Treasury Stock and Share-Based Awards - Summary of Treasury Stock Activity (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2025 USD ($) shares
Treasury Stock, Number of Shares and Restriction Disclosures [Abstract]
Number of Treasury Shares | shares	6,380,000
Repurchases of common stock, Share | shares	7,930,000	[1]
Restricted stock withholdings | shares	600,000	[2]
Restricted stock forfeitures | shares	30,000.00	[3]
Number of Treasury Shares | shares	14,940,000
Beginning Balance, Cost | $	$ 103.2
Repurchases of common stock | $	201.6	[1]
Restricted stock withholdings | $	17.1	[2]
Restricted stock forfeitures | $	0.0	[3]
Ending Balance, Cost | $	$ 321.9

[1] Holdings repurchased outstanding common shares under a share repurchase program.

[2] Holdings withheld shares as a result of the election by certain employees to satisfy their tax liabilities upon vesting of restricted stock and performance stock units with shares. Holdings determined the number of shares to be withheld based upon market values of Holdings’ common stock on the vesting dates, which ranged from $24.38 to $33.06 per share.

[3] Holdings repurchased forfeited restricted shares at a cost of $0.001 per share in accordance with its Long-Term Incentive Plan.