Net Earnings Per Share - Calculations of Net Earnings Per Share - Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net earnings (loss) available to common shareholders	$ 91.6	$ 62.0
Weighted-average common shares outstanding (in millions)
Weighted-average common shares outstanding - basic	53.6	55.1
Weighted-average common shares outstanding - diluted	54.4	55.7
Net earnings (loss) per share - basic	$ 1.71	$ 1.12
Net earnings (loss) per share - diluted	$ 1.68	$ 1.11
Effect of dilutive securities - stock options
Weighted-average common shares outstanding (in millions)
Effect of dilutive securities	0.1	0.1
Effect of other share-based awards
Weighted-average common shares outstanding (in millions)
Effect of dilutive securities	0.7	0.5