Business Combinations - Additions, Payments, and Net Changes, as well as Interest Expense Accretion on Estimated Acquisition Earn-Out Payables (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Business Combinations [Abstract]
Beginning balance	$ 231.5	$ 232.9	$ 251.7	$ 291.0
Additions to estimated acquisition earn-out payables	11.1	25.2	51.3	42.1
Assumed acquisition earn-out payables		34.8		34.8
Payments for estimated acquisition earn-out payables	(11.0)	(10.6)	(74.5)	(77.1)
Subtotal	231.6	282.3	228.5	290.8
Net change in earnings from estimated acquisition earn-out payables:
Change in fair value on estimated acquisition earn-out payables	27.8	(28.5)	23.5	(38.1)
Interest expense accretion	2.1	1.9	5.9	5.0
Net change in earnings from estimated acquisition earn-out payables	29.9	(26.6)	29.4	(33.1)
Foreign currency translation adjustments during the year	(3.3)	(5.8)	0.3	(7.8)
Ending balance	$ 258.2	$ 249.9	$ 258.2	$ 249.9