Earnings Per Share (Components Of Earnings Per Common Share - Basic And Diluted) (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Continuing Operations:
Income from continuing operations	$ 31,956	$ 32,703	$ 88,279	$ 87,633
Gain on sale of property	13,232	69,496	43,917	71,407
Net income attributable to noncontrolling interests	(1,787)	(1,870)	(5,119)	(4,988)
Dividends on preferred shares	0	(2,710)	(3,830)	(8,130)
Redemption costs of preferred shares	0	0	(9,687)	0
Income from continuing operations attributable to common shareholders – basic	43,401	97,619	113,560	145,922
Income attributable to operating partnership units	472	455	0	1,368
Income from continuing operations attributable to common shareholders – diluted	43,873	98,074	113,560	147,290
Discontinued Operations:
Income from discontinued operations	0	0	0	44,924
Net loss attributable to noncontrolling interests	0	0	0	52
Income from discontinued operations attributable to common shareholders – basic and diluted	0	0	0	44,976
Net Income:
Net income attributable to common shareholders – basic	43,401	97,619	113,560	190,898
Net income attributable to common shareholders – diluted	$ 43,873	$ 98,074	$ 113,560	$ 192,266
Denominator:
Weighted average shares outstanding – basic (in shares)	123,349	121,560	122,929	121,487
Effect of dilutive securities:
Share options and awards (in shares)	1,222	1,385	1,303	1,316
Operating partnership units (in shares)	1,462	1,495	0	1,498
Weighted average shares outstanding – diluted (in shares)	126,033	124,440	124,232	124,301