Premises and Equipment Net - Components of Premises and Equipment Included in Balance Sheets (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Premises and equipment	$ 24,651	$ 24,739
Less accumulated depreciation	(13,005)	(12,857)
Premises and equipment, net	11,646	11,882
Land and Improvements
Property, Plant and Equipment [Line Items]
Premises and equipment	2,350	2,004
Buildings and Improvements
Property, Plant and Equipment [Line Items]
Premises and equipment	12,232	13,032
Furniture and Equipment
Property, Plant and Equipment [Line Items]
Premises and equipment	$ 10,069	$ 9,703