Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022
Fair value assets and liabilities measured on recurring basis
Cash equivalents		$ 1,521.5	$ 1,688.1
Contingent acquisition obligations	[1]	3.1	21.6
Contingent acquisition obligation, total change		$ (18.5)
Discount rate floor contingent acquisition obligations		3.00%
Level 1
Fair value assets and liabilities measured on recurring basis
Cash equivalents		$ 1,521.5	1,688.1
Contingent acquisition obligations	[1]	0.0	0.0
Level 2
Fair value assets and liabilities measured on recurring basis
Cash equivalents		0.0	0.0
Contingent acquisition obligations	[1]	0.0	0.0
Level 3
Fair value assets and liabilities measured on recurring basis
Cash equivalents		0.0	0.0
Contingent acquisition obligations		$ 3.1	$ 21.6

[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 decrease in this balance of $18.5 from December 31, 2022 to December 31, 2023 is primarily due to payments related to our deferred acquisitions from prior-year acquisitions and valuation adjustments, partially offset by the addition of a new contingent acquisition obligation and the exercises of redeemable non-controlling interest. The amounts payable within the next twelve months are classified in accrued liabilities; any amounts payable thereafter are classified in other non-current liabilities.