Fair Value on a Recurring and Nonrecurring Basis (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2024	Dec. 31, 2023
Fair value assets and liabilities measured on recurring and nonrecurring basis
Contingent acquisition liability, total change		$ 1.9
Long-term Debt, Fair Value		$ 2,792.4	$ 2,975.3
Discount rate floor contingent acquisition obligations		4.00%
Discount rate ceiling contingent acquisition obligations		6.00%
Level 1
Fair value assets and liabilities measured on recurring and nonrecurring basis
Cash equivalents		$ 472.6	1,521.5
Contingent acquisition obligations	[1]	0.0	0.0
Long-term Debt, Fair Value		0.0	0.0
Level 2
Fair value assets and liabilities measured on recurring and nonrecurring basis
Cash equivalents		0.0	0.0
Contingent acquisition obligations	[1]	0.0	0.0
Long-term Debt, Fair Value		2,792.0	2,974.5
Level 3
Fair value assets and liabilities measured on recurring and nonrecurring basis
Cash equivalents		0.0	0.0
Contingent acquisition obligations	[1]	5.0	3.1
Long-term Debt, Fair Value		0.4	0.8
Fair Value, Total [Member]
Fair value assets and liabilities measured on recurring and nonrecurring basis
Cash equivalents		472.6	1,521.5
Contingent acquisition obligations	[1]	5.0	3.1
Long-term Debt, Fair Value		$ 2,792.4	$ 2,975.3

[1] Contingent acquisition obligations includes deferred acquisition payments and unconditional obligations to purchase additional non-controlling equity shares of consolidated subsidiaries. Fair value measurement of the obligations is based upon actual and projected operating performance targets as specified in the related agreements. The increase in this balance of $1.9 from December 31, 2023 to September 30, 2024 is primarily due to the exercises of redeemable non-controlling interest, partially offset by payments related to our deferred acquisitions from prior-year acquisitions. The amounts payable within the next twelve months are classified in accrued liabilities; any amounts payable thereafter are classified in other non-current liabilities.