Investments - Schedule of Components of Investment Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Net Investment Income [Line Items]
Investment income (loss)	$ 113.9	$ 694.0	$ (502.8)	$ 853.8
Performance allocations
Net Investment Income [Line Items]
Investment income (loss)	44.7	638.8	(636.4)	861.7
Realized
Net Investment Income [Line Items]
Investment income (loss)	307.0	116.7	357.4	449.6
Unrealized
Net Investment Income [Line Items]
Investment income (loss)	(262.3)	522.1	(993.8)	412.1
Principal investment income (loss) from equity method investments (excluding performance allocations)
Net Investment Income [Line Items]
Investment income (loss)	70.7	55.4	147.0	(7.3)
Realized
Net Investment Income [Line Items]
Investment income (loss)	28.1	178.3	50.8	148.9
Unrealized
Net Investment Income [Line Items]
Investment income (loss)	42.6	(122.9)	96.2	(156.2)
Principal investment income (loss) from investments in CLOs and other investments
Net Investment Income [Line Items]
Investment income (loss)	(1.5)	(0.2)	(13.4)	(0.6)
Realized
Net Investment Income [Line Items]
Investment income (loss)	0.2	1.6	3.8	(0.4)
Unrealized
Net Investment Income [Line Items]
Investment income (loss)	$ (1.7)	$ (1.8)	$ (17.2)	$ (0.2)