Income Tax - Reconciliation of Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Currently payable
Federal	$ 5,270	$ 4,710	$ 3,900
State	241	(149)	(88)
Deferred	1,721	1,594	3,236
Total income tax expense	7,232	6,155	7,048
Reconciliation of federal statutory to actual tax expense
Federal statutory income tax at 35%	9,724	8,488	9,424
Tax exempt interest	(1,708)	(1,628)	(1,517)
Tax exempt income	(488)	(366)	(362)
Other tax exempt income	(199)	(309)	(342)
Nondeductible and other	(97)	(30)	(176)
Effect of state income taxes			21
Total income tax expense	$ 7,232	$ 6,155	$ 7,048