Earnings per Share - Reconciliation of Numerator and Denominator of Basic and Diluted Earnings per Share Calculation and Anti-dilutive Share-based Awards (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Earnings Per Share Basic And Diluted [Line Items]
Basic	$ 0.80	$ 1.05
Diluted	$ 0.77	$ 1.02
Net earnings	$ 26.4	$ 35.2
Weighted average number of common shares outstanding	32.9	33.6
Dilutive awards	1.5	0.9
Diluted weighted average number of common shares outstanding	34.4	34.5
Restricted stock units
Earnings Per Share Basic And Diluted [Line Items]
Total weighted average number of anti-dilutive share-based awards	0.0	0.2