Borrowings - Outstanding Loans Payable of Consolidated Funds (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2024	Dec. 31, 2023
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of liabilities	$ 7,623.9	$ 6,298.6
Revolving credit facilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Borrowing Outstanding	177.7	177.9
Fair Value	$ 177.7	$ 177.9
Weighted Average Interest Rate	6.67%	6.46%
Weighted Average Remaining Maturity in Years	4 years 5 months 8 days	5 years 18 days
Loans Payable of Consolidated Funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Borrowing Outstanding	$ 7,794.8	$ 6,523.3
Fair Value	7,801.1	6,486.5
Senior secured notes
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Borrowing Outstanding	7,346.9	6,171.9
Fair Value	$ 7,378.8	$ 6,097.9
Weighted Average Interest Rate	6.57%	6.32%
Weighted Average Remaining Maturity in Years	9 years 7 months 20 days	8 years 11 months 26 days
Fair value of liabilities		$ 7.8
Subordinated notes
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Borrowing Outstanding	$ 270.2	173.5
Fair Value	$ 244.6	$ 210.7
Weighted Average Remaining Maturity in Years	9 years 3 months 3 days	9 years 1 month 28 days
Fair value of liabilities		$ 2.2