Consolidated Statements of Changes in Shareholders' Equity and Comprehensive Income (USD $) In Thousands, except Share data, unless otherwise specified	Preferred stock [Member]	Common stock [Member]	Retained earnings [Member]	Accumulated other comprehensive income [Member]	Total
Balance at Dec. 31, 2008	$ 0	$ 33,701	$ 46,567	$ 292	$ 80,560
Balance (in shares) at Dec. 31, 2008		9,510
Comprehensive income:
Net income	0	0	6,214	0	6,214
Net change in unrealized gain (net of tax expense)	0	0	0	(43)	(43)
Total comprehensive income					6,171
Issuance of preferred stock to U.S. Treasury	24,660	0	0	0	24,660
Issuance of warrant to U.S. Treasury	0	1,720	0	0	1,720
Issuance of common stock, net of offering costs	0	48,991	0	0	48,991
Issuance of common stock, net of offering costs (in shares)		5,750
Preferred stock dividends and accretion	335	0	(1,600)	0	(1,265)
Cash dividends on common stock	0	0	(1,718)	0	(1,718)
Cash dividends on common stock	0	0	(1,718)	0	(1,718)
Stock-based compensation expense	0	306	0	0	306
Issuance of common stock under stock plans	0	90	0	0	90
Issuance of common stock under stock plans (in shares)		39
Tax benefit associated with stock awards	0	6	0	0	6
Cancellation of restricted stock	0	0	0	0	0
Cancellation of restricted stock (in shares)		(1)
Preferred stock dividends and accretion	335	0	(1,600)	0	(1,265)
Balance at Dec. 31, 2009	24,995	84,814	49,463	249	159,521
Balance (in shares) at Dec. 31, 2009		15,298
Comprehensive income:
Net income	0	0	25,570	0	25,570
Net change in unrealized gain (net of tax expense)	0	0	0	(508)	(508)
Total comprehensive income					25,062
Preferred stock dividends and accretion	339	0	(1,659)	0	(1,320)
Cash dividends on common stock	0	0	(2,067)	0	(2,067)
Cash dividends on common stock	0	0	(2,067)	0	(2,067)
Stock-based compensation expense	0	338	0	0	338
Issuance of common stock under stock plans	0	104	0	0	104
Issuance of common stock under stock plans (in shares)		23
Tax benefit associated with stock awards	0	8	0	0	8
Preferred stock dividends and accretion	339	0	(1,659)	0	(1,320)
Balance at Dec. 31, 2010	25,334	85,264	71,307	(259)	181,646
Balance (in shares) at Dec. 31, 2010		15,321			15,321,227
Comprehensive income:
Net income	0	0	15,952	0	15,952
Net change in unrealized gain (net of tax expense)	0	0	0	3,339	3,339
Total comprehensive income					19,291
Preferred stock dividends and accretion	1,046	0	(1,084)	0	(38)
Cash dividends on common stock	0	0	(3,068)	0	(3,068)
Cash dividends on common stock	0	0	(3,068)	0	(3,068)
Stock-based compensation expense	0	623	0	0	623
Issuance of common stock under stock plans	0	301	0	0	301
Issuance of common stock under stock plans (in shares)		77
Tax benefit associated with stock awards	0	1	0	0	1
Preferred stock dividends and accretion	1,046	0	(1,084)	0	(38)
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)
Balance at Dec. 31, 2011	$ 0	$ 84,564	$ 83,107	$ 3,080	$ 170,751
Balance (in shares) at Dec. 31, 2011		15,398			15,398,197