v3.8.0.1
Collaboration Agreements - Summary of Collaboration Revenue (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2017
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                      
Total revenue $ 9,799 $ 11,358 $ 11,346 $ 10,508 $ 22,648 $ 8,985 $ 6,978 $ 31,281 $ 43,011 $ 69,892 $ 59,119
Collaborative arrangement, product                      
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                      
Total revenue                 38,120 43,530 57,043
Program Licenses | July 2014 modification | Ivosidenib agreement                      
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                      
Total revenue                 0 0 15,808
Program Licenses | April 2015 modification (supplants undelivered elements of July 2014 modification) | AG-881 program licenses                      
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                      
Total revenue                 0 1,356 11,968
On-Going Development Services (Principal) | July 2014 modification | Collaborative arrangement, product                      
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                      
Total revenue                 0 0 14,711
On-Going Development Services (Principal) | April 2015 modification (supplants undelivered elements of July 2014 modification) | Collaborative arrangement, product                      
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                      
Total revenue                 0 1,656 1,719
On-Going Development Services (Principal) | May 2016 modification (supplants undelivered elements of April 2015 modification) | Collaborative arrangement, product                      
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                      
Total revenue                 11,827 21,308 0
On-Going Research and Development | July 2014 modification | Collaborative arrangement, product                      
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                      
Total revenue                 0 0 4,992
On-Going Research and Development | April 2015 modification (supplants undelivered elements of July 2014 modification) | Collaborative arrangement, product                      
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                      
Total revenue                 0 4,584 7,644
On-Going Research and Development | May 2016 modification (supplants undelivered elements of April 2015 modification) | Collaborative arrangement, product                      
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                      
Total revenue                 26,126 14,445 0
Committee Participations | July 2014 modification | Collaborative arrangement, product                      
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                      
Total revenue                 0 0 80
Committee Participations | April 2015 modification (supplants undelivered elements of July 2014 modification) | Collaborative arrangement, product                      
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                      
Total revenue                 0 89 121
Committee Participations | May 2016 modification (supplants undelivered elements of April 2015 modification) | Collaborative arrangement, product                      
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]                      
Total revenue                 $ 167 $ 92 $ 0