Income Taxes - Current and Deferred 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:
Federal									$ 27,143	$ 22,427	$ 41,578
State									11,389	10,354	2,493
Total current									38,532	32,781	44,071
Deferred:
Federal									(5,908)	1,650	(17,302)
State									(2,021)	24	(1,239)
Total deferred									(7,929)	1,674	(18,541)
Income tax expense (benefit)	$ 12,346	$ 9,285	$ 3,715	$ 5,257	$ 8,026	$ 9,938	$ 8,802	$ 7,689	$ 30,603	$ 34,455	$ 25,530