Income Taxes - Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current:
Federal	$ 180,895	$ 148,221	$ 137,675
State	36,142	28,881	30,352
Deferred:
Federal	2,681	(4,451)	(13,402)
State	567	(735)	(2,406)
Total	$ 220,285	$ 171,916	$ 152,219