Condensed Consolidated Statements of Equity (Unaudited) - USD ($) $ in Thousands		Total	Preferred Shares Of Beneficial Interest [Member]	Common Shares Of Beneficial Interest [Member]	Additional Paid-In Capital [Member]	Net Income Less Than Accumulated Dividends [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interests [Member]
Beginning Balance at Dec. 31, 2013		$ 1,687,978	$ 2	$ 3,683	$ 1,679,229	$ (300,537)	$ (4,202)	$ 309,803
Increase (Decrease) in Equity [Roll Forward]
Net Income		101,765				98,699		3,066
Shares issued under benefit plans		7,322		8	7,314
Dividends paid - common shares	[1]	(79,427)				(79,427)
Dividends paid - preferred shares	[2]	(4,876)				(4,876)
Distributions to noncontrolling interests		(3,305)						(3,305)
Contributions from noncontrolling interests		980						980
Acquisition of noncontrolling interests		0			11,015			(11,015)
Disposition of noncontrolling interests		(144,263)						(144,263)
Other comprehensive income		1,290					1,290
Other, net		(451)			225	(544)		(132)
Ending Balance at Jun. 30, 2014		1,567,013	2	3,691	1,697,783	(286,685)	(2,912)	155,134
Beginning Balance at Dec. 31, 2013		1,687,978	2	3,683	1,679,229	(300,537)	(4,202)	309,803
Ending Balance at Dec. 31, 2014		1,638,943	2	3,700	1,706,880	(212,960)	(12,436)	153,757
Increase (Decrease) in Equity [Roll Forward]
Net Income		87,008				83,676		3,332
Redemption of preferred shares		(150,000)	(2)		(140,311)	(9,687)
Issuance of common shares, net		40,345		34	40,311
Shares issued under benefit plans		7,229		10	7,219
Shares issued in exchange for noncontrolling interests		0			111			(111)
Dividends paid - common shares	[1]	(85,233)				(85,233)
Dividends paid - preferred shares	[2]	(3,873)				(3,873)
Distributions to noncontrolling interests		(3,938)						(3,938)
Other comprehensive income		6,893					6,893
Other, net		(471)			280	43		(794)
Ending Balance at Jun. 30, 2015		$ 1,536,903	$ 0	$ 3,744	$ 1,614,490	$ (228,034)	$ (5,543)	$ 152,246

[1] Common dividend per share was $.69 and $.65 for the six months ended June 30, 2015 and 2014, respectively.

[2] Series F preferred dividend per share was $64.55 and $81.25 for the six months ended June 30, 2015 and 2014, respectively.