Convertible Preferred Stock and Stockholders' Equity (Deficit)	12 Months Ended
Dec. 31, 2019
Equity [Abstract]
Convertible Preferred Stock and Stockholders' Equity (Deficit)	Note 9—Convertible Preferred Stock and Stockholders’ Equity (Deficit) Convertible Preferred Stock Series Seed Convertible Preferred Stock On January 4, 2018, the Company issued an aggregate of 20,000,000 shares of Series Seed Convertible Preferred Stock in connection with the merger agreement with AA Biopharma Inc. (See Note 7). Series A Convertible Preferred Stock In January and March 2018, the Company issued an aggregate of 45,714,286 shares of Series A Convertible Preferred Stock at $1.75 per share for approximately $73.9 million in cash and the conversion of approximately $6.1 million in principal and accrued interest under the Note (See Note 6). Series B Convertible Preferred Stock On July 20, 2018, the Company issued an aggregate of 71,506,513 shares of Series B Convertible Preferred Stock at $3.2167 per share for approximately $230.0 million in gross proceeds. The Series Convertible Preferred Stock was classified outside of stockholders’ equity (deficit) because the shares contained certain redemption features that were not solely within the control of the Company. In connection with the Company’s IPO, the outstanding shares of the Company’s Series Seed, Series A, and Series B Convertible Preferred Stock automatically converted into 30,493,460 shares of common stock. Common Stock On December 3, 2015, the Company issued 9,160,888 shares of common stock as founder shares for services rendered to the Company, valued at $0.0001 par value per share, for a total of approximately $4,100 (the “Founders’ Equity”). On January 4, 2018, incremental vesting conditions were placed on the previously issued founder shares. Fifty percent of the previously issued founder shares vested on January 4, 2018, and the remaining founder shares are subject to vesting restrictions over a period of five years. Pursuant to the employment agreements with the Company’s founders executed January 4, 2018, the Company provided for certain potential additional issuances of common stock (the “anti-dilution shares”) to each of the founders to ensure the total number of shares of common stock held by them and their affiliates (inclusive of any shares subject to equity awards granted by the Company and the Founders’ Equity) would represent 15% of the Company’s fully-diluted capitalization until such time as the Company raised $300 million in equity capital, including the capital raised in the Series A financing. In furtherance of this obligation, on May 21, 2018, the Company issued 251,547 shares of common stock to the founders for services rendered to the Company, valued at $2.61 per share with an additional 251,547 shares of restricted stock subject to the same vesting restrictions and vesting period as the founder shares. In addition, on September 6, 2018, the Company issued 1,795,023 shares of common stock to the founders for services rendered to the Company, valued at $9.63 per share, with an additional 1,795,023 shares of restricted stock subject to the same vesting restrictions and vesting period as the founder shares. Each share of common stock is entitled to one voting right. Common stock owners are entitled to dividends when funds are legally available and declared by the Board. Shares of Common Stock Subject to Repurchase In November 2017, in connection with the issuance of the Series A Convertible Preferred Stock, certain employees entered into stock restriction agreements, whereby 1,305,421 shares are subject to forfeiture by the Company upon the stockholder’s termination of employment or service to the Company. In January 2018, the Company’s founders entered into stock restriction agreements, whereby 4,580,444 of previously unrestricted shares of common stock were subject to service vesting conditions. These shares are also subject to forfeiture by the Company upon the stockholders’ termination of employment or service to the Company. Any shares subject to repurchase by the Company are not deemed, for accounting purposes, to be outstanding until those shares vest. As such, the Company recognizes the measurement date fair value of the restricted stock over the vesting period as compensation expense. For the years ended December 31, 2019, 2018 and 2017, 4,648,526 shares, 7,482,032 shares and 1,305,421 shares of common stock, respectively, were subject to repurchase by the Company. The unvested stock liability related to these awards is immaterial to all periods presented.

Convertible Preferred Stock and Stockholders' Equity (Deficit)

12 Months Ended

Dec. 31, 2019

Convertible Preferred Stock and Stockholders' Equity (Deficit)

Note 9—Convertible Preferred Stock and Stockholders’ Equity (Deficit)

Convertible Preferred Stock

Series Seed Convertible Preferred Stock

On January 4, 2018, the Company issued an aggregate of 20,000,000 shares of Series Seed Convertible Preferred Stock in connection with the merger agreement with AA Biopharma Inc. (See Note 7).

Series A Convertible Preferred Stock

In January and March 2018, the Company issued an aggregate of 45,714,286 shares of Series A Convertible Preferred Stock at $1.75 per share for approximately $73.9 million in cash and the conversion of approximately $6.1 million in principal and accrued interest under the Note (See Note 6).

Series B Convertible Preferred Stock

On July 20, 2018, the Company issued an aggregate of 71,506,513 shares of Series B Convertible Preferred Stock at $3.2167 per share for approximately $230.0 million in gross proceeds.

The Series Convertible Preferred Stock was classified outside of stockholders’ equity (deficit) because the shares contained certain redemption features that were not solely within the control of the Company. In connection with the Company’s IPO, the outstanding shares of the Company’s Series Seed, Series A, and Series B Convertible Preferred Stock automatically converted into 30,493,460 shares of common stock.

Common Stock

On December 3, 2015, the Company issued 9,160,888 shares of common stock as founder shares for services rendered to the Company, valued at $0.0001 par value per share, for a total of approximately $4,100 (the “Founders’ Equity”). On January 4, 2018, incremental vesting conditions were placed on the previously issued founder shares. Fifty percent of the previously issued founder shares vested on January 4, 2018, and the remaining founder shares are subject to vesting restrictions over a period of five years.

Pursuant to the employment agreements with the Company’s founders executed January 4, 2018, the Company provided for certain potential additional issuances of common stock (the “anti-dilution shares”) to each of the founders to ensure the total number of shares of common stock held by them and their affiliates (inclusive of any shares subject to equity awards granted by the Company and the Founders’ Equity) would represent 15% of the Company’s fully-diluted capitalization until such time as the Company raised $300 million in equity capital, including the capital raised in the Series A financing.

In furtherance of this obligation, on May 21, 2018, the Company issued 251,547 shares of common stock to the founders for services rendered to the Company, valued at $2.61 per share with an additional 251,547 shares of restricted stock subject to the same vesting restrictions and vesting period as the founder shares. In addition, on September 6, 2018, the Company issued 1,795,023 shares of common stock to the founders for services rendered to the Company, valued at $9.63 per share, with an additional 1,795,023 shares of restricted stock subject to the same vesting restrictions and vesting period as the founder shares.

Each share of common stock is entitled to one voting right. Common stock owners are entitled to dividends when funds are legally available and declared by the Board.

Shares of Common Stock Subject to Repurchase

In November 2017, in connection with the issuance of the Series A Convertible Preferred Stock, certain employees entered into stock restriction agreements, whereby 1,305,421 shares are subject to forfeiture by the Company upon the stockholder’s termination of employment or service to the Company. In January 2018, the Company’s founders entered into stock restriction agreements, whereby 4,580,444 of previously unrestricted shares of common stock were subject to service vesting conditions. These shares are also subject to forfeiture by the Company upon the stockholders’ termination of employment or service to the Company. Any shares subject to repurchase by the Company are not deemed, for accounting purposes, to be outstanding until those shares vest. As such, the Company recognizes the measurement date fair value of the restricted stock over the vesting period as compensation expense. For the years ended December 31, 2019, 2018 and 2017, 4,648,526 shares, 7,482,032 shares and 1,305,421 shares of common stock, respectively, were subject to repurchase by the Company. The unvested stock liability related to these awards is immaterial to all periods presented.