Per Share Data (Calculation Of Basic And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share [Abstract]
Number of common share equivalent securities excluded from the diluted earnings per share calculation	1,700	1,500
Income from continuing operations attributable to common shareholders	$ 36,654	$ 110,730
Amount allocated to participating securities	(232)	(1,052)
Income from continuing operations attributable to common shareholders, net of amount allocated to participating securities	36,422	109,678
Income from discontinued operations attributable to common shareholders	5,076	4,869
Net income attributable to common shareholders, as adjusted – basic	$ 41,498	$ 114,547
Earnings per common share from continuing operations	$ 0.41	$ 1.23
Earnings per common share from discontinued operations	0.05	0.06
Total earnings per common share – basic	$ 0.46	$ 1.29
Weighted average number of common shares outstanding – basic	89,344	88,987
Income allocated to common units from continuing operations	$ 328	$ 766
Income from continuing operations attributable to common shareholders, as adjusted	36,750	110,444
Net income attributable to common shareholders – diluted	$ 41,826	$ 115,313
Earnings per common share from continuing operations	$ 0.41	$ 1.22
Earnings per common share from discontinued operations	0.05	0.05
Total earnings per common share – diluted	$ 0.46	$ 1.27
Common share options and share awards granted	355	391
Common units	810	1,086
Weighted average number of common shares outstanding – diluted	90,509	90,464