Income Taxes - Components of Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current
Federal	$ 12,790	$ 28,077	$ 31,787
State	1,855	2,539	3,168
Total current tax expense	14,645	30,616	34,955
Deferred
Federal	5,489	4,339	3,200
State	910	2,017	1,194
Total deferred tax expense	6,399	6,356	4,394
Income tax expense	$ 21,044	$ 36,972	$ 39,349