License and Collaboration Agreements	12 Months Ended
Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
License and Collaboration Agreements	Note 6. License and Collaboration Agreements Taiho Pharmaceutical Co., Ltd In September 2017, the Company and Taiho entered into an option and license agreement (the Taiho Agreement) to collaborate on the potential development and commercialization of certain product candidates from the Company’s portfolio in Japan and certain other territories in Asia (excluding China) (the Taiho Territory). The Taiho Agreement provides Taiho with exclusive options, over a five-year period (the Option Period), to obtain an exclusive development and commercialization license to clinical stage product candidates from the Company’s programs (each, an Arcus Program). In consideration for the exclusive options and other rights contained in the Taiho Agreement, Taiho will make non-refundable, non-creditable cash payments to the Company totaling $35.0 million, of which the Company received $25.0 million during 2017. An additional $5.0 million was received in October 2018 and the remaining $5.0 million is expected to be received in 2019. In the event that the Company has not initiated IND enabling studies for at least five Arcus Programs prior to the expiration of the Option Period, Taiho may elect to extend the Option Period, up to a maximum of seven years for the Option Period, subject to an extension fee. If Taiho elects to exercise an option they will be obligated to make an exercise option payment for each option exercise of between $3.0 million to $15.0 million, dependent on the development stage of the applicable Arcus Program for which the option is exercised. In addition, the Taiho Agreement provides that the Company is eligible to receive additional clinical and regulatory milestones totaling up to $130.0 million per Arcus Program, and it will be eligible to receive contingent payments of up to $145.0 million per Arcus Program associated with the achievement of specified levels of Taiho net sales in the Taiho Territory. In addition, the Company will receive royalties ranging from high single-digits to mid-teens on net sales of licensed products in the Taiho Territory. Royalties will be payable on a licensed product-by-licensed product and country-by-country basis during the period of time commencing on the first commercial sale of a licensed product in a country and ending upon the later of: (a) ten (10) years from the date of first commercial sale of such licensed product in such country; and (b) expiration of the last-to-expire valid claim of the Company’s patents covering the manufacture, use or sale or exploitation of such licensed product in such country (the Royalty Term). The Taiho Agreement contains multiple elements, and the deliverables under the Taiho Agreement consist of (1) the research and development services, in which the Company will use commercially reasonable efforts to initiate IND enabling studies for at least five Arcus Programs, as well as further develop such Arcus Programs during the term of the Agreement, and (2) the obligation to participate on the joint steering committee. These deliverables are non-contingent in nature. The Company determined that the obligation to participate in the joint steering committee does not have stand-alone value to Taiho because the committee’s primary purpose is to monitor and govern the research and development activities and, hence, it is inseparable from the research and development services. The Company determined that the level of effort required for it to meet its obligations under the Taiho Agreement is not expected to vary significantly over the Company’s performance period. Accordingly, the Company combined these deliverables into a single unit of accounting and allocated the entire arrangement consideration to that combined unit of accounting. As a result, the $25.0 million non-refundable, non-creditable cash payments received by the Company in 2017 is being recognized ratably over the estimated performance period of five years, the $5.0 million non-refundable, non-creditable cash payment received by the Company in 2018 is being recognized ratably over the estimated performance period of four years and the remaining $5.0 million of non-refundable, non-creditable cash payments will be recognized ratably over the estimated remaining performance period as it becomes due and payable by Taiho. The Company also concluded that, at the inception of the agreement, Taiho’s exclusive options are substantive and that they are contingent deliverables as the exclusive options have significant uncertainty and are outside of the control of the Company, since Taiho has sole discretion to determine whether or not to exercise such options. Further, the Company concluded that the exclusive options do not contain a significant and incremental discount. In July 2018, Taiho exercised its option to the Company’s adenosine receptor antagonist program for a fee of $3.0 million, which was recognized by the Company as revenue during the year ended December 31, 2018. Upon this option exercise, Taiho now has the sole responsibility for the development and commercialization of licensed products from within the program in the Taiho Territory. The Company also determined that the clinical and regulatory milestone payments under the Taiho Agreement do not constitute substantive milestones and, therefore, will not be accounted for under the milestone method of revenue recognition. The events leading to these payments do not meet the definition of a substantive milestone because the achievement of these events depends primarily on Taiho’s performance. Accordingly, any revenue from these payments would be recognized over the remaining period of the performance obligations, if any, relating to this arrangement. If there are no remaining performance obligations under the arrangement at the time the milestone payment is triggered, then such milestone payment will be recognized as revenue in full upon the triggering event being achieved. As of December 31, 2018, no clinical and regulatory milestones had been achieved. During the years ended December 31, 2018 and 2017, the Company recognized a total of $8.3 million and $1.4 million, respectively, of revenue under the Taiho Agreement. As of December 31, 2018, the Company recorded as deferred revenue, current and deferred revenue, noncurrent of $6.3 million and $17.0 million, respectively, in its consolidated balance sheet. As of December 31, 2017, the Company recorded as deferred revenue, current and deferred revenue, noncurrent of $5.0 million and $18.6 million, respectively, in its consolidated balance sheet. The Company considers the contingent payments due from Taiho upon the achievement of specified sales volumes to be similar to royalty payments. The Company will recognize royalty payments as revenue in the period when such royalty payments are earned, i.e. in the period when sales of the licensed products in Taiho Territory occur. The Taiho Agreement shall remain in effect until (a) expiration of the last exercise period if Taiho has not exercised any of its exclusive options prior to such expiration or (b) if Taiho has exercised any of its exclusive options prior to the expiration of the applicable exercise period, expiry of all Royalty Terms for the licensed products, in each case subject to certain exceptions. WuXi Biologics License Agreement In August 2017, the Company entered into a license agreement (the WuXi Agreement) with WuXi Biologics (Cayman) Inc. (WuXi Biologics) in which it obtained an exclusive license to develop, use, manufacture, and commercialize products including an anti-PD-1 antibody in North America, Europe, Japan and certain other territories. The Company paid upfront and milestone payments of $18.5 million during 2017 which were recorded within research and development expenses, as the products had not reached technological feasibility and did not have alternative future. No milestone payments were made during the year ended December 31, 2018. The WuXi Agreement also provides for clinical and regulatory milestone payments, commercialization milestone payments of up to $375.0 million, and tiered royalty payments to be made to WuXi Biologics that range from the high single-digits to low teens of net sales by the Company of licensed products. Abmuno License Agreement In December 2016, the Company entered into a license agreement (the Abmuno Agreement) with Abmuno Therapeutics LLC (Abmuno) in which it obtained a worldwide exclusive license to develop, use, manufacture, and commercialize products that include an anti-TIGIT antibody. The Company made milestone payments of $2.8 million for the year ended December 31, 2018 and upfront and milestone payments of $3.8 million for the year ended December 31, 2017, which were recorded within research and development expenses, as the products have not reached technological feasibility and do not have alternative future use and were expensed as incurred. The Abmuno Agreement also provides for additional clinical, regulatory and commercialization milestone payments of up to $101.0 million as of December 31, 2018.

License and Collaboration Agreements

12 Months Ended

Dec. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Note 6. License and Collaboration Agreements

Taiho Pharmaceutical Co., Ltd

In September 2017, the Company and Taiho entered into an option and license agreement (the Taiho Agreement) to collaborate on the potential development and commercialization of certain product candidates from the Company’s portfolio in Japan and certain other territories in Asia (excluding China) (the Taiho Territory). The Taiho Agreement provides Taiho with exclusive options, over a five-year period (the Option Period), to obtain an exclusive development and commercialization license to clinical stage product candidates from the Company’s programs (each, an Arcus Program).

In consideration for the exclusive options and other rights contained in the Taiho Agreement, Taiho will make non-refundable, non-creditable cash payments to the Company totaling $35.0 million, of which the Company received $25.0 million during 2017. An additional $5.0 million was received in October 2018 and the remaining $5.0 million is expected to be received in 2019.

In the event that the Company has not initiated IND enabling studies for at least five Arcus Programs prior to the expiration of the Option Period, Taiho may elect to extend the Option Period, up to a maximum of seven years for the Option Period, subject to an extension fee. If Taiho elects to exercise an option they will be obligated to make an exercise option payment for each option exercise of between $3.0 million to $15.0 million, dependent on the development stage of the applicable Arcus Program for which the option is exercised. In addition, the Taiho Agreement provides that the Company is eligible to receive additional clinical and regulatory milestones totaling up to $130.0 million per Arcus Program, and it will be eligible to receive contingent payments of up to $145.0 million per Arcus Program associated with the achievement of specified levels of Taiho net sales in the Taiho Territory.

In addition, the Company will receive royalties ranging from high single-digits to mid-teens on net sales of licensed products in the Taiho Territory. Royalties will be payable on a licensed product-by-licensed product and country-by-country basis during the period of time commencing on the first commercial sale of a licensed product in a country and ending upon the later of: (a) ten (10) years from the date of first commercial sale of such licensed product in such country; and (b) expiration of the last-to-expire valid claim of the Company’s patents covering the manufacture, use or sale or exploitation of such licensed product in such country (the Royalty Term).

The Taiho Agreement contains multiple elements, and the deliverables under the Taiho Agreement consist of (1) the research and development services, in which the Company will use commercially reasonable efforts to initiate IND enabling studies for at least five Arcus Programs, as well as further develop such Arcus Programs during the term of the Agreement, and (2) the obligation to participate on the joint steering committee. These deliverables are non-contingent in nature. The Company determined that the obligation to participate in the joint steering committee does not have stand-alone value to Taiho because the committee’s primary purpose is to monitor and govern the research and development activities and, hence, it is inseparable from the research and development services.

The Company determined that the level of effort required for it to meet its obligations under the Taiho Agreement is not expected to vary significantly over the Company’s performance period. Accordingly, the Company combined these deliverables into a single unit of accounting and allocated the entire arrangement consideration to that combined unit of accounting. As a result, the $25.0 million non-refundable, non-creditable cash payments received by the Company in 2017 is being recognized ratably over the estimated performance period of five years, the $5.0 million non-refundable, non-creditable cash payment received by the Company in 2018 is being recognized ratably over the estimated performance period of four years and the remaining $5.0 million of non-refundable, non-creditable cash payments will be recognized ratably over the estimated remaining performance period as it becomes due and payable by Taiho.

The Company also concluded that, at the inception of the agreement, Taiho’s exclusive options are substantive and that they are contingent deliverables as the exclusive options have significant uncertainty and are outside of the control of the Company, since Taiho has sole discretion to determine whether or not to exercise such options. Further, the Company concluded that the exclusive options do not contain a significant and incremental discount. In July 2018, Taiho exercised its option to the Company’s adenosine receptor antagonist program for a fee of $3.0 million, which was recognized by the Company as revenue during the year ended December 31, 2018. Upon this option exercise, Taiho now has the sole responsibility for the development and commercialization of licensed products from within the program in the Taiho Territory.

The Company also determined that the clinical and regulatory milestone payments under the Taiho Agreement do not constitute substantive milestones and, therefore, will not be accounted for under the milestone method of revenue recognition. The events leading to these payments do not meet the definition of a substantive milestone because the achievement of these events depends primarily on Taiho’s performance. Accordingly, any revenue from these payments would be recognized over the remaining period of the performance obligations, if any, relating to this arrangement. If there are no remaining performance obligations under the arrangement at the time the milestone payment is triggered, then such milestone payment will be recognized as revenue in full upon the triggering event being achieved. As of December 31, 2018, no clinical and regulatory milestones had been achieved.

During the years ended December 31, 2018 and 2017, the Company recognized a total of $8.3 million and $1.4 million, respectively, of revenue under the Taiho Agreement. As of December 31, 2018, the Company recorded as deferred revenue, current and deferred revenue, noncurrent of $6.3 million and $17.0 million, respectively, in its consolidated balance sheet. As of December 31, 2017, the Company recorded as deferred revenue, current and deferred revenue, noncurrent of $5.0 million and $18.6 million, respectively, in its consolidated balance sheet.

The Company considers the contingent payments due from Taiho upon the achievement of specified sales volumes to be similar to royalty payments. The Company will recognize royalty payments as revenue in the period when such royalty payments are earned, i.e. in the period when sales of the licensed products in Taiho Territory occur. The Taiho Agreement shall remain in effect until (a) expiration of the last exercise period if Taiho has not exercised any of its exclusive options prior to such expiration or (b) if Taiho has exercised any of its exclusive options prior to the expiration of the applicable exercise period, expiry of all Royalty Terms for the licensed products, in each case subject to certain exceptions.

WuXi Biologics License Agreement

In August 2017, the Company entered into a license agreement (the WuXi Agreement) with WuXi Biologics (Cayman) Inc. (WuXi Biologics) in which it obtained an exclusive license to develop, use, manufacture, and commercialize products including an anti-PD-1 antibody in North America, Europe, Japan and certain other territories. The Company paid upfront and milestone payments of $18.5 million during 2017 which were recorded within research and development expenses, as the products had not reached technological feasibility and did not have alternative future. No milestone payments were made during the year ended December 31, 2018. The WuXi Agreement also provides for clinical and regulatory milestone payments, commercialization milestone payments of up to $375.0 million, and tiered royalty payments to be made to WuXi Biologics that range from the high single-digits to low teens of net sales by the Company of licensed products.

Abmuno License Agreement

In December 2016, the Company entered into a license agreement (the Abmuno Agreement) with Abmuno Therapeutics LLC (Abmuno) in which it obtained a worldwide exclusive license to develop, use, manufacture, and commercialize products that include an anti-TIGIT antibody. The Company made milestone payments of $2.8 million for the year ended December 31, 2018 and upfront and milestone payments of $3.8 million for the year ended December 31, 2017, which were recorded within research and development expenses, as the products have not reached technological feasibility and do not have alternative future use and were expensed as incurred. The Abmuno Agreement also provides for additional clinical, regulatory and commercialization milestone payments of up to $101.0 million as of December 31, 2018.