Investments - Income (Loss) from Principal Investments (Details) - Principal investment income (loss) from equity method investments - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Schedule of Investments [Line Items]
Principal investment income from equity method investments	$ 56.5	$ (13.9)	$ 103.6	$ (5.6)
Global Private Equity
Schedule of Investments [Line Items]
Principal investment income from equity method investments	37.3	62.8	66.1	80.6
Global Credit
Schedule of Investments [Line Items]
Principal investment income from equity method investments	19.6	(75.5)	31.0	(94.4)
Global Investment Solutions
Schedule of Investments [Line Items]
Principal investment income from equity method investments	$ (0.4)	$ (1.2)	$ 6.5	$ 8.2