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		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Business Combinations [Abstract]
Beginning balance	$ 254.2	$ 250.9	$ 251.7	$ 291.0
Additions to estimated acquisition earn-out payables	20.6	6.1	40.3	16.9
Payments for estimated acquisition earn-out payables	(47.4)	(19.6)	(63.6)	(66.5)
Subtotal	227.4	237.4	228.4	241.4
Net change in earnings from estimated acquisition earn-out payables:
Change in fair value on estimated acquisition earn-out payables		(4.7)	(4.3)	(9.5)
Interest expense accretion	1.8	1.7	3.8	3.1
Net change in earnings from estimated acquisition earn-out payables	1.8	(3.0)	(0.5)	(6.4)
Foreign currency translation adjustments during the year	2.3	(1.5)	3.6	(2.1)
Ending balance	$ 231.5	$ 232.9	$ 231.5	$ 232.9