Income Taxes - Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current:
Federal	$ 209,454	$ 180,895	$ 148,221
State	38,095	36,142	28,881
Deferred:
Federal	(9,230)	2,681	(4,451)
State	(1,884)	567	(735)
Total	$ 236,435	$ 220,285	$ 171,916