Income Tax - Income Tax Provision (Benefit) on Income From Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Federal	$ 44,841	$ 34,504	$ 25,625
State	6,670	4,827	2,590
Current income tax expense benefit	51,511	39,331	28,215
Deferred	(7,956)	(3,804)	(1,497)
Income tax expense benefit	$ 43,555	$ 35,527	$ 26,718