CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Preferred Shares [Member]	Common Stock [Member]	Additional Paid-in-Capital [Member]	Accumulated Distributions in Excess of Net Income [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Non-controlling Interests [Member]
Balance at Dec. 31, 2009	$ 1,246,008	$ 327,867	$ 12	$ 1,750,979	$ (922,090)	$ 673	$ 88,567
Balance (in shares) at Dec. 31, 2009		11,455,200	121,943,258
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Contributions from noncontrolling interests	4,854						4,854
Redemption of noncontrolling OP units for common shares				2,685			(2,685)
Redemption of noncontrolling OP units for common shares (in shares)			457,351
Transfer of noncontrolling interests	(1,957)						(1,957)
Issuance of Convertible Notes				13,134
Forfeiture of employee performance common shares	171				171
Forfeiture of employee performance common shares (in shares)			(21,720)
Exercise of employee common share options	(356)			(356)
Exercise of employee common share options (in shares)			95,976
Issuance of common shares and deferred compensation amortization, net	171,503		3	171,500
Issuance of common shares and deferred compensation amortization, net (in shares)			24,077,724
Dividends/distributions	(90,267)				(81,911)		(8,356)
Net income (loss)	(37,410)				(32,960)		(4,450)
Other comprehensive income (loss)	(779)					(779)
Balance at Dec. 31, 2010	1,304,901	327,867	15	1,937,942	(1,036,790)	(106)	75,973
Balance (in shares) at Dec. 31, 2010		11,455,200	146,552,589
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Contributions from noncontrolling interests	2						2
Redemption of noncontrolling OP units for common shares				2,187			(2,187)
Redemption of noncontrolling OP units for common shares (in shares)			398,927
Repurchase of common shares	(31,916)			(31,916)
Repurchase of common shares (in shares)			(3,974,645)
Repurchase of preferred shares	(15,456)	(16,194)			738
Repurchase of preferred shares (in shares)		(544,126)
Obtained control of noncontrolling investment	574						574
Exercise of employee common share options	221			221
Exercise of employee common share options (in shares)			250,355
Forfeiture of employee common shares	69				69
Forfeiture of employee common shares (in shares)			(10,140)
Issuance of common shares and deferred compensation amortization, net	102,416			102,416
Issuance of common shares and deferred compensation amortization, net (in shares)			11,721,265
Dividends/distributions	(102,874)				(97,063)		(5,811)
Net income (loss)	(89,778)				(79,584)		(10,194)
Other comprehensive income (loss)	2,044					2,044
Balance at Dec. 31, 2011	1,170,203	311,673	15	2,010,850	(1,212,630)	1,938	58,357
Balance (in shares) at Dec. 31, 2011		10,911,074	154,938,351
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Contributions from noncontrolling interests	1,262						1,262
Redemption of noncontrolling OP units for common shares				1,343			(1,343)
Redemption of noncontrolling OP units for common shares (in shares)			257,427
Repurchase of preferred shares	(70,000)	(67,883)			(2,117)
Repurchase of preferred shares (in shares)		(2,775,674)
Issuance of common shares upon conversion of Convertible Notes	33,770		1	33,769
Issuance of common shares upon conversion of Convertible Notes (in shares)	4,487,060		4,487,060
Exercise of employee common share options, net	(534)			(534)
Exercise of employee common share options, net (in shares)			110,944
Issuance of common shares and deferred compensation amortization, net	167,523		2	167,521
Issuance of common shares and deferred compensation amortization, net (in shares)			18,822,882
Deconsolidation of consolidated joint venture	(782)						(782)
Dividends/distributions	(144,753)				(109,372)		(35,381)
Net income (loss)	184,638				180,316		4,322
Other comprehensive income (loss)	(8,162)					(8,162)
Balance at Dec. 31, 2012	$ 1,333,165	$ 243,790	$ 18	$ 2,212,949	$ (1,143,803)	$ (6,224)	$ 26,435
Balance (in shares) at Dec. 31, 2012		8,135,400	178,616,664