Investments - Schedule of Fair Value of Foreign Currency Exchange Forward Contracts (Details) - Foreign Currency Exchange Forward Contracts - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Schedule of Investments [Line Items]
Foreign currency exchange, fair value	$ (1.7)	$ 1.3
Operational currency
Schedule of Investments [Line Items]
Foreign currency exchange, fair value	0.0	1.5
Open contracts in a gain position
Schedule of Investments [Line Items]
Foreign currency exchange, notional amount	0.0	75.4
Foreign currency exchange, fair value	0.0	1.8
Open contracts in a loss position
Schedule of Investments [Line Items]
Foreign currency exchange, notional amount	0.0	43.3
Foreign currency exchange, fair value	0.0	(0.3)
Asset manager investment exposure
Schedule of Investments [Line Items]
Foreign currency exchange, fair value	(1.7)	(0.2)
Open contracts in a loss position
Schedule of Investments [Line Items]
Foreign currency exchange, notional amount	78.3	45.8
Foreign currency exchange, fair value	$ (1.7)	$ (0.2)