Premises and Equipment - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Property, Plant and Equipment [Abstract]
Depreciation expense for premises and equipment	$ 1,268,000	$ 1,180,000	$ 3,849,000	$ 3,228,000