Consolidated Statements of Stockholders' Equity (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 January 1, 2011 at Dec. 31, 2010	$ 170,548	$ 136	$ 128,061	$ 220,329	$ 36,287	$ 555,361
Balance at January 1, 2011 (in Shares) at Dec. 31, 2010	10,840,608	13,637,258
Net income				64,990		64,990
Other comprehensive income (loss)					415	415
Stock-based compensation			2,751			2,751
Tax expense from exercise of stock options			(52)			(52)
Shares sold – options exercised		2	8,390			8,392
Shares sold – options exercised (in Shares)		224,969				(224,969)
Shares issued in conversion of preferred stock to common stock	(33)		33
Shares issued in conversion of preferred stock to common stock (in Shares)	(2,118)	511
Dividends declared to preferred stockholders				(8,671)		(8,671)
Dividends declared to common stockholders				(16,317)		(16,317)
Balance at Dec. 31, 2011	170,515	138	139,183	260,331	36,702	606,869
Balance (in Shares) at Dec. 31, 2011	10,838,490	13,862,738
Net income				59,300		59,300
Other comprehensive income (loss)					14,106	14,106
Stock-based compensation			2,366			2,366
Tax expense from exercise of stock options			(267)			(267)
Shares sold – options exercised		3	13,409			13,412
Shares sold – options exercised (in Shares)		295,371				(295,371)
Shares issued in conversion of preferred stock to common stock	(1)		1
Shares issued in conversion of preferred stock to common stock (in Shares)	(78)	18
Dividends declared to preferred stockholders				(8,671)		(8,671)
Dividends declared to common stockholders				(30,967)		(30,967)
Balance at Dec. 31, 2012	170,514	141	154,692	279,993	50,808	656,148
Balance (in Shares) at Dec. 31, 2012	10,838,412	14,158,127
Net income				64,613		64,613
Other comprehensive income (loss)					(4,623)	(4,623)
Stock-based compensation			2,298			2,298
Tax expense from exercise of stock options			(225)			(225)
Shares sold – options exercised			991			991
Shares sold – options exercised (in Shares)		19,722				(21,522)
Shares issued in conversion of preferred stock to common stock	(4)		4
Shares issued in conversion of preferred stock to common stock (in Shares)	(747)	179
Dividends declared to preferred stockholders				(8,671)		(8,671)
Dividends declared to common stockholders				(17,719)		(17,719)
Repurchase of common shares		(1)	(4,699)			(4,700)
Repurchase of common shares (in Shares)		(100,000)
Balance at Dec. 31, 2013	$ 170,510	$ 140	$ 153,061	$ 318,216	$ 46,185	$ 688,112
Balance (in Shares) at Dec. 31, 2013	10,837,665	14,078,028