Other Comprehensive Income (Loss) - Summary of Reclassification Out of Each Component of Accumulated Comprehensive Income (Loss) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income On Derivatives [Line Items]
Net gains on securities available for sale	$ 11	$ 3
Tax expense	(1,815)	(156)
Net income	3,686	2,094
Amount Reclassified From Accumulated Other Comprehensive Income [Member] | Realized Net Gains on Sale of Available for Sale Securities [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income On Derivatives [Line Items]
Net gains on securities available for sale	(11)	(3)
Tax expense	4
Net income	$ (7)	$ (3)