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Financial Instruments with Concentrations of Credit Risk - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]      
Allowance for doubtful accounts receivable $ 0.2 $ 0.2  
Government Contracts Concentration Risk | Sales Revenue, Net      
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]      
Concentration risk percentage 77.00% 77.00% 79.00%
Government Contracts Concentration Risk | Accounts Receivable      
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]      
Concentration risk percentage 83.00% 67.00%