Investments - Schedule of Components of Investment Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Net Investment Income [Line Items]
Investment income (loss)	$ (507.3)	$ (519.0)	$ (1,010.1)	$ 334.8
Performance allocations
Net Investment Income [Line Items]
Investment income (loss)	(626.6)	(606.7)	(1,263.0)	255.0
Realized
Net Investment Income [Line Items]
Investment income (loss)	211.6	49.4	569.0	499.0
Unrealized
Net Investment Income [Line Items]
Investment income (loss)	(838.2)	(656.1)	(1,832.0)	(244.0)
Principal investment income (loss) from equity method investments (excluding performance allocations)
Net Investment Income [Line Items]
Investment income (loss)	115.5	68.0	262.5	60.7
Realized
Net Investment Income [Line Items]
Investment income (loss)	144.6	59.6	195.4	208.5
Unrealized
Net Investment Income [Line Items]
Investment income (loss)	(29.1)	8.4	67.1	(147.8)
Principal investment income (loss) from investments in CLOs and other investments
Net Investment Income [Line Items]
Investment income (loss)	3.8	19.7	(9.6)	19.1
Realized
Net Investment Income [Line Items]
Investment income (loss)	3.1	1.1	6.9	0.7
Unrealized
Net Investment Income [Line Items]
Investment income (loss)	$ 0.7	$ 18.6	$ (16.5)	$ 18.4