriting discounts and commissions | $	$ 50,100,000
Common stock, shares authorized (in shares)	4,876,000,000
Number of redeemable convertible preferred stock converted (in shares)	120,534,419
Initial Public Offering | Common Class A | Founders
Description Of Business And Summary Of Significant Accounting Policies Disclosure [Line Items]
Common stock, shares exchanged into Class B common stock (in shares)	12,000,000
Initial Public Offering | Common Class B
Description Of Business And Summary Of Significant Accounting Policies Disclosure [Line Items]
Common stock, shares authorized (in shares)	24,000,000
Percentage of outstanding shares threshold	75.00%
Initial Public Offering | Common Class B | Founders
Description Of Business And Summary Of Significant Accounting Policies Disclosure [Line Items]
Maximum stock conversion outstanding shares threshold	12,000,000
Initial Public Offering | Common Class B | Founders | Minimum
Description Of Business And Summary Of Significant Accounting Policies Disclosure [Line Items]
Stock conversion threshold days | d	61
Initial Public Offering | Common Class B | Founders | Maximum
Description Of Business And Summary Of Significant Accounting Policies Disclosure [Line Items]
Stock conversion threshold days | d	180
Initial Public Offering | Common Class B | Death or Incapacitation of Last Founder | Minimum
Description Of Business And Summary Of Significant Accounting Policies Disclosure [Line Items]
Stock conversion threshold days | d	90
Initial Public Offering | Common Class B | Death or Incapacitation of Last Founder | Maximum
Description Of Business And Summary Of Significant Accounting Policies Disclosure [Line Items]
Stock conversion threshold days | d	270
Private Placement | Common Class A
Description Of Business And Summary Of Significant Accounting Policies Disclosure [Line Items]
Number of shares issued and sold (in shares)	874,999

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Liabilities:
Warrants liability	$ 0	$ 42,452
Recurring Basis
Assets:
Total	1,147,989	279,279
Liabilities:
Total		42,452
Recurring Basis | Level 1
Assets:
Total	1,147,989	279,279
Liabilities:
Warrants liability		0
Total		0
Recurring Basis | Level 2
Assets:
Total	0	0
Liabilities:
Warrants liability		0
Total		0
Recurring Basis | Level 3
Assets:
Total	0	0
Liabilities:
Warrants liability		42,452
Total		42,452
Recurring Basis | Certificates of deposit
Assets:
Cash equivalents	0	279,279
Recurring Basis | Certificates of deposit | Level 1
Assets:
Cash equivalents	0	279,279
Recurring Basis | Certificates of deposit | Level 2
Assets:
Cash equivalents	0	0
Recurring Basis | Certificates of deposit | Level 3
Assets:
Cash equivalents	0	$ 0
Recurring Basis | Money market funds
Assets:
Cash equivalents	1,147,989
Recurring Basis | Money market funds | Level 1
Assets:
Cash equivalents	1,147,989
Recurring Basis | Money market funds | Level 2
Assets:
Cash equivalents	0
Recurring Basis | Money market funds | Level 3
Assets:
Cash equivalents	$ 0

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		9 Months Ended
	Mar. 31, 2021	Feb. 28, 2021	Sep. 30, 2021	Sep. 30, 2020
Fair Value Measurements [Line Items]
Proceeds from warrant exercises			$ 183,007	$ 0
Warrants outstanding (in shares)			0
Series E-2 Preferred Shares | Traton
Fair Value Measurements [Line Items]
Warrants to purchase preferred stock (in shares)		4,331,644
Exercise price per share (in dollars per share)		$ 11.31
Proceeds from warrant exercises		$ 49,000
Series E Redeemable Convertible Preferred Stock | Navistar, Inc.
Fair Value Measurements [Line Items]
Warrants to purchase preferred stock (in shares)	9,477,073
Exercise price per share (in dollars per share)	$ 14.14
Proceeds from warrant exercises	$ 134,000

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value Assumptions (Details)	Mar. 19, 2021$ / shares	Feb. 26, 2021$ / shares	Dec. 31, 2020$ / shares
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value of underlying securities (in dollars per share)	$ 40	$ 40	$ 14.14
Discount for lack of marketability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement input	0	0
Discount for lack of marketability | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement input			0.0900
Discount for lack of marketability | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement input			0.3000
Expected volatility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement input	0.6085	0.6295
Expected volatility | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement input			0.5390
Expected volatility | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement input			0.7690
Expected Term
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Expected term (in years)	9 months 14 days	1 year 9 months 3 days
Expected Term | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Expected term (in years)			3 months 29 days
Expected Term | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Expected term (in years)			1 year 10 months 28 days
Risk-free interest rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement input	0.0008	0.0014
Risk-free interest rate | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement input			0.0010
Risk-free interest rate | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Measurement input			0.0013

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Changes in Estimated Fair Value of Warrants Liability (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Warrant And Right Outstanding Rollforward [Roll Forward]
Beginning balance			$ 42,452
Change in fair value of warrants liability	$ 0	$ 970	326,900	$ 970
Exercises during the period			(369,352)
Ending balance	$ 0		$ 0

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 51,267	$ 37,921
Accumulated depreciation and amortization	(21,848)	(15,805)
Property and equipment, net	29,419	22,116
Electronic equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	12,396	11,429
Office and other equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	8,975	6,152
Vehicles
Property Plant And Equipment [Line Items]
Property and equipment, gross	16,369	12,775
Leasehold improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	10,542	7,340
Construction in progress
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 2,985	$ 225

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Depreciation	$ 2,300	$ 1,800	$ 6,700	$ 5,600
Property and equipment, net	29,419		29,419		$ 22,116
Accumulated amortization	21,848		21,848		15,805
Financed Under Capital Leases
Property Plant And Equipment [Line Items]
Property and equipment, net	4,200		4,200		4,600
Accumulated amortization	$ 2,300		$ 2,300		$ 1,800

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Accrued payroll	$ 24,604	$ 11,941
Accrued professional fees	3,254	7,865
Other	5,248	3,155
Accrued expenses and other current liabilities	$ 33,106	$ 22,961

Commitments and Contingencies -

Commitments and Contingencies - Summary of Future Minimum Lease Payments for Non-cancelable Operating and Capital Leases (Details) $ in Thousands	Sep. 30, 2021USD ($)
Operating Leases
Remainder of 2021	$ 1,746
2022	6,950
2023	7,136
2024	4,870
2025	3,418
Thereafter	21,193
Total minimum lease payments	45,313
Capital Leases
Remainder of 2021	341
2022	1,253
2023	978
2024	963
2025	1,761
Thereafter	0
Total minimum lease payments	5,296
Amount representing interest	(1,455)
Present value of minimum lease payments	$ 3,841

Commitments and Contingencies_2

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	Apr. 19, 2021	Jul. 31, 2020	Apr. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Commitments And Contingencies [Line Items]
Noncancelable operating leases expiration year					$ 1,500
Rental expenses				$ 1,600		$ 4,300	$ 3,900
Research and development				84,506	60,041	204,774	100,202
Proceeds from loans						0	4,134
Stock-based compensation expense				$ 32,082	$ 7,645	90,880	$ 9,325
Initial Public Offering
Commitments And Contingencies [Line Items]
Stock-based compensation expense	$ 42,600					42,600
Former Employees | Initial Public Offering
Commitments And Contingencies [Line Items]
Stock-based compensation expense	$ 4,300
Paycheck Protection Program Loan
Commitments And Contingencies [Line Items]
Proceeds from loans			$ 4,100
Post Employment Agreements | Former Employees | Initial Public Offering
Commitments And Contingencies [Line Items]
Stock-based compensation expense						4,300
Navistar, Inc. | JDA
Commitments And Contingencies [Line Items]
Research and development						$ 10,000
Maximum | Navistar, Inc. | JDA
Commitments And Contingencies [Line Items]
Research and development expenses reimbursement		$ 10,000

Redeemable Convertible Prefer_2

Redeemable Convertible Preferred Stock, Preferred Stock Warrants, and Stockholders’ Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	Apr. 19, 2021	Mar. 31, 2021	Feb. 28, 2021	Jan. 31, 2021	Mar. 31, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Preferred Units [Line Items]
Redeemable convertible preferred stock, shares issued (in shares)							0			102,074,703
Redeemable convertible preferred stock, par value (in dollars per share)							$ 0.0001			$ 0.0001
Proceeds from exercise of warrants for redeemable convertible preferred stock							$ 183,007	$ 0
Redeemable convertible preferred stock, shares outstanding (in shares)							0			102,074,703
Initial Public Offering
Preferred Units [Line Items]
Number of redeemable convertible preferred stock converted (in shares)	120,534,419
Series E Redeemable Convertible Preferred Stock
Preferred Units [Line Items]
Redeemable convertible preferred stock, shares issued (in shares)				4,650,999
Redeemable convertible preferred stock, par value (in dollars per share)				$ 14.14
Proceeds from Issuance of convertible preferred stock, net of issuance costs				$ 61,600
Stock issuance costs				4,100
Accretion of redeemable convertible preferred stock to redemption value				$ 4,100
Series E Redeemable Convertible Preferred Stock | Navistar, Inc.
Preferred Units [Line Items]
Warrants to purchase preferred stock (in shares)		9,477,073			9,477,073
Exercise price per share (in dollars per share)		$ 14.14			$ 14.14
Proceeds from exercise of warrants for redeemable convertible preferred stock		$ 134,000
Series E-2 Redeemable Convertible Preferred Stock | Traton
Preferred Units [Line Items]
Warrants to purchase preferred stock (in shares)			4,331,644
Exercise price per share (in dollars per share)			$ 11.31
Proceeds from exercise of warrants for redeemable convertible preferred stock			$ 49,000
Redeemable convertible preferred stock
Preferred Units [Line Items]
Accretion of redeemable convertible preferred stock to redemption value					$ 4,135	$ 11,943
Redeemable convertible preferred stock, shares outstanding (in shares)		120,534,419			120,534,419	76,788,483	0	76,788,483	0	102,074,703	74,939,388	74,939,388	74,939,388
Redeemable convertible preferred stock | Initial Public Offering
Preferred Units [Line Items]
Redeemable convertible preferred stock, shares issued (in shares)							0
Redeemable convertible preferred stock, shares outstanding (in shares)							0

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) $ / shares in Units, $ in Thousands	Apr. 19, 2021USD ($)	Mar. 31, 2021USD ($)sEMI-TRUCK$ / sharesshares	Apr. 30, 2017	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)$ / sharesshares	Sep. 30, 2020USD ($)	Dec. 31, 2020shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense				$ 32,082	$ 7,645	$ 90,880	$ 9,325
Shares purchased under ESPP (in shares) | shares						0		0
Stock-based compensation						$ 90,880	$ 9,325
Cash proceeds received for unvested shares of common stock						200
Initial Public Offering
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 42,600					$ 42,600
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized share-based compensation expense, weighted-average service period						3 years 4 months 28 days
Unrecognized share-based compensation expense				97,900		$ 97,900
Stock-based compensation	$ 18,800
Stock options exercise price (in dollars per share) | $ / shares						$ 22.22
Stock options contractual life						7 years 7 months 28 days		7 years 11 months 26 days
CEO Performance Award | CEO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized share-based compensation expense, weighted-average service period						3 years 2 months 1 day
Unrecognized share-based compensation expense				27,200		$ 27,200
Stock-based compensation				2,200		5,000
Stock options granted (in shares) | shares		1,150,000
Stock options exercise price (in dollars per share) | $ / shares		$ 14.14
Stock options contractual life		10 years
Average period for market capitalization of the company		180 days
Minimum average market capitalization		$ 25,000,000
Period for average number of semi-trucks operating		90 days
Minimum number of semi-trucks operating on its Autonomous Freight Network | sEMI-TRUCK		1,500
Minimum annual revenue period		12 months
Annual revenue		$ 200,000
RSUs and SVAs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized share-based compensation expense				225,400		$ 225,400
Unrecognized share-based compensation expense, weighted-average service period						3 years 2 months 4 days
Stock-based compensation						$ 23,800
Employee Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense				200		200
Unrecognized share-based compensation expense				$ 800		$ 800
Unrecognized share-based compensation expense, weighted-average service period						4 months 24 days
Class A Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock subject to repurchase (in shares) | shares						45,000
Common stock subject to repurchase at weighted average price per share (in dollars per share) | $ / shares						$ 4.20
Class A Common Stock | Employee Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance (in shares) | shares		2,013,414
Maximum percentage of number of shares for approval		1.00%
2017 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation, option expiry period			10 years
Share based compensation, option vesting period			4 years
Additional common stock reserved for issuance (in shares) | shares		2,300,000
Common stock reserved and authorized (in shares) | shares		24,267,694
2017 Plan | Class A Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance (in shares) | shares		19,892,067
2021 Plan | Class A Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance (in shares) | shares		20,134,146
Maximum percentage of fully diluted capitalization for increase in available stock issuance		5.00%
Percentage of fully-diluted capitalization on last day of preceding fiscal year		2.50%

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Estimated Grant Date Fair Value of ESPP (Details) - Employee Stock	3 Months Ended	9 Months Ended
	Sep. 30, 2021$ / shares	Sep. 30, 2021$ / shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	0.06%	0.06%
Expected volatility	97.10%	97.10%
Expected term (in years)	6 months	6 months
Fair value of common stock (in dollars per share)	$ 44.39	$ 44.39

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Details) - Stock Options $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021USD ($)$ / sharesshares	Dec. 31, 2020USD ($)$ / sharesshares
Options Outstanding
Outstanding, beginning of period (in shares) | shares	13,295,497
Granted (in shares) | shares	3,717,968
Exercised (in shares) | shares	(244,264)
Cancelled/Forfeited (in shares) | shares	(749,962)
Outstanding, end of period (in shares) | shares	16,019,239	13,295,497
Vested and exercisable (in shares) | shares	9,514,873
Weighted-Average Exercise Price
Outstanding, beginning of period (in dollars per share) | $ / shares	$ 1.29
Granted (in dollars per share) | $ / shares	22.22
Exercised (in shares) | $ / shares	3.20
Cancelled/Forfeited (in dollars per share) | $ / shares	1.11
Outstanding, end of period (in dollars per share) | $ / shares	6.13	$ 1.29
Vested and exercisable (in dollars per share) | $ / shares	$ 0.55
Weighted-Average Remaining Life (Years)
Outstanding	7 years 7 months 28 days	7 years 11 months 26 days
Vested and exercisable	6 years 6 months
Aggregate Intrinsic Value
Outstanding | $	$ 507,736	$ 97,986
Vested and exercisable | $	$ 348,041

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Estimated Grant Date Fair Value of Company's Stock Based Option Awards (Details) - Stock Options	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate minimum	0.86%	0.21%	0.33%	0.21%
Risk-free interest rate maximum	0.95%	0.31%	1.04%	0.44%
Expected volatility	50.00%	60.00%	50.00%	60.00%
Expected term (in years)	6 years 1 month 28 days
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)		5 years	4 years 18 days	5 years
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)		6 years 21 days	6 years 2 months 19 days	6 years 21 days

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Nonvested Restricted Stock Unit Awards (Details) - Restricted Stock Units (RSUs)	9 Months Ended
	Sep. 30, 2021$ / sharesshares
RSUs Outstanding
Unvested and Outstanding, Beginning Balance (in shares) | shares	1,100,000
Granted (in shares) | shares	4,905,295
Vested (in shares) | shares	(931,588)
Cancelled (in shares) | shares	(11,928)
Unvested and Outstanding, Ending Balance (in shares) | shares	5,061,779
Vested and Outstanding (in shares) | shares	142,153
Weighted-Average Grant Date Fair Value per Share
Unvested and Outstanding, Beginning Balance (in dollars per share) | $ / shares	$ 14.14
Granted (in dollars per share) | $ / shares	50.77
Vested (in dollars per share) | $ / shares	19.44
Cancelled (in dollars per share) | $ / shares	45.43
Unvested and Outstanding, Ending Balance (in dollars per share) | $ / shares	48.58
Vested and Outstanding (in dollars per share) | $ / shares	$ 38.19

Stock-Based Compensation - Su_4

Stock-Based Compensation - Summary of Nonvested Shareholder Value Awards Activity (Details) - Shareholder Value Awards (SVAs)	9 Months Ended
	Sep. 30, 2021$ / sharesshares
SVAs Outstanding
Unvested and Outstanding, Beginning Balance (in shares) | shares	3,653,146
Vested (in shares) | shares	(2,981,349)
Cancelled (in shares) | shares	(260,718)
Unvested and Outstanding, Ending Balance (in shares) | shares	411,079
Vested and Outstanding (in shares) | shares	0
Weighted-Average Grant Date Fair Value per Share
Unvested and Outstanding, Beginning Balance (in dollars per share) | $ / shares	$ 3.20
Vested (in dollars per share) | $ / shares	3.08
Cancelled (in dollars per share) | $ / shares	5.84
Unvested and Outstanding, Ending Balance (in dollars per share) | $ / shares	4.75
Vested and Outstanding (in dollars per share) | $ / shares	$ 0

Stock-Based Compensation - Su_5

Stock-Based Compensation - Summary of Total Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 32,082	$ 7,645	$ 90,880	$ 9,325
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	22,382	402	49,520	547
Sales and marketing
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	101	2	652	2
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 9,599	$ 7,241	$ 40,708	$ 8,776

Income Taxes (Details)

Income Taxes (Details)	9 Months Ended
	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Effective tax rate	0.00%
Effective income tax U.S. federal rate	21.00%

Net Loss Per Share Attributab_3

Net Loss Per Share Attributable to Common Stockholders - Summary of Calculation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net loss	$ (115,490)	$ (89,452)	$ (617,179)	$ (143,297)
Less: Accretion of redeemable convertible preferred stock	0	(11,943)	(4,135)	(11,943)
Net loss attributable to common stockholders, basic	(115,490)	(101,395)	(621,314)	(155,240)
Net loss attributable to common stockholders, diluted	$ (115,490)	$ (101,395)	$ (621,314)	$ (155,240)
Denominator:
Weighted-average shares used in computing net loss per share, basic (in shares)	212,802,379	58,606,231	152,469,098	57,584,574
Weighted-average shares used in computing net loss per share, diluted (in shares)	212,802,379	58,606,231	152,469,098	57,584,574
Net loss per share:
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (0.54)	$ (1.73)	$ (4.08)	$ (2.70)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (0.54)	$ (1.73)	$ (4.08)	$ (2.70)

Net Loss Per Share Attributab_4

Net Loss Per Share Attributable to Common Stockholders - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Details) - shares	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	21,537,097	91,112,655
Redeemable convertible preferred stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	0	76,788,483
Options to purchase common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	16,019,239	9,760,857
RSUs subject to future vesting
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	5,061,779	0
SVAs subject to future vesting
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	411,079	3,500,815
Early exercised options subject to future vesting
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	45,000	1,062,500

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2021
Related Party Transaction [Line Items]
Amounts due to related parties	$ 4,360	$ 0
Executive Chairman And Director
Related Party Transaction [Line Items]
Outstanding loans	600
Jinzhuo Hengbang Technology (Beijing) Co., Ltd.
Related Party Transaction [Line Items]
Amounts due to related parties	3,700
Sina Corporation
Related Party Transaction [Line Items]
Payments of guarantee deposit on loan borrowed	$ 3,700

Redeemable Convertible Prefer_3

Redeemable Convertible Preferred Stock, Preferred Stock Warrants, and Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Apr. 19, 2021	Mar. 31, 2021	Feb. 28, 2021	Jan. 31, 2021	Mar. 31, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Schedule Of Capitalization Equity [Line Items]
Redeemable convertible preferred stock, shares issued (in shares)							0			102,074,703
Redeemable convertible preferred stock, par value (in dollars per share)							$ 0.0001			$ 0.0001
Proceeds from warrant exercises							$ 183,007	$ 0
Redeemable convertible preferred stock, shares outstanding (in shares)							0			102,074,703
Initial Public Offering
Schedule Of Capitalization Equity [Line Items]
Number of redeemable convertible preferred stock converted (in shares)	120,534,419
Series E Redeemable Convertible Preferred Stock
Schedule Of Capitalization Equity [Line Items]
Redeemable convertible preferred stock, shares issued (in shares)				4,650,999
Redeemable convertible preferred stock, par value (in dollars per share)				$ 14.14
Proceeds from Issuance of convertible preferred stock, net of issuance costs				$ 61,600
Stock issuance costs				4,100
Temporary equity accretion to redemption value				$ 4,100
Series E Redeemable Convertible Preferred Stock | Navistar, Inc.
Schedule Of Capitalization Equity [Line Items]
Warrants to purchase preferred stock (in shares)		9,477,073			9,477,073
Exercise price per share (in dollars per share)		$ 14.14			$ 14.14
Proceeds from warrant exercises		$ 134,000
Series E-2 Redeemable Convertible Preferred Stock | Traton
Schedule Of Capitalization Equity [Line Items]
Warrants to purchase preferred stock (in shares)			4,331,644
Exercise price per share (in dollars per share)			$ 11.31
Proceeds from warrant exercises			$ 49,000
Redeemable convertible preferred stock
Schedule Of Capitalization Equity [Line Items]
Temporary equity accretion to redemption value					$ 4,135	$ 11,943
Redeemable convertible preferred stock, shares outstanding (in shares)		120,534,419			120,534,419	76,788,483	0	76,788,483	0	102,074,703	74,939,388	74,939,388	74,939,388
Redeemable convertible preferred stock | Initial Public Offering
Schedule Of Capitalization Equity [Line Items]
Redeemable convertible preferred stock, shares issued (in shares)							0
Redeemable convertible preferred stock, shares outstanding (in shares)							0