Accumulated Other Comprehensive Income - Summary of Accumulated Other Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Schedule Of Amounts In Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	$ 6,607	$ 7,296
Reclassification for gains included in net income	(112)
Current year changes	(332)	(783)
Ending balance	6,274	6,513
Unrealized Gain (Loss) on Derivatives [Member]
Schedule Of Amounts In Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(23)	856
Current year changes	208	(94)
Ending balance	185	762
Unrealized Gain (Loss) On Securities [Member]
Schedule Of Amounts In Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	6,630	6,440
Reclassification for gains included in net income	(112)
Current year changes	(429)	(689)
Ending balance	$ 6,089	$ 5,751