Income Taxes - Income Tax Provision (Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current income tax provision:
Federal	$ 33,578	$ 41,177	$ 26,752
State	7,674	5,420	2,798
Total	41,252	46,597	29,550
Deferred income tax provision:
Federal	988	1,177	5,217
State	49	(983)	216
Total	1,037	194	5,433
Total income tax provision	$ 42,289	$ 46,791	$ 34,983