Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Commitments And Contingencies [Line Items]
Lessee operating lease, expiration year	2030
Rent expense	$ 8.7	$ 7.6	$ 6.7
Office Equipment
Commitments And Contingencies [Line Items]
Lessee operating lease, expiration year	2024