Earnings Per Share (Computation Of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 37.8	$ 43.7
Average basic shares outstanding (in shares)	57.0	56.7
Effect of dilutive share-based awards (in shares)	0.7	0.0
Average diluted shares outstanding (in shares)	57.7	56.7
Earnings per basic share (in dollars per share)	$ 0.66	$ 0.77
Earnings per diluted share (in dollars per share)	$ 0.66	$ 0.77