Earnings Per Share (Components Of Earnings Per Common Share - Basic And Diluted) (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Continuing Operations:
Income from continuing operations									$ 121,601	$ 116,365	$ 132,977
Gain on sale of property									59,621	146,290	762
Net income attributable to noncontrolling interests									(6,870)	(19,623)	(5,545)
Dividends on preferred shares									(3,830)	(10,840)	(18,173)
Redemption costs of preferred shares									(9,687)	0	(17,944)
Income from continuing operations attributable to common shareholders – basic									160,835	232,192	92,077
Income attributable to operating partnership units									0	2,171	0
Income from continuing operations attributable to common shareholders – diluted									160,835	234,363	92,077
Discontinued Operations:
Income from discontinued operations									0	44,924	131,417
Net loss (income) attributable to noncontrolling interests									0	52	(39,349)
Income from discontinued operations attributable to common shareholders – basic and diluted									0	44,976	92,068
Net Income:
Net Income Attributable to Common Shareholders	$ 47,275	$ 43,401	$ 25,222	$ 44,937	$ 86,270	$ 97,619	$ 32,686	$ 60,593	160,835	277,168	184,145
Net income attributable to common shareholders – diluted									$ 160,835	$ 279,339	$ 184,145
Denominator:
Weighted average shares outstanding - basic (in shares)									123,037	121,542	121,269
Effect of dilutive securities:
Share options and awards (in shares)									1,292	1,331	1,191
Operating partnership units (in shares)									0	1,497	0
Weighted average shares outstanding - diluted (in shares)									124,329	124,370	122,460