Debt - Debt and Average Interest Rates on Debt Outstanding (Detail) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Unamortized debt issuance costs and discounts	$ (15.9)	$ (18.5)
Total debt	$ 1,628.4	1,988.3
Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Average interest rate as of September 30, 2024	6.046%
Debt, gross	$ 0.0	0.0
Term Loans | 5-year Term Loan Facility
Debt Instrument [Line Items]
Average interest rate as of September 30, 2024	6.446%
Debt, gross	$ 825.0	987.5
Term Loans | Term Loans, 1.033% Due 2024
Debt Instrument [Line Items]
Debt, gross	$ 0.0	200.0
Senior Notes | Senior Notes 4.650% Due 2025
Debt Instrument [Line Items]
Average interest rate as of September 30, 2024	4.65%
Debt, gross	$ 19.3	19.3
Senior Notes | Senior Notes 4.500% Due 2029
Debt Instrument [Line Items]
Average interest rate as of September 30, 2024	4.50%
Debt, gross	$ 400.0	400.0
Senior Notes | Senior Notes 5.900%
Debt Instrument [Line Items]
Average interest rate as of September 30, 2024	5.90%
Debt, gross	$ 400.0	$ 400.0