Employee Benefit Plans - Additional Information (Detail) - Subsidiary Issuer [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, expenses recognized	$ 8,615	$ 7,944	$ 6,454
Minimum [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution of employees contribution	11.00%
Employer matching contribution of employees gross pay	5.00%
Maximum [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution of employees contribution	100.00%
Employer matching contribution of employees gross pay	6.00%