Fair Values of Assets and Liabilities - Losses Realized on Assets Measured on Non-Recurring Basis (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Fair Value Disclosures [Abstract]
Impaired loans	$ (2,838)	$ 456	$ (3,532)	$ (1,291)
Other real estate owned	(78)	(51)	(1,205)	(1,109)
Total losses	$ (2,916)	$ 405	$ (4,737)	$ (2,400)