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Stock-Based Compensation Plans - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized (in shares)	21,400,000
Number of common shares available for grant (in shares)	2,200,000
Award vesting percentage	50.00%
Income tax benefit	$ 16.3	$ 12.8	$ 13.9
Fair value of restricted stock awards	54.2	49.7	39.9
Unrecognized stock compensation expense	$ 42.7
Unrecognized stock compensation expense, recognition period (in years)	1 year 9 months 18 days
Total intrinsic value of options exercised	$ 0.1	0.3	2.2
Exercise of stock options	0.1	0.3	1.8
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 56.8	$ 55.1	$ 54.5
Incentive Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual life (in years)	ten
Number of options outstanding (in shares)	0
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	1 year
Minimum \| Performance-Based
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	0.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	3 years
Maximum \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common shares available for grant (in shares)	300,000
Maximum \| Performance-Based
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	150.00%