Per Share Data (Calculation Of Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]
Number of common share equivalent securities excluded from the diluted earnings per share calculation	2,900,000	3,300,000	2,100,000	2,400,000
Income from continuing operations attributable to common shareholders	$ 34,662	$ 26,814	$ 111,791	$ 98,391
Amount allocated to participating securities	(623)	(288)	(1,958)	(1,387)
Income from continuing operations attributable to common shareholders, net of amount allocated to participating securities	34,039	26,526	109,833	97,004
Income from discontinued operations, including gain on sale, attributable to common shareholders	36,058	3,889	94,577	42,833
Net income attributable to common shareholders, as adjusted	70,097	30,415	204,410	139,837
Income from continuing operations attributable to common shareholders, as adjusted - per share	$ 0.39	$ 0.31	$ 1.26	$ 1.17
Income from discontinued operations, including gain on sale, attributable to common shareholders - per share	$ 0.41	$ 0.05	$ 1.09	$ 0.52
Net income attributable to common shareholders, as adjusted - per share	$ 0.80	$ 0.36	$ 2.35	$ 1.69
Weighted average number of common shares outstanding - basic	87,449,000	85,631,000	87,117,000	82,923,000
Income allocated to common units from continuing operations	0	0	947	985
Income from continuing operations attributable to common shareholders, as adjusted	34,039	26,526	110,780	97,989
Income from discontinued operations allocated to common units	0	0	1,778	852
Net income attributable to common shareholders, as adjusted	$ 70,097	$ 30,415	$ 207,135	$ 141,674
Income from continuing operations attributable to common shareholders, as adjusted - per share	$ 0.39	$ 0.31	$ 1.25	$ 1.16
Income from discontinued operations, including gain on sale, attributable to common shareholders - per share	$ 0.41	$ 0.04	$ 1.09	$ 0.51
Net income attributable to common shareholders, as adjusted - per share	$ 0.80	$ 0.35	$ 2.34	$ 1.67
Common share options and share awards granted	453,000	662,000	497,000	655,000
Common units	0	0	815,000	1,116,000
Weighted average number of common shares outstanding - diluted	87,902,000	86,293,000	88,429,000	84,694,000