Income Taxes - Summary of Income Tax Provision (Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current:
U.S. federal	$ 20,768	$ 18,085	$ 9,924
State	1,759	1,690	2,496
Total current income tax provision	22,527	19,775	12,420
Deferred:
U.S. federal	8,570	9,547	11,822
State	(150)	(85)	276
Total deferred income tax provision	8,420	9,462	12,098
Total income tax provision	$ 30,947	$ 29,237	$ 24,518