Annual report pursuant to Section 13 and 15(d)

Commitments and Contingencies - Additional Information (Details)

v3.8.0.1
Commitments and Contingencies - Additional Information (Details)
1 Months Ended 12 Months Ended
Dec. 31, 2017
USD ($)
RenewalOption
Nov. 21, 2017
USD ($)
Facility
Sep. 30, 2017
USD ($)
Dec. 31, 2017
USD ($)
RenewalOption
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Commitments And Contingencies [Line Items]            
Estimate of milestone payments $ 15,500,000     $ 15,500,000    
Operating leases, expiry date       2023-04    
Operating leases, number of successive renewal options | RenewalOption 2     2    
Operating leases, extended lease term       5 years    
Lease agreement term     63 months      
Lease commencement date     Nov. 14, 2017      
Total lease payments $ 18,946,000   $ 900,000 $ 18,946,000    
Lease payments term     2023-02      
Operating leases, total rental expense       $ 2,400,000 $ 3,800,000 $ 3,700,000
Operating leases, number of portions of leased facilities | Facility   1        
Operating leases, number of leased facilities | Facility   3        
Operating leases, sublease commencement date   Dec. 26, 2017        
Operating leases sublease income receivable   $ 5,100,000        
Operating leases sublease expiry date   2023-04        
Sublease tenant improvement allowance   $ 800,000        
Standby Letter of Credit [Member]            
Commitments And Contingencies [Line Items]            
Letter of credit amount   $ 1,000,000        
Funds drawn from letter of credit $ 0