Investments - Schedule of Components of Investment Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Net Investment Income [Line Items]
Investment income (loss)	$ (616.7)	$ 159.8
Performance allocations
Net Investment Income [Line Items]
Investment income (loss)	(681.1)	222.9
Realized
Net Investment Income [Line Items]
Investment income (loss)	50.4	332.9
Unrealized
Net Investment Income [Line Items]
Investment income (loss)	(731.5)	(110.0)
Principal investment income (loss) from equity method investments (excluding performance allocations)
Net Investment Income [Line Items]
Investment income (loss)	76.3	(62.7)
Realized
Net Investment Income [Line Items]
Investment income (loss)	22.7	(29.4)
Unrealized
Net Investment Income [Line Items]
Investment income (loss)	53.6	(33.3)
Principal investment income (loss) from investments in CLOs and other investments
Net Investment Income [Line Items]
Investment income (loss)	(11.9)	(0.4)
Realized
Net Investment Income [Line Items]
Investment income (loss)	3.6	(2.0)
Unrealized
Net Investment Income [Line Items]
Investment income (loss)	$ (15.5)	$ 1.6