Condensed Consolidated Statements of Equity (Unaudited) - USD ($) $ in Thousands		Total	Preferred Shares of Beneficial Interest	Common Shares of Beneficial Interest	Additional Paid-In Capital	Net Income Less Than Accumulated Dividends	Accumulated Other Comprehensive Loss	Noncontrolling Interests
Beginning 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, net		7,229		10	7,219
Dividends paid - common shares	[1]	(85,233)				(85,233)
Distributions to noncontrolling interests		(3,938)						(3,938)
Other comprehensive income		6,893					6,893
Shares issued in exchange for noncontrolling interests		0			111			(111)
Dividends paid - preferred shares	[2]	(3,873)				(3,873)
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
Beginning Balance at Dec. 31, 2015		1,545,010	0	3,744	1,616,242	(222,880)	(7,644)	155,548
Increase (Decrease) in Equity [Roll Forward]
Net Income		146,318				142,890		3,428
Issuance of common shares, net		123,789		99	123,690
Shares issued under benefit plans, net		4,886		35	4,851
Change in classification of deferred compensation plan		(37,488)
Change in redemption value of deferred compensation plan		(14,471)				(14,471)
Diversification of share awards within deferred compensation plan		3,819			3,819
Dividends paid - common shares	[1]	(91,675)				(91,675)
Distributions to noncontrolling interests		(3,493)						(3,493)
Other comprehensive income		(6,989)					(6,989)
Ending Balance at Jun. 30, 2016		$ 1,669,706	$ 0	$ 3,878	$ 1,711,114	$ (186,136)	$ (14,633)	$ 155,483

[1] Common dividend per share was $.73 and $.69 for the six months ended June 30, 2016 and 2015, respectively.

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