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, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]
Number of common share equivalent securities excluded from the diluted earnings per share calculation	1,900,000	2,100,000	2,000,000	2,100,000
Income from continuing operations attributable to common shareholders	$ 38,283	$ 34,044	$ 113,591	$ 109,994
Amount allocated to participating securities	(317)	(623)	(970)	(1,958)
Income from continuing operations attributable to common shareholders, net of amount allocated to participating securities	37,966	33,421	112,621	108,036
Discontinued operations, including gain on sale, attributable to common shareholders	0	36,676	0	96,374
Discontinued operations, including gain on sale, allocated to common units	0	53	0	1,910
Net income attributable to common shareholders – basic	37,966	70,097	112,621	204,410
Earnings per common share continuing operations	$ 0.43	$ 0.38	$ 1.28	$ 1.24
Earnings per common share from discontinued operations	$ 0.00	$ 0.42	$ 0.00	$ 1.11
Total earnings per common share – basic	$ 0.43	$ 0.80	$ 1.28	$ 2.35
Weighted average number of common shares outstanding – basic	88,146,000	87,449,000	87,882,000	87,117,000
Income allocated to common units from continuing operations	313	274	937	814
Income from continuing operations attributable to common shareholders, as adjusted	38,279	33,695	113,558	108,850
Net income attributable to common shareholders – diluted	$ 38,279	$ 70,424	$ 113,558	$ 207,134
Earnings per common share from continuing operations	$ 0.43	$ 0.38	$ 1.28	$ 1.23
Earnings per common share from discontinued operations	$ 0.00	$ 0.41	$ 0.00	$ 1.11
Total earnings per common share – diluted	$ 0.43	$ 0.79	$ 1.28	$ 2.34
Common share options and share awards granted	396,000	453,000	358,000	497,000
Common units	811,000	814,000	812,000	815,000
Weighted average number of common shares outstanding – diluted	89,353,000	88,716,000	89,052,000	88,429,000