Income Taxes - Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal	$ 126,358	$ 211,641	$ 209,454
State	37,038	37,006	38,095
Deferred:
Federal	138	60,785	(9,230)
State	(999)	(42)	(1,884)
Total	$ 162,535	$ 309,390	$ 236,435