Income Tax - Income Tax Provision (Benefit) on Income From Operations (Detail) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Federal					$ 41,366	$ 44,841	$ 34,504
State					7,023	6,670	4,827
Current income tax expense benefit					48,389	51,511	39,331
Deferred					(28,939)	(7,956)	(3,804)
Income tax expense benefit	$ 9,200	$ 989	$ 5,188	$ 9,350	$ 19,450	$ 43,555	$ 35,527