Revenue Contract Balances (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Accounts receivable, net of allowance of $37.0 and $46.4, respectively	$ 5,649.7	$ 5,768.8
Accounts receivable, billable to clients	2,088.4	2,229.2
Contract with Customer, Asset, after Allowance for Credit Loss	50.1	68.6
Contract liabilities	509.0	684.7
Revenue, remaining performance obligation, amount	598.5
Net revenue	$ 9,187.6	$ 9,400.6