Condensed Consolidated Statements of Shareholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Preferred Stock [Member]	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Dec. 31, 2010	$ 179,801	$ 32,519	$ 150	$ (1,743)	$ 133,673	$ 15,775	$ (573)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	18,217	0	0	0	0	18,217	0
Change in fair value of available for sale securities, net of tax	6,302	0	0	0	0	0	6,302
Reclassification adjustment for realized gain on sale of securities included in net income, net of tax	(926)	0	0	0	0	0	(926)
Reclassification of cash flow hedge, net of tax	(85)	0	0	0	0	0	(85)
Total comprehensive income	23,508
Cash dividends paid on common shares, $0.1575 per share	(2,644)	0	0	0	0	(2,644)	0
Cash dividends paid on preferred stock	(1,313)	0	0	0	0	(1,313)	0
Preferred stock accretion of discount	0	575	0	0	0	(575)	0
Issuance under equity compensation plans, net	1,369	0	1	0	1,368	0	0
Issuance under public stock offering 2,743,900 shares	32,608	0	27	0	32,581	0	0
Share-based compensation	1,120	0	0	0	1,120	0	0
Excess tax benefit related to equity compensation plans	22	0	0	0	22	0	0
Balance at Sep. 30, 2011	234,471	33,094	178	(1,743)	168,764	29,460	4,718
Balance at Dec. 31, 2011	239,565	33,293	178	(1,743)	169,138	35,097	3,602
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	22,881	0	0	0	0	22,881	0
Change in fair value of available for sale securities, net of tax	6,526	0	0	0	0	0	6,526
Reclassification adjustment for realized gain on sale of securities included in net income, net of tax	(740)	0	0	0	0	0	(740)
Reclassification of cash flow hedge, net of tax	0
Total comprehensive income	28,667
Cash dividends paid on common shares, $0.1575 per share	(2,813)	0	0	0	0	(2,813)	0
Cash dividends paid on preferred stock	(1,312)	0	0	0	0	(1,312)	0
Preferred stock accretion of discount	0	621	0	0	0	(621)	0
Issuance under equity compensation plans, net	1,532	0	2	0	1,530	0	0
Share-based compensation	1,791	0	0	0	1,791	0	0
Excess tax benefit related to equity compensation plans	86	0	0	0	86	0	0
Balance at Sep. 30, 2012	$ 267,516	$ 33,914	$ 180	$ (1,743)	$ 172,545	$ 53,232	$ 9,388