Fair Values of Assets and Liabilities - Losses Realized on Assets Measured on Non-Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Fair Value Disclosures [Abstract]
Impaired loans	$ 456	$ (1,468)	$ (1,291)	$ (13,063)
Other real estate owned	(51)	(90)	(1,109)	(188)
Total losses	$ 405	$ (1,558)	$ (2,400)	$ (13,251)