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, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Continuing Operations:
Income from continuing operations									$ 176,117	$ 121,601	$ 116,365
Gain on dispositions									100,714	59,621	146,290
Net income attributable to noncontrolling interests									(37,898)	(6,870)	(19,623)
Dividends on preferred shares									0	(3,830)	(10,840)
Redemption costs of preferred shares									0	(9,687)	0
Income from continuing operations attributable to common shareholders – basic									238,933	160,835	232,192
Income attributable to operating partnership units									1,996	0	2,171
Income from continuing operations attributable to common shareholders – diluted									240,929	160,835	234,363
Discontinued Operations:
Income from discontinued operations									0	0	44,924
Net loss attributable to noncontrolling interests									0	0	52
Income from discontinued operations attributable to common shareholders – basic and diluted									0	0	44,976
Net Income:
Net Income Attributable to Common Shareholders	$ 44,142	$ 51,901	$ 35,816	$ 107,074	$ 47,275	$ 43,401	$ 25,222	$ 44,937	238,933	160,835	277,168
Net income attributable to common shareholders – diluted									$ 240,929	$ 160,835	$ 279,339
Denominator:
Weighted average shares outstanding – basic (in shares)									126,048	123,037	121,542
Effect of dilutive securities:
Share options and awards (in shares)									1,059	1,292	1,331
Operating partnership units (in shares)									1,462	0	1,497
Weighted average shares outstanding - diluted (in shares)									128,569	124,329	124,370