Consolidated Statements of Shareholders' Equity (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Stock Issued During Period, Value, Conversion of Convertible Securities			$ 0
Stock Issued During Period, Value, New Issues	179,686	95,424	117,070
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	1,723	1,198	60
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	(411)	(142)	(128)
Cumulative Effect of Prospective Application of New Accounting Principle			12
Stock Repurchased and Retired During Period, Value	(921)
Net Income	74,042	39,812	29,472
Dividends, Preferred Stock, Cash	(2,036)		(3,061)
Dividends, Common Stock, Cash	(62,488)	(43,988)	(19,817)
Other Comprehensive Income (Loss), Net of Tax	55,766	(13,312)	(4)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	616,710	371,349	292,357	168,753
Series D Preferred Stock [Member]
Stock Issued During Period, Value, Conversion of Convertible Securities			(41,749)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest				41,749
Series A Preferred Stock [Member]
Stock Issued During Period, Value, New Issues	55,689
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	(282)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	55,407
Common Stock [Member]
Stock Issued During Period, Shares, Conversion of Convertible Securities			42
Stock Issued During Period, Value, New Issues	138	97	122
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	2	4
Stock Repurchased and Retired During Period, Value	(1)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	543	404	303	139
Additional Paid-in Capital [Member]
Stock Issued During Period, Shares, Conversion of Convertible Securities			41,707
Stock Issued During Period, Value, New Issues	123,859	95,327	116,948
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	1,721	1,194	60
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	(129)	(142)	(128)
Stock Repurchased and Retired During Period, Value	(920)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	759,214	634,683	538,304	379,717
Accumulated Other Comprehensive Income (Loss) [Member]
Other Comprehensive Income (Loss), Net of Tax	55,766	(13,312)	(4)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	52,511	(3,255)	10,057	10,061
Accumulated Distributions in Excess of Net Income [Member]
Cumulative Effect of Prospective Application of New Accounting Principle			12
Net Income		39,812	29,472
Dividends, Preferred Stock, Cash	(2,036)		(3,061)
Dividends, Common Stock, Cash	(62,488)	(43,988)	(19,817)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ (250,965)	$ (260,483)	$ (256,307)	$ (262,913)