License Agreement	12 Months Ended
Dec. 31, 2018
Revenue From Contract With Customer [Abstract]
License Agreement	15. License Agreement On June 24, 2018, the Company entered into a License Agreement (the “Gossamer License”) with a wholly-owned subsidiary of Gossamer Bio, Inc., GB004, Inc. (collectively “Gossamer”), under which the Company granted Gossamer an exclusive, sublicensable license to develop and commercialize AKB-4924 and other structurally related products worldwide, with initial development expected in the indications of induction and maintenance in ulcerative colitis and Crohn’s Disease (collectively “initial indications”). Prior to the execution of the Gossamer License, AKB-4924 was a pipeline program for the Company that recently completed a Phase 1a clinical trial in healthy volunteers. Gossamer is responsible for the development and commercialization of the licensed products, and a joint development committee has been formed to oversee the development and manufacturing activities related to the licensed products. Under the terms of the Gossamer License, Gossamer is obligated to use its commercially reasonable efforts to develop and commercialize licensed products in the United States, two major European countries and Japan for at least one of the initial indications. The Gossamer License includes an exclusivity provision that prohibits the Company from developing, manufacturing or commercializing, and prohibits Gossamer from clinically developing or commercializing certain HIF stabilizing compounds other than as permitted in the Gossamer License. Pursuant to the terms of the Gossamer License, Gossamer made an upfront payment to the Company of $20.0 million on June 28, 2018. The $20.0 million of license revenue is recorded within the consolidated statement of operations and comprehensive loss for the year ended December 31, 2018. The Company is also eligible to receive development, commercial and sales milestone payments, with such payments contingent on the achievement of specified milestones with respect to the first licensed product for each of the first two initial indications. The Company is also eligible to receive tiered royalties on sales of licensed products at percentages ranging from a high-single-digit to mid-teens, subject to certain customary reductions. In addition, under certain circumstances, in lieu of receiving the foregoing milestone payments and royalties, the Company may elect to receive a specified percentage of payments received by Gossamer and its stockholders (with some exclusions) in connection with Gossamer’s grant of a sublicense or other rights to the licensed products or if Gossamer undergoes a change of control and the value of the transaction exceeds a certain value (provided that Gossamer can prevent the Company from exercising this option if the parent company of Gossamer is the entity undergoing the change of control). Conversely, the Company could be required to accept such a specified percentage of those payments if Gossamer agrees to pay the Company a certain minimum upon Gossamer and its stockholders being paid. Such amount may be reduced if the subject transaction includes pharmaceutical candidates or products or other named asset categories in addition to the licensed products. The Gossamer License expires on a licensed-product-by-licensed-product and country-by-country basis on the later of fifteen years from the date of first commercial sale or when there is no longer a valid patent claim covering such licensed product in such country. Either party may terminate the Gossamer License for an uncured material breach by the other party or upon the bankruptcy or insolvency of the other party. Gossamer may terminate the Gossamer License in the event Gossamer determines there is a potential safety or efficacy issue with the licensed products. The Company may terminate the Gossamer License if Gossamer institutes certain actions related to the licensed patents. Under certain termination circumstances, the Company would have worldwide rights to the terminated program. As of December 31, 2018, all development milestones, sales-based milestones and royalty payments within the Gossamer License are constrained to the point where no transaction price has been allocated to the future milestones or royalty payments.

License Agreement

12 Months Ended

Dec. 31, 2018

Revenue From Contract With Customer [Abstract]

15. License Agreement

On June 24, 2018, the Company entered into a License Agreement (the “Gossamer License”) with a wholly-owned subsidiary of Gossamer Bio, Inc., GB004, Inc. (collectively “Gossamer”), under which the Company granted Gossamer an exclusive, sublicensable license to develop and commercialize AKB-4924 and other structurally related products worldwide, with initial development expected in the indications of induction and maintenance in ulcerative colitis and Crohn’s Disease (collectively “initial indications”). Prior to the execution of the Gossamer License, AKB-4924 was a pipeline program for the Company that recently completed a Phase 1a clinical trial in healthy volunteers.

Gossamer is responsible for the development and commercialization of the licensed products, and a joint development committee has been formed to oversee the development and manufacturing activities related to the licensed products. Under the terms of the Gossamer License, Gossamer is obligated to use its commercially reasonable efforts to develop and commercialize licensed products in the United States, two major European countries and Japan for at least one of the initial indications. The Gossamer License includes an exclusivity provision that prohibits the Company from developing, manufacturing or commercializing, and prohibits Gossamer from clinically developing or commercializing certain HIF stabilizing compounds other than as permitted in the Gossamer License. Pursuant to the terms of the Gossamer License, Gossamer made an upfront payment to the Company of $20.0 million on June 28, 2018. The $20.0 million of license revenue is recorded within the consolidated statement of operations and comprehensive loss for the year ended December 31, 2018.

The Company is also eligible to receive development, commercial and sales milestone payments, with such payments contingent on the achievement of specified milestones with respect to the first licensed product for each of the first two initial indications. The Company is also eligible to receive tiered royalties on sales of licensed products at percentages ranging from a high-single-digit to mid-teens, subject to certain customary reductions. In addition, under certain circumstances, in lieu of receiving the foregoing milestone payments and royalties, the Company may elect to receive a specified percentage of payments received by Gossamer and its stockholders (with some exclusions) in connection with Gossamer’s grant of a sublicense or other rights to the licensed products or if Gossamer undergoes a change of control and the value of the transaction exceeds a certain value (provided that Gossamer can prevent the Company from exercising this option if the parent company of Gossamer is the entity undergoing the change of control). Conversely, the Company could be required to accept such a specified percentage of those payments if Gossamer agrees to pay the Company a certain minimum upon Gossamer and its stockholders being paid. Such amount may be reduced if the subject transaction includes pharmaceutical candidates or products or other named asset categories in addition to the licensed products.

The Gossamer License expires on a licensed-product-by-licensed-product and country-by-country basis on the later of fifteen years from the date of first commercial sale or when there is no longer a valid patent claim covering such licensed product in such country. Either party may terminate the Gossamer License for an uncured material breach by the other party or upon the bankruptcy or insolvency of the other party. Gossamer may terminate the Gossamer License in the event Gossamer determines there is a potential safety or efficacy issue with the licensed products. The Company may terminate the Gossamer License if Gossamer institutes certain actions related to the licensed patents. Under certain termination circumstances, the Company would have worldwide rights to the terminated program.

As of December 31, 2018, all development milestones, sales-based milestones and royalty payments within the Gossamer License are constrained to the point where no transaction price has been allocated to the future milestones or royalty payments.