Quarterly report pursuant to Section 13 or 15(d)

Commitments and Contingencies - License Agreements (Details)

v3.8.0.1
Commitments and Contingencies - License Agreements (Details) - USD ($)
$ in Millions
 1 Months Ended 3 Months Ended
Sep. 30, 2016
May 31, 2016
Sep. 30, 2015
Apr. 30, 2013
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Feb. 28, 2013
Dana Farber                
License Agreements                
Payments due when the Company achieves certain milestones per the license agreement               $ 3.4
Amount of future potential milestone payments accrued as of the end of the reporting period         $ 0.0   $ 0.0  
Whitehead                
License Agreements                
Payments due when the Company achieves certain milestones per the license agreement       $ 3.6        
Amount of future potential milestone payments accrued as of the end of the reporting period         0.0      
Amount paid for annual license maintenance fees and research services         0.1 $ 0.2    
Accounts payable and accrued expenses         0.3      
Fee included in accounts payable and accrued expenses as result of entry into the Collaboration Agreement with Incyte         0.2      
Whitehead | Common Stock                
License Agreements                
Shares issued       171,674        
TMRC                
License Agreements                
Up-front license fee     $ 1.0          
Payment of up-front license fee   $ 0.5 0.5          
Payments per indication due upon the successful achievement of clinical and regulatory milestones     $ 13.0          
Payments made upon achievement of development milestone $ 1.0              
Payments made under the supply management agreement         $ 0.0 $ 0.4