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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Number of common share equivalent securities excluded from the diluted earnings per share calculation	2,000	2,000	1,900	2,000
Income from continuing operations attributable to common shareholders	$ 16,477	$ 42,399	$ 59,761	$ 81,012
Amount allocated to participating securities	(35)	(117)	(134)	(186)
Net income attributable to common shareholders – basic	$ 16,442	$ 42,282	$ 59,627	$ 80,826
Total earnings per common share – basic	$ 0.17	$ 0.43	$ 0.60	$ 0.83
Net income attributable to common shareholders – diluted	$ 16,442	$ 42,282	$ 59,627	$ 80,826
Total earnings per common share – diluted	$ 0.17	$ 0.43	$ 0.60	$ 0.82
Weighted average number of common shares outstanding – basic	99,399	98,903	99,348	97,903
Common share options and share awards granted	9	94	46	121
Weighted average number of common shares outstanding – diluted	99,408	98,997	99,394	98,024