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, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 41.6	$ 37.8	$ 43.2	$ 43.7	$ 79.4	$ 86.9
Average basic shares outstanding (in shares)	57.1		56.8		57.1	56.8
Effect of dilutive share-based awards (in shares)	0.7		0.6		0.6	0.6
Average diluted shares outstanding (in shares)	57.8		57.4		57.7	57.4
Earnings per basic share (in dollars per share)	$ 0.73		$ 0.76		$ 1.39	$ 1.53
Earnings per diluted share (in dollars per share)	$ 0.72		$ 0.75		$ 1.38	$ 1.51