Annual report pursuant to Section 13 and 15(d)

Commitments and Contingencies - License Agreements (Details)

v3.8.0.1
Commitments and Contingencies - License Agreements (Details) - USD ($)
$ in Millions
 1 Months Ended 12 Months Ended
Sep. 30, 2016
May 31, 2016
Sep. 30, 2015
Apr. 30, 2013
Dec. 31, 2017
Dec. 31, 2016
Feb. 28, 2013
Common Stock              
License Agreements              
Shares issued         2,592,591 4,600,000  
Dana Farber              
License Agreements              
Payments due when the Company achieves certain milestones per the license agreement             $ 3.4
Amount of futue 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 futue potential milestone payments accrued as of the end of the reporting period         0.0 0.0  
Amount paid for annual license maintenance fees and research services         0.9 1.0  
Accounts payable and accrued expenses         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         $ 0.4 $ 0.0