Accumulated Other Comprehensive Income (Loss) - Reclassification of Unrealized Losses and Impairments on Securities (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net gains (losses) on sale of securities available-for-securities	$ 6	$ (16)	$ 2	$ (17)
Tax (expense) benefit	(56)	(27)	(152)	(204)
Holding gains (losses) on securities | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net gains (losses) on sale of securities available-for-securities	6	(16)	2	(17)
Tax (expense) benefit	(2)	6	(1)	6
Impact on net income	$ 4	$ (10)	$ 1	$ (11)