Income Taxes - Income Tax Provision (Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current income tax provision:
Federal	$ 26,752	$ 25,105	$ 18,722
State	2,798	2,560	3,131
Total	29,550	27,665	21,853
Deferred income tax provision:
Federal	5,217	987	3,118
State	216	37	456
Total	5,433	1,024	3,574
Total income tax provision	$ 34,983	$ 28,689	$ 25,427