Per Share Data (Calculation Of Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Earnings Per Share [Abstract]
Number of common share equivalent securities excluded from the diluted earnings per share calculation	1,400,000	4,100,000
Income from continuing operations attributable to common shareholders	$ 56,534	$ 6,503
Amount allocated to participating securities	(890)	(104)
Income from continuing operations attributable to common shareholders, net of amount allocated to participating securities	55,644	6,399
Income from discontinued operations, including gain on sale, attributable to common shareholders	32,224	783
Net income attributable to common shareholders, as adjusted	87,868	7,182
Income from continuing operations attributable to common shareholders, as adjusted - per share	$ 0.70	$ 0.09
Income from discontinued operations, including gain on sale, attributable to common shareholders	$ 0.40	$ 0.01
Net income attributable to common shareholders, as adjusted - per share	$ 1.10	$ 0.10
Weighted average number of common shares outstanding - basic	79,885,000	71,906,000
Income allocated to common units from continuing operations	700	10
Income from continuing operations attributable to common shareholders, as adjusted	56,344	6,409
Net income attributable to common shareholders, as adjusted	$ 88,568	$ 7,192
Income from continuing operations attributable to common shareholders, as adjusted - per share	$ 0.68	$ 0.09
Income from discontinued operations, including gain on sale, attributable to common shareholders - per share	$ 0.39	$ 0.01
Net income attributable to common shareholders, as adjusted - per share	$ 1.07	$ 0.10
Common share options and share awards granted	679,000	638,000
Common units	2,291,000	239,000
Weighted average number of common shares outstanding - diluted	82,855,000	72,783,000