CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (Unaudited) (USD $) In Thousands, unless otherwise specified	Total	Preferred Shares [Member]	Common Shares [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, 2011	$ 1,170,203	$ 311,673	$ 15	$ 2,010,850	$ (1,212,630)	$ 1,938	$ 58,357
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redemption of noncontrolling OP units for common shares	0	0	0	353	0	0	(353)
Repurchase Of Preferred Shares	(70,000)	(67,883)	0	0	(2,117)	0	0
Issuance of common shares and deferred compensation amortization, net	6,361	0	1	6,360	0	0	0
Contributions from noncontrolling interests	889	0	0	0	0	0	889
Dividends/distributions	(83,698)	0	0	0	(50,164)	0	(33,534)
Net income	11,104	0	0	0	8,121	0	2,983
Other comprehensive income (loss)	(5,559)	0	0	0	0	(5,559)	0
Balance at Jun. 30, 2012	1,029,300	243,790	16	2,017,563	(1,256,790)	(3,621)	28,342
Balance at Dec. 31, 2012	1,333,165	243,790	18	2,212,949	(1,143,803)	(6,224)	26,435
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redemption of noncontrolling OP units for common shares	0	0	0	861	0	0	(861)
Repurchase Of Preferred Shares	(155,004)	(149,774)	0	0	(5,230)	0	0
Issuance of common shares upon conversion of convertible notes	47,128	0	0	47,128	0	0	0
Issuance of common shares and deferred compensation amortization, net	307,263	0	3	307,260	0	0	0
Dividends/distributions	(72,850)	0	0	0	(70,872)	0	(1,978)
Net income	5,709	0	0	0	4,112	0	1,597
Other comprehensive income (loss)	10,136	0	0	0	0	10,136	0
Balance at Jun. 30, 2013	$ 1,475,547	$ 94,016	$ 21	$ 2,568,198	$ (1,215,793)	$ 3,912	$ 25,193