Condensed Consolidated Statements Of Equity (USD $)		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]
Balance at Dec. 31, 2012		$ 1,740,155,000	$ 7,000	$ 3,663,000	$ 1,934,183,000	$ (335,980,000)	$ (24,743,000)	$ 163,025,000
Increase (Decrease) in Equity [Roll Forward]
Net Income		44,817,000				43,350,000		1,467,000
Redemption of preferred shares		(75,000,000)	(3,000)		(72,755,000)	(2,242,000)
Shares issued under benefit plans		6,408,000		8,000	6,400,000
Dividends declared - common shares	[1]	(37,127,000)				(37,127,000)
Dividends declared - preferred shares	[2]	(6,995,000)				(6,995,000)
Distributions to noncontrolling interests		(3,858,000)						(3,858,000)
Other comprehensive (loss) income		(1,086,000)					(1,086,000)
Other, net		426,000			387,000	(445,000)		484,000
Balance at Mar. 31, 2013		1,667,740,000	4,000	3,671,000	1,868,215,000	(339,439,000)	(25,829,000)	161,118,000
Balance at Dec. 31, 2013		1,687,978,000	2,000	3,683,000	1,679,229,000	(300,537,000)	(4,202,000)	309,803,000
Increase (Decrease) in Equity [Roll Forward]
Net Income		64,781,000				63,303,000		1,478,000
Shares issued under benefit plans		5,630,000		7,000	5,623,000
Dividends declared - common shares	[1]	(39,703,000)				(39,703,000)
Dividends declared - preferred shares	[2]	(2,438,000)				(2,438,000)
Distributions to noncontrolling interests		(2,351,000)						(2,351,000)
Acquisition of noncontrolling interests		0			10,932,000			(10,932,000)
Disposition of noncontrolling interests		(144,326,000)						(144,326,000)
Other comprehensive (loss) income		581,000					581,000
Other, net		(221,000)			51,000	(272,000)
Balance at Mar. 31, 2014		$ 1,569,931,000	$ 2,000	$ 3,690,000	$ 1,695,835,000	$ (279,647,000)	$ (3,621,000)	$ 153,672,000

[1] Common dividend per share was $.325 and $.305 for the three months ended March 31, 2014 and 2013, respectively.

[2] Series D preferred dividend per share was $13.08 for the three months ended March 31, 2013. Series F preferred dividend per share was $40.63 for both the three months ended March 31, 2014 and 2013, respectively.