Investments - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Parenthetical) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Cash and Cash Equivalents, at Carrying Value	$ 432.2	$ 440.1	$ 564.0
Cash and cash equivalents	131.7	156.5
Restricted Cash	1.8	2.2
Funds Held for Clients	$ 2,079.1	$ 515.8