Consolidated Statements of Stockholders’ Equity (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
Comprehensive income
Net income				5,066	5,066
Change in unrealized appreciation on available-for-sale securities, net of income taxes			(95)		(95)
Comprehensive income					4,971
Stock issued as bonus shares					0
Vesting bonus shares		230			230
Stock issued for employee stock purchase plan		127			127
Exercise of stock options		97			97
Stock granted under stock-based compensation plans		43			43
Dividends paid				(3,292)	(3,292)
Balance, at Mar. 31, 2011	173	114,537	417	284,420	399,547
Comprehensive income
Net income				20,308	20,308
Change in unrealized appreciation on available-for-sale securities, net of income taxes			22		22
Comprehensive income					20,330
Stock issued as bonus shares		98			98
Vesting bonus shares		836			836
Exercise of stock options		288			288
Stock granted under stock-based compensation plans		95			95
Securities exchanged under stock option plan – (5,252 shares)		(136)			(136)
Repurchase of common stock	(1)	(3,282)			(3,283)
Dividends paid				(9,864)	(9,864)
Balance, at Dec. 31, 2011	172	112,436	439	294,864	407,911
Comprehensive income
Net income				6,355	6,355
Change in unrealized appreciation on available-for-sale securities, net of income taxes			(51)		(51)
Comprehensive income					6,304
Stock issued as bonus shares		58			58
Vesting bonus shares		372			372
Stock issued for employee stock purchase plan		132			132
Stock granted under stock-based compensation plans		30			30
Repurchase of common stock		(2,052)			(2,052)
Dividends paid				(3,443)	(3,443)
Balance, at Mar. 31, 2012	$ 172	$ 110,976	$ 388	$ 297,776	$ 409,312