Per Share Data (Calculation Of Basic And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Number of common share equivalent securities excluded from the diluted earnings per share calculation	1,900	2,000	1,500	2,100
Net income attributable to common shareholders	$ 36,079	$ 35,272	$ 151,678	$ 75,308
Amount allocated to participating securities	(251)	(300)	(1,302)	(653)
Net income attributable to common shareholders – basic	$ 35,828	$ 34,972	$ 150,376	$ 74,655
Earnings per common share – basic	$ 0.40	$ 0.40	$ 1.69	$ 0.85
Weighted average number of common shares outstanding – basic	89,153	87,845	89,071	87,748
Income allocated to common units from continuing operations	$ 274	$ 314	$ 1,615	$ 623
Net income attributable to common shareholders – diluted	$ 36,102	$ 35,286	$ 151,991	$ 75,278
Earnings per common share – diluted	$ 0.40	$ 0.40	$ 1.68	$ 0.85
Common share options and share awards granted	288	314	339	338
Common units	811	813	1,086	813
Weighted average number of common shares outstanding – diluted	90,252	88,972	90,496	88,899