Income Tax - Income Tax Provision (Benefit) on Income From Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Federal	$ 22,882	$ 41,366	$ 44,841
State	4,666	7,023	6,670
Current income tax expense benefit	27,548	48,389	51,511
Deferred	(29,865)	(28,939)	(7,956)
Income tax expense benefit	$ (2,317)	$ 19,450	$ 43,555