Organization	9 Months Ended
Sep. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization	Note 1. Organization Description of Business Arcus Biosciences, Inc. (Company or the Company) is a clinical-stage biopharmaceutical company focused on creating innovative cancer immunotherapies by leveraging underexploited biological opportunities. Specifically, the Company targets well-characterized biological pathways with significant scientific data supporting their importance in regulating the immune response against cancer and for which either there are no molecules in development or those that exist have suboptimal profiles. To exploit these pathways, the Company has built a robust and highly efficient discovery capability to create and optimize highly differentiated small-molecule immuno-oncology product candidates. Since its inception in 2015, the Company has built a broad portfolio of small molecule and antibody product candidates that it plans to develop together as intra-portfolio combinations. Initial Public Offering On March 21, 2018, the Company completed its initial public offering (IPO) pursuant to which the Company issued 9,200,000 shares of common stock, including the exercise of the underwriters’ overallotment option to purchase 1,200,000 shares of common stock, at an offering price at $15.00 per share. The Company received aggregate net proceeds of approximately $124.7 million after deducting underwriting discounts and other offering related costs. In addition, in connection with the completion of the Company’s IPO, all outstanding shares of convertible preferred stock were converted into 30,459,574 shares of common stock and the Company amended and restated its certificate of incorporation and bylaws, which, among other things, changed the authorized capital stock to 400,000,000 shares of common stock and 10,000,000 shares of preferred stock, each with a par value of $0.0001 per share. Liquidity and Capital Resources As of September 30, 2018, the Company had cash and investments of $265.6 million, of which $257.8 million are cash, cash equivalents, and short-term investments which the Company believes will be sufficient to fund its planned operations for a period of at least twelve months following the filing date of this report.

Note 1. Organization

Description of Business

Arcus Biosciences, Inc. (Company or the Company) is a clinical-stage biopharmaceutical company focused on creating innovative cancer immunotherapies by leveraging underexploited biological opportunities. Specifically, the Company targets well-characterized biological pathways with significant scientific data supporting their importance in regulating the immune response against cancer and for which either there are no molecules in development or those that exist have suboptimal profiles. To exploit these pathways, the Company has built a robust and highly efficient discovery capability to create and optimize highly differentiated small-molecule immuno-oncology product candidates. Since its inception in 2015, the Company has built a broad portfolio of small molecule and antibody product candidates that it plans to develop together as intra-portfolio combinations.

Initial Public Offering

On March 21, 2018, the Company completed its initial public offering (IPO) pursuant to which the Company issued 9,200,000 shares of common stock, including the exercise of the underwriters’ overallotment option to purchase 1,200,000 shares of common stock, at an offering price at $15.00 per share. The Company received aggregate net proceeds of approximately $124.7 million after deducting underwriting discounts and other offering related costs. In addition, in connection with the completion of the Company’s IPO, all outstanding shares of convertible preferred stock were converted into 30,459,574 shares of common stock and the Company amended and restated its certificate of incorporation and bylaws, which, among other things, changed the authorized capital stock to 400,000,000 shares of common stock and 10,000,000 shares of preferred stock, each with a par value of $0.0001 per share.

Liquidity and Capital Resources

As of September 30, 2018, the Company had cash and investments of $265.6 million, of which $257.8 million are cash, cash equivalents, and short-term investments which the Company believes will be sufficient to fund its planned operations for a period of at least twelve months following the filing date of this report.