Condensed Financial Information (Parent Company Only) - Condensed Statements of Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Scheduleof Condensed Statementof Comprehensive Income [Line Items]
Net income	$ 4,115	$ 4,785	$ 5,665	$ 5,311	$ 5,170	$ 4,850	$ 4,910	$ 4,613	$ 19,876	$ 19,543	$ 12,797
Other Comprehensive Income (Loss)
Change in fair value of derivative instruments, net of taxes									1,734	(376)	(2,300)
Less: reclassification adjustment for realized gains included in net income, net of taxes									(374)	(2)	(1,777)
Other Comprehensive Income									(10,830)	1,259	5,494
Comprehensive Income									9,046	20,802	18,291
Parent Company [Member]
Scheduleof Condensed Statementof Comprehensive Income [Line Items]
Net income									19,876	19,543	12,797
Other Comprehensive Income (Loss)
Change in fair value of derivative instruments, net of taxes									1,734	(376)	(2,300)
Unrealized appreciation (depreciation) on available-for-sale securities, net of taxes									(12,320)	1,636	8,949
Less: reclassification adjustment for realized gains included in net income, net of taxes									(244)	1	1,155
Other Comprehensive Income									(10,830)	1,259	5,494
Comprehensive Income									$ 9,046	$ 20,802	$ 18,291