Per Share Data (Calculation Of Basic And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Number of common share equivalent securities excluded from the diluted earnings per share calculation	1,900	2,100	1,900	2,200
Income from continuing operations attributable to common shareholders	$ 43,597	$ 38,866	$ 124,609	$ 116,932
Amount allocated to participating securities	(89)	(284)	(284)	(831)
Net income attributable to common shareholders – basic	$ 43,508	$ 38,582	$ 124,325	$ 116,101
Total earnings per common share – basic	$ 0.44	$ 0.41	$ 1.27	$ 1.22
Net income attributable to common shareholders – diluted	$ 43,508	$ 38,582	$ 124,325	$ 116,101
Total earnings per common share – diluted	$ 0.44	$ 0.40	$ 1.26	$ 1.22
Weighted average number of common shares outstanding – basic	98,959	95,257	98,259	95,190
Common share options and share awards granted	107	160	116	143
Weighted average number of common shares outstanding – diluted	99,066	95,417	98,375	95,333