Borrowings - Outstanding Loans Payable of Consolidated Funds (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2026	Dec. 31, 2025
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Borrowing Outstanding	$ 3,045.4	$ 3,025.1
Borrowings	10,755.3	9,423.1
Level III
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Borrowings	10,755.3	9,423.1
Revolving credit facilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Borrowings	33.9	63.0
Revolving credit facilities \| Consolidated Funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Borrowing Outstanding	261.9	63.0
Fair Value	$ 261.9	$ 63.0
Weighted Average Interest Rate	4.74%	6.68%
Weighted Average Remaining Maturity in Years	5 months 15 days	3 years 5 months 12 days
Loans Payable of Consolidated Funds \| Consolidated Funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Borrowing Outstanding	$ 11,831.6	$ 10,567.4
Fair Value	11,716.0	10,426.0
Senior secured notes \| Consolidated Funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Borrowing Outstanding	11,120.6	9,994.8
Fair Value	$ 11,099.0	$ 9,972.1
Weighted Average Interest Rate	5.05%	5.09%
Weighted Average Remaining Maturity in Years	11 years 10 months 13 days	11 years 2 months 4 days
Borrowings	$ 937.5
Senior secured notes \| Level III
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Borrowings	926.7
Senior secured notes \| Level III \| Consolidated Funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Borrowings	926.7	$ 939.9
Subordinated notes \| Consolidated Funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Borrowing Outstanding	449.1	509.6
Fair Value	$ 355.1	$ 390.9
Weighted Average Remaining Maturity in Years	10 years 5 months 8 days	9 years 7 months 24 days