Premises and Equipment - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Property, Plant and Equipment [Abstract]
Depreciation expense for premises and equipment	$ 1,063,000	$ 1,014,000	$ 3,227,000	$ 2,489,000