Income Taxes - Summary of Reconciliation of Statutory Federal Tax and Effective Income Tax Rates (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Effective Income Tax Rates Continuing Operations
Federal income tax expense (1)	[1]	$ 22,759	$ 23,865	$ 21,121
State income taxes, net of federal benefit		3,422	3,062	2,946
ESOP dividend deduction		(264)	(263)	(267)
Other		2,424	241	145
Total Income Tax Expense		$ 28,341	$ 26,905	$ 23,945
Effective Income Tax Rate		38.81%	39.54%	39.88%

[1] Federal income taxes were calculated at 35% for each year represented.