CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY AND COMPREHENSIVE INCOME (USD $) In Thousands, except Share data, unless otherwise specified	Total	Preferred Shares Series B	Preferred Shares Series C	Cumulative Preferred Distributions	Common Shares	Cumulative Common Distributions	Additional Paid in Capital	Cumulative Net Income	Cumulative Other Comprehensive Income (Loss)	Comprehensive Income
Balance at Dec. 31, 2008	$ 2,628,427	$ 83,306	$ 306,833	$ (123,641)	$ 940	$ (2,560,148)	$ 3,093,827	$ 1,827,821	$ (511)
Balance (in shares) at Dec. 31, 2008		3,450,000	12,700,000		93,991,635
Comprehensive income:
Net income	193,341							193,341		193,341
Unrealized gain (loss) on investments	3,741								3,741	3,741
Total comprehensive income	197,082									197,082
Issuance of shares, net	373,054				293		372,761
Issuance of shares, net (in shares)					29,325,000
Common share grants	624				1		623
Common share grants (in shares)					63,700
Repurchase of convertible senior notes	(5,002)						(5,002)
Distributions	(102,254)			(29,880)		(72,374)
Balance at Dec. 31, 2009	3,091,931	83,306	306,833	(153,521)	1,234	(2,632,522)	3,462,209	2,021,162	3,230
Balance (in shares) at Dec. 31, 2009		3,450,000	12,700,000		123,380,335
Comprehensive income:
Net income	21,351							21,351		21,351
Unrealized gain (loss) on investments	(999)								(999)	(999)
Total comprehensive income	20,352									20,352
Common share grants	1,018						1,018
Common share grants (in shares)					63,900
Repurchase of convertible senior notes	(1,058)						(1,058)
Distributions	(252,002)			(29,880)		(222,122)
Balance at Dec. 31, 2010	2,860,241	83,306	306,833	(183,401)	1,234	(2,854,644)	3,462,169	2,042,513	2,231
Balance (in shares) at Dec. 31, 2010		3,450,000	12,700,000		123,444,235
Comprehensive income:
Net income	190,440							190,440		190,440
Unrealized gain (loss) on investments	(626)								(626)	(626)
Total comprehensive income	189,814									189,814
Common share grants	1,366				1		1,365
Common share grants (in shares)					77,300
Distributions	(252,119)			(29,880)		(222,239)
Balance at Dec. 31, 2011	$ 2,799,302	$ 83,306	$ 306,833	$ (213,281)	$ 1,235	$ (3,076,883)	$ 3,463,534	$ 2,232,953	$ 1,605
Balance (in shares) at Dec. 31, 2011		3,450,000	12,700,000		123,521,535