Investments - Schedule of Investments as a Percentage of Investments of Consolidated Funds (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Schedule of Investments [Line Items]
Investments of Consolidated Funds	$ 6,894.4	$ 6,661.0
Percentage of investments in Consolidated Funds	100.00%	100.00%
Assets of the CLOs - Equity
Schedule of Investments [Line Items]
Assets of CLOs	$ 2.1	$ 9.4
Percentage of assets of the CLOs	0.03%	0.14%
United States
Schedule of Investments [Line Items]
Investments of Consolidated Funds	$ 3,743.3	$ 2,955.6
Percentage of investments in Consolidated Funds	54.29%	44.37%
United States | Equity securities
Schedule of Investments [Line Items]
Equity securities	$ 427.3	$ 0.0
Percentage of equity securities	6.20%	0.00%
United States | Partnership and LLC interests
Schedule of Investments [Line Items]
Fund investments	$ 515.9	$ 120.5
Percentage of fund investments	7.48%	1.81%
United States | Loans
Schedule of Investments [Line Items]
Loans	$ 23.4	$ 157.0
Loans percentage	0.34%	2.36%
United States | Assets of the CLOs - Bonds
Schedule of Investments [Line Items]
Assets of CLOs	$ 57.5	$ 40.2
Percentage of assets of the CLOs	0.83%	0.60%
United States | Assets of the CLOs - Equity
Schedule of Investments [Line Items]
Assets of CLOs	$ 1.3	$ 8.5
Percentage of assets of the CLOs	0.02%	0.13%
United States | Assets of the CLOs - Loans
Schedule of Investments [Line Items]
Assets of CLOs	$ 2,717.9	$ 2,629.4
Percentage of assets of the CLOs	39.42%	39.47%
United States | Total assets of the CLOs
Schedule of Investments [Line Items]
Assets of CLOs	$ 2,776.7	$ 2,678.1
Percentage of assets of the CLOs	40.27%	40.20%
Europe
Schedule of Investments [Line Items]
Investments of Consolidated Funds	$ 3,062.8	$ 3,625.8
Percentage of investments in Consolidated Funds	44.43%	54.43%
Europe | Assets of the CLOs - Bonds
Schedule of Investments [Line Items]
Assets of CLOs	$ 533.5	$ 557.6
Percentage of assets of the CLOs	7.74%	8.37%
Europe | Assets of the CLOs - Loans
Schedule of Investments [Line Items]
Assets of CLOs	$ 2,527.2	$ 3,058.8
Percentage of assets of the CLOs	36.66%	45.92%
Europe | Total assets of the CLOs
Schedule of Investments [Line Items]
Assets of CLOs	$ 3,062.8	$ 3,625.8
Percentage of assets of the CLOs	44.43%	54.43%
Global
Schedule of Investments [Line Items]
Investments of Consolidated Funds	$ 88.3	$ 79.6
Percentage of investments in Consolidated Funds	1.28%	1.20%
Global | Assets of the CLOs - Bonds
Schedule of Investments [Line Items]
Assets of CLOs	$ 3.9	$ 1.7
Percentage of assets of the CLOs	0.06%	0.03%
Global | Assets of the CLOs - Loans
Schedule of Investments [Line Items]
Assets of CLOs	$ 84.4	$ 77.9
Percentage of assets of the CLOs	1.22%	1.17%
Global | Total assets of the CLOs
Schedule of Investments [Line Items]
Assets of CLOs	$ 88.3	$ 79.6
Percentage of assets of the CLOs	1.28%	1.20%
Infrastructure | United States | Equity securities
Schedule of Investments [Line Items]
Equity securities	$ 413.4	$ 0.0
Percentage of equity securities	6.00%	0.00%
Aerospace & Defense | United States
Schedule of Investments [Line Items]
Loans percentage	0.16%	1.20%
Aerospace & Defense | United States | Loans
Schedule of Investments [Line Items]
Loans	$ 10.9	$ 79.8
Collateralized Debt Obligation | United States
Schedule of Investments [Line Items]
Loans percentage	0.17%	0.00%
Collateralized Debt Obligation | United States | Loans
Schedule of Investments [Line Items]
Loans	$ 11.6	$ 0.0
Environmental Industries | United States | Loans
Schedule of Investments [Line Items]
Loans	$ 0.9	$ 0.9
Loans percentage	0.01%	0.01%
Investment Company | United States
Schedule of Investments [Line Items]
Loans percentage	0.00%	0.77%
Investment Company | United States | Loans
Schedule of Investments [Line Items]
Loans	$ 0.0	$ 51.3
Other | United States
Schedule of Investments [Line Items]
Loans percentage	0.00%	0.38%
Other | United States | Equity securities
Schedule of Investments [Line Items]
Equity securities	$ 13.9	$ 0.0
Percentage of equity securities	0.20%	0.00%
Other | United States | Loans
Schedule of Investments [Line Items]
Loans	$ 0.0	$ 25.0