Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

v3.20.2
Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)
$ in Thousands
Sep. 30, 2020
Dec. 31, 2019
Significant Accounting Policies [Line Items]    
Accumulated Deficit $ 1,043,274 $ 817,961
ASU 2016-13    
Significant Accounting Policies [Line Items]    
Change in Accounting Principle, Accounting Standards Update, Early Adoption [true false] true  
Change in Accounting Principle, Accounting Standards Update, Adoption Date Jan. 01, 2020  
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false] true  
ASU 2018-15    
Significant Accounting Policies [Line Items]    
Change in Accounting Principle, Accounting Standards Update, Early Adoption [true false] true  
Change in Accounting Principle, Accounting Standards Update, Adoption Date Jan. 01, 2020  
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false] true  
ASU 2019-12    
Significant Accounting Policies [Line Items]    
Change in Accounting Principle, Accounting Standards Update, Early Adoption [true false] true  
Change in Accounting Principle, Accounting Standards Update, Adoption Date Jan. 01, 2020  
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false] true