Condensed Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 4,785	$ 4,850	$ 15,761	$ 14,373
Change in fair value of derivative instruments:
Change in fair value of derivative instruments for the period	38	(259)	2,058	(904)
Income tax effect	(13)	90	(720)	316
Changes from derivative instruments	25	(169)	1,338	(588)
Change in securities available-for-sale:
Unrealized appreciation (depreciation) for the period	(959)	2,453	(15,566)	4,533
Reclassification adjustment for securities gains realized in income	6	2	374	2
Income tax effect	334	(860)	5,318	(1,588)
Unrealized gains (losses) on available-for-sale securities	(619)	1,595	(9,874)	2,947
Other Comprehensive Income (Loss), Net of Tax	(594)	1,426	(8,536)	2,359
Comprehensive Income	$ 4,191	$ 6,276	$ 7,225	$ 16,732