Business Combinations - Additions, Payments, and Net Changes, as well as Interest Expense Accretion on Estimated Acquisition Earn-Out Payables (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Business Combinations [Abstract]
Beginning balance	$ 251.6	$ 291.0	$ 258.9
Additions to estimated acquisition earn-out payables from new acquisitions	67.2	73.3	75.8
Assumed estimated acquisition earn-out payables	21.1	34.8
Payments for estimated acquisition earn-out payables	(118.8)	(106.3)	(83.6)
Subtotal	221.1	292.8	251.1
Net change in earnings from estimated acquisition earn-out payables:
Change in fair value on estimated acquisition earn-out payables	14.1	(45.9)	34.2
Interest expense accretion	7.7	7.0	6.2
Net change in earnings from estimated acquisition earn-out payables	21.8	(38.9)	40.4
Foreign currency translation adjustments during the year	6.3	(2.3)	(0.5)
Ending balance	$ 249.2	$ 251.6	$ 291.0