Consolidated Statements of Shareholders' Equity (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, 2009	$ 24,995	$ 84,814	$ 49,463	$ 249	$ 159,521
Balance (in shares) at Dec. 31, 2009		15,298,000
Comprehensive income:
Net income	0	0	25,570	0	25,570
Other comprehensive income (loss), net				(56)	(56)
Preferred stock dividends and accretion	339	0	(1,659)	0	(1,320)
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)		23,000
Tax benefit associated with stock awards	0	8	0	0	8
Balance at Dec. 31, 2010	25,334	85,264	71,307	193	182,098
Balance (in shares) at Dec. 31, 2010		15,321,000
Comprehensive income:
Net income	0	0	15,952	0	15,952
Other comprehensive income (loss), net				2,956	2,956
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 dividends and accretion	1,046	0	(1,084)	0	(38)
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)		77,000
Tax benefit associated with stock awards	0	1	0	0	1
Balance at Dec. 31, 2011	0	84,564	83,107	3,149	170,820
Balance (in shares) at Dec. 31, 2011		15,398,000			15,398,197
Comprehensive income:
Net income	0	0	16,844	0	16,844
Other comprehensive income (loss), net				1,534	1,534
Cash dividends on common stock	0	0	(7,717)	0	(7,717)
Stock-based compensation expense	0	811	0	0	811
Issuance of common stock under stock plans	0	301	0	0	301
Issuance of common stock under stock plans (in shares)		86,000
Tax benefit associated with stock awards	0	31	0	0	31
Balance at Dec. 31, 2012	$ 0	$ 85,707	$ 92,234	$ 4,683	$ 182,624
Balance (in shares) at Dec. 31, 2012		15,484,000			15,483,598