Capital Stock and Earnings Per Share - Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net earnings	$ 342.0	$ 436.5	$ 385.5
Denominator:
Basic weighted average common shares outstanding (in shares)	168.4	168.4	168.4
Effect of dilutive stock options and RSUs (in shares)	1.0	0.0	0.0
Diluted weighted average common shares outstanding (in shares)	169.4	168.4	168.4
Earnings per share:
Earnings per share, Basic (in dollars per share)	$ 2.03	$ 2.59	$ 2.29
Earnings per share, Diluted (in dollars per share)	$ 2.02	$ 2.59	$ 2.29
Anti-dilutive shares (in shares)	2.7	0.0	0.0