Condensed Consolidated Statements of Shareholders' Equity and Comprehensive Income (unaudited) (USD $) In Thousands, except Share data	Preferred stock [Member]	Common stock [Member]	Retained earnings [Member]	Accumulated other comprehensive income [Member]	Total
Balance at Dec. 31, 2009	$ 24,995	$ 84,814	$ 49,463	$ 249	$ 159,521
Balance (shares) at Dec. 31, 2009		15,298,000
Comprehensive income:
Net income	0	0	21,861	0	21,861
Net change in unrealized gain (net of tax expense)	0	0	0	1,940	1,940
Total comprehensive income					23,801
Preferred stock dividend and accretion	254	0	(1,244)	0	(990)
Cash dividends on common stock	0	0	(1,299)	0	(1,299)
Stock-based compensation expense	0	281	0	0	281
Issuance of common stock under stock plans (shares)		13,000
Issuance of common stock under stock plans	0	20	0	0	20
Tax benefit associated with stock awards	0	8	0	0	8
Balance at Sep. 30, 2010	25,249	85,123	68,781	2,189	181,342
Balance (shares) at Sep. 30, 2010		15,311,000
Balance at Dec. 31, 2010	25,334	85,264	71,307	(259)	181,646
Balance (shares) at Dec. 31, 2010		15,321,000			15,321,227
Comprehensive income:
Net income	0	0	11,713	0	11,713
Net change in unrealized gain (net of tax expense)	0	0	0	3,165	3,165
Total comprehensive income					14,878
Redemption of preferred stock issued to U.S. Treasury	(26,380)	0	0	0	(26,380)
Repurchase of warrant issued to U.S. Treasury	0	(1,625)	0	0	(1,625)
Preferred stock dividend and accretion	1,046	0	(1,084)	0	(38)
Cash dividends on common stock	0	0	(2,300)	0	(2,300)
Stock-based compensation expense	0	453	0	0	453
Issuance of common stock under stock plans (shares)		36,000
Issuance of common stock under stock plans	0	113	0	0	113
Tax benefit associated with stock awards	0		0	0	4
Balance at Sep. 30, 2011	$ 0	$ 84,209	$ 79,636	$ 2,906	$ 166,751
Balance (shares) at Sep. 30, 2011		15,357,000			15,357,466