Fair Values of Assets and Liabilities - Losses Realized on Assets Measured on Non-Recurring Basis (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Fair Value Disclosures [Abstract]
Impaired loans	$ (382)	$ (3,020)	$ (843)	$ (2,739)
Other real estate owned	(1,126)	(728)	(1,154)	(1,078)
Total losses	$ (1,508)	$ (3,748)	$ (1,997)	$ (3,817)