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]
Operating lease, existence of option to extend	true
Finance lease, existence of option to extend	true
Rent expense	$ 0.2	$ 0.2	$ 0.2
Minimum [Member]
Commitments And Contingencies [Line Items]
Operating lease, remaining lease term	1 month
Finance lease, remaining lease term	1 month
Maximum [Member]
Commitments And Contingencies [Line Items]
Operating lease, remaining lease term	60 months
Finance lease, remaining lease term	60 months
Operating lease, options to extend lease term	5 years
Finance lease, options to extend lease term	5 years