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, 2026	Mar. 31, 2025
Earnings Per Share [Abstract]
Net income	$ 117.2	$ 129.6
Weighted average number of shares outstanding, basic (in shares)	34.8	35.5
Add: Potential effect of dilutive securities attributable to stock-based payments	0.2	0.2
Weighted-average shares outstanding – diluted	35.0	35.7
Earnings per share - Basic (in dollars per share)	$ 3.37	$ 3.65
Earnings per share - Diluted (in dollars per share)	$ 3.35	$ 3.63