Summary of Estimated Fair Values of Bonds Held on Deposit (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Schedule Of Available For Sale Securities [Line Items]
Estimated Fair Value	$ 139,026	$ 148,118
On Deposit With Governmental Authorities
Schedule Of Available For Sale Securities [Line Items]
Estimated Fair Value	25,472	26,093
Held In Trust Pursuant To Third Party Requirements
Schedule Of Available For Sale Securities [Line Items]
Estimated Fair Value	112,367	119,513
Letter Of Credit Held For Third Party Requirements
Schedule Of Available For Sale Securities [Line Items]
Estimated Fair Value	$ 1,187	$ 2,512