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, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Number of common share equivalent securities excluded from the diluted earnings per share calculation	1,900	1,900
Income from continuing operations attributable to common shareholders	$ 43,284	$ 38,613
Amount allocated to participating securities	(99)	(84)
Net income attributable to common shareholders – basic	$ 43,185	$ 38,529
Total earnings per common share – basic	$ 0.43	$ 0.40
Net income attributable to common shareholders – diluted	$ 43,185	$ 38,529
Total earnings per common share – diluted	$ 0.43	$ 0.40
Weighted average number of common shares outstanding – basic	99,298	96,892
Common share options and share awards granted	82	149
Weighted average number of common shares outstanding – diluted	99,380	97,041