Income Taxes - Summary of Income Tax Provision (Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current:
U.S. federal	$ 12,127	$ 20,768	$ 18,085
State	1,988	1,759	1,690
Total current income tax provision	14,115	22,527	19,775
Deferred:
U.S. federal	12,599	8,570	9,547
State	181	(150)	(85)
Total deferred income tax provision	12,780	8,420	9,462
Total income tax provision	$ 26,895	$ 30,947	$ 29,237