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Employee Benefit Plans - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Expense for matching contributions $ 0.2 $ 0.3 $ 2.5 $ 2.9  
ESPP offering period     6 months 6 months  
Employee Stock [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Maximum employee subscription rate         15.00%
Purchase price of common stock shares, lower of fair market value, percentage       85.00%  
Shares of common stock issued 0 0 52,733 119,393  
Shares available for future purchase 1,424,355   1,424,355