Earnings Per Share - Computation of Basic and Diluted Income Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Numerator:
Net Income (Loss)	$ 203.8	$ 146.9
Less: Distributed and undistributed earnings allocated to participating securities	(1.4)	(1.0)
Net income attributable to common shareholders	$ 202.4	$ 145.9
Denominator:
Weighted average basic common shares outstanding	89.2	89.0
Effect of dilutive securities	0.4	0.4
Weighted average diluted common shares outstanding	89.6	89.4
Basic income per common share	$ 2.27	$ 1.64
Diluted income per common share	$ 2.26	$ 1.63