Changes to Accumulate Other Comprehensive Income by Components (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (600)	$ 1,397
Unrealized gain (loss) arising during the period	806	100
Reclassification adjustment from other comprehensive income	(507)	(308)
Tax effect of current period changes
Total changes, net of taxes	299	(208)
Ending balance	(301)	1,189
Unrealized Gain (Losses) on AFS Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(826)	1,397
Unrealized gain (loss) arising during the period	1,023	100
Reclassification adjustment from other comprehensive income	(507)	(308)
Tax effect of current period changes
Total changes, net of taxes	516	(208)
Ending balance	(310)	1,189
Cash Flow Hedge
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	226
Unrealized gain (loss) arising during the period	(217)
Tax effect of current period changes
Total changes, net of taxes	(217)
Ending balance	$ 9