Interim Condensed Consolidated Statements of Stockholders' Equity (Unaudited) (USD $) In Thousands, except Share data	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance at Dec. 31, 2010	$ 170,548	$ 136	$ 128,061	$ 226,114	$ 36,287	$ 561,146
Balance (in Shares) at Dec. 31, 2010	10,840,608	13,637,258
Net income				18,724		18,724
Other comprehensive income					3,439	3,439
Stock-based compensation			984			984
Tax benefit from exercise of stock options			305			305
Shares of Stock Issued from Stock Option Exercise (in Shares)		167,134
Value of Stock Issued from Stock Option Exercise		2	5,951			5,953
Shares issued in conversion of preferred stock to common stock	(7)		7
Shares issued in conversion of preferred stock to common stock (in Shares)	(468)	113
Dividends declared to preferred stockholders				(2,168)		(2,168)
Dividends declared to common stockholders				(3,865)		(3,865)
Balance at Mar. 31, 2011	170,541	138	135,308	238,805	39,726	584,518
Balance (in Shares) at Mar. 31, 2011	10,840,140	13,804,505
Balance at Dec. 31, 2011	170,515	138	139,183	265,198	36,702	611,736
Balance (in Shares) at Dec. 31, 2011	10,838,490	13,862,738
Net income				12,676		12,676
Other comprehensive income					4,859	4,859
Stock-based compensation			543			543
Tax benefit from exercise of stock options			3			3
Shares of Stock Issued from Stock Option Exercise (in Shares)		120,050
Value of Stock Issued from Stock Option Exercise		1	5,577			5,578
Dividends declared to preferred stockholders				(2,168)		(2,168)
Dividends declared to common stockholders				(4,195)		(4,195)
Balance at Mar. 31, 2012	$ 170,515	$ 139	$ 145,306	$ 271,511	$ 41,561	$ 629,032
Balance (in Shares) at Mar. 31, 2012	10,838,490	13,982,788