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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.