Income Taxes - Schedule of Components of Income Tax Expense (Benefit) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current income taxes:
Federal taxes									$ 57,716	$ 31,401	$ 26,164
State and local taxes									6,768	7,977	6,513
Deferred income taxes:
Federal taxes									(32,962)	5,987	3,455
State and local taxes									114	1,087	(77)
Total	$ 17,455	$ 15,140	$ (2,247)	$ 1,288	$ 14,199	$ 15,902	$ 10,091	$ 6,260	$ 31,636	$ 46,452	$ 36,055