Consolidated Statements of Stockholders’ Equity (September 30, 2012 Unaudited) (USD $) In Thousands, unless otherwise specified	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Total
Balance at Dec. 31, 2010	$ 173	$ 114,040	$ 512	$ 282,646	$ 397,371
Change in unrealized appreciation on available-for-sale securities, net of income taxes			118		118
Comprehensive income					19,187
Stock issued as bonus shares		98			98
Vesting bonus shares		813			813
Stock issued for employee stock purchase plan		127			127
Exercise of stock options		358			358
Stock granted under stock-based compensation plans		108			108
Securities exchanged under stock option plan		(109)			(109)
Repurchase of common stock		(409)			(409)
Cash Dividends				(9,885)	(9,885)
Comprehensive income
Net income				19,069	19,069
Balance at Sep. 30, 2011	173	115,026	630	291,830	407,659
Change in unrealized appreciation on available-for-sale securities, net of income taxes			(191)		(191)
Comprehensive income					6,114
Vesting bonus shares		253			253
Exercise of stock options		27			27
Stock granted under stock-based compensation plans		30			30
Securities exchanged under stock option plan		(27)			(27)
Repurchase of common stock	(1)	(2,873)			(2,874)
Cash Dividends				(3,271)	(3,271)
Comprehensive income
Net income				6,305	6,305
Balance at Dec. 31, 2011	172	112,436	439	294,864	407,911
Change in unrealized appreciation on available-for-sale securities, net of income taxes			143		143
Comprehensive income					19,794
Stock issued as bonus shares	1	191			192
Vesting bonus shares		998			998
Stock issued for employee stock purchase plan		132			132
Stock granted under stock-based compensation plans		67			67
Repurchase of common stock	(6)	(14,668)			(14,674)
Cash Dividends				(10,172)	(10,172)
Comprehensive income
Net income				19,651	19,651
Balance at Sep. 30, 2012	$ 167	$ 99,156	$ 582	$ 304,343	$ 404,248