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Property and Equipment - Additional Information (Detail) - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Property Plant And Equipment [Abstract]        
Depreciation and amortization expense $ 371,000 $ 405,000 $ 1,200,000 $ 1,100,000