Debt - Debt Outstanding and Average Interest Rates (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Debt, gross	$ 902.6
Unamortized issuance costs and discounts	(8.5)	$ (7.9)
Total debt	$ 894.1	839.6
Line of Credit | Revolving credit facilities
Debt Instrument [Line Items]
Average interest rate at end of period	1.107%
Debt, gross	$ 195.0	36.1
Term loans | Term Loans, 1.224% due in 2023
Debt Instrument [Line Items]
Average interest rate at end of period	1.033%
Debt, gross	$ 200.0	200.0
Senior Notes | Senior Notes, 5.000% due 2021
Debt Instrument [Line Items]
Average interest rate at end of period	5.00%
Debt, gross	$ 0.0	103.8
Senior Notes | Senior Notes 3.150% due 2022
Debt Instrument [Line Items]
Average interest rate at end of period	3.15%
Debt, gross	$ 88.3	88.3
Senior Notes | Senior Notes, 4.650% due in 2025
Debt Instrument [Line Items]
Average interest rate at end of period	4.65%
Debt, gross	$ 19.3	19.3
Senior Notes | Senior Notes, 4.500% due in 2029
Debt Instrument [Line Items]
Average interest rate at end of period	4.50%
Debt, gross	$ 400.0	$ 400.0