Earnings Per Share (Computation Of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 43.2	$ 43.7	$ 48.8	$ 49.5	$ 86.9	$ 98.3
Average basic shares outstanding (in shares)	56.8		56.7		56.8	56.7
Effect of dilutive share-based awards (in shares)	0.6		0.0		0.6	0.0
Average diluted shares outstanding (in shares)	57.4		56.7		57.4	56.7
Earnings per basic share (in dollars per share)	$ 0.76		$ 0.86		$ 1.53	$ 1.73
Earnings per diluted share (in dollars per share)	$ 0.75		$ 0.86		$ 1.51	$ 1.73