Net Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Numerator:
Net earnings	$ 61.9	$ 149.2
Distributed and allocated undistributed net earnings to unvested restricted stockholders	0.0	0.0
Net earnings available to common stockholders	$ 61.9	$ 149.2
Denominator:
Weighted average number of common shares outstanding - basic (in shares)	144.1	147.6
Basic net earnings per common share:
Basic net earnings per common share (in dollars per share)	$ 0.43	$ 1.01
Numerator:
Net earnings available to common stockholders	$ 61.9	$ 149.2
Denominator:
Weighted average number of common shares outstanding - basic (in shares)	144.1	147.6
Effect of unvested restricted stock units (in shares)	0.7	1.9
Weighted average number of common shares outstanding - diluted under treasury stock (in shares)	144.8	149.5
Diluted net earnings per common share (in dollars per share)	$ 0.43	$ 1.00