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, 2013	Mar. 31, 2012
Earnings Per Share [Abstract]
Number of common share equivalent securities excluded from the diluted earnings per share calculation	3,000,000	1,400,000
Income from continuing operations attributable to common shareholders	$ 30,985	$ 53,958
Amount allocated to participating securities	(638)	(890)
Income from continuing operations attributable to common shareholders, net of amount allocated to participating securities	30,347	53,068
Income from discontinued operations, including gain on sale, attributable to common shareholders	32,491	34,800
Net income attributable to common shareholders, as adjusted	62,838	87,868
Income from continuing operations attributable to common shareholders, as adjusted - per share	$ 0.35	$ 0.66
Income from discontinued operations, including gain on sale, attributable to common shareholders	$ 0.37	$ 0.44
Net income attributable to common shareholders, as adjusted - per share	$ 0.72	$ 1.10
Weighted average number of common shares outstanding - basic	86,703,000	79,885,000
Income allocated to common units from continuing operations	0	639
Income from continuing operations attributable to common shareholders, as adjusted	30,347	53,707
Net income attributable to common shareholders, as adjusted	$ 62,838	$ 88,507
Income from continuing operations attributable to common shareholders, as adjusted - per share	$ 0.35	$ 0.65
Income from discontinued operations, including gain on sale, attributable to common shareholders - per share	$ 0.37	$ 0.42
Net income attributable to common shareholders, as adjusted - per share	$ 0.72	$ 1.07
Common share options and share awards granted	573,000	679,000
Common units	0	2,291,000
Weighted average number of common shares outstanding - diluted	87,276,000	82,855,000