Income Taxes - Components of Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current
Federal	$ 28,077	$ 31,787	$ 10,395
State	2,539	3,168	1,787
Total current tax expense	30,616	34,955	12,182
Deferred
Federal	4,339	3,200	29,933
State	2,017	1,194	2,663
Total deferred tax expense	6,356	4,394	32,596
Income tax expense	$ 36,972	$ 39,349	$ 44,778