Earnings per Share - Reconciliation of Numerator and Denominator of Net Earnings per Basic and Diluted Share Calculations and Anti-dilutive Share Based Awards (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Earnings Per Share Basic And Diluted [Line Items]
Basic	$ 1.3	$ 1.5	$ 2.38	$ 2.63
Diluted	$ 1.28	$ 1.47	$ 2.33	$ 2.56
Net earnings	$ 36.1	$ 44.1	$ 67.1	$ 77.4
Weighted average number of common shares outstanding	27.7	29.4	28.2	29.4
Dilutive awards	0.5	0.6	0.6	0.8
Diluted weighted average number of common shares outstanding	28.2	30.0	28.8	30.2
Restricted stock units
Earnings Per Share Basic And Diluted [Line Items]
Total weighted average number of anti-dilutive share-based awards	0.1	0.0	0.2	0.1

Earnings per Share - Reconciliation of Numerator and Denominator of Net Earnings per Basic and Diluted Share Calculations and Anti-dilutive Share Based Awards (Detail) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions

3 Months Ended

6 Months Ended

Jun. 30, 2025

Jun. 30, 2024

Jun. 30, 2025

Jun. 30, 2024

Earnings Per Share Basic And Diluted [Line Items]

Basic

$ 1.3

$ 1.5

$ 2.38

$ 2.63

Diluted

$ 1.28

$ 1.47

$ 2.33

$ 2.56

Net earnings

$ 36.1

$ 44.1

$ 67.1

$ 77.4

Weighted average number of common shares outstanding

27.7

29.4

28.2

29.4

Dilutive awards

0.5

0.6

0.8

Diluted weighted average number of common shares outstanding

28.2

30.0

28.8

30.2

Restricted stock units

Earnings Per Share Basic And Diluted [Line Items]

Total weighted average number of anti-dilutive share-based awards

0.1

0.0

0.2

0.1

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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+ Details