Mortgage Banking Activities - Valuation Allowance for Mortgage Servicing Rights (Detail) (USD $)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Mortgage Banking [Abstract]
Balance, beginning of year	$ (680,000)	$ (680,000)
Impairment charges	(6,000)
Recoveries	2,000	676,000
Balance, end of period	$ (4,000)	$ (4,000)