Investments - Investment in NGP (Additional Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Basis difference			$ 1.4
Amortization period of basis difference	10 years
Percentage of carried interest income allocated to partnership for future carry funds	47.50%
CLO Senior and Subordinated Notes and Derivative Instruments
Schedule of Equity Method Investments [Line Items]
Investment in preferred securities	$ 532.6	$ 526.1
Minimum
Schedule of Equity Method Investments [Line Items]
Performance allocations, carry funds, percentage (percent)	40.00%
Minimum | Total investments in NGP
Schedule of Equity Method Investments [Line Items]
Management fee - percentage of commitments	1.00%
Management fee - percentage of invested capital	0.50%
Maximum
Schedule of Equity Method Investments [Line Items]
Performance allocations, carry funds, percentage (percent)	42.75%
Maximum | Total investments in NGP
Schedule of Equity Method Investments [Line Items]
Management fee - percentage of commitments	2.00%
Management fee - percentage of invested capital	2.00%
Investment in NGP Management | Management Fee Related Revenues
Schedule of Equity Method Investments [Line Items]
Percentage of income allocated under partnership investment	55.00%
Total investments in NGP
Schedule of Equity Method Investments [Line Items]
Performance fees, income (loss)	$ 65.5	560.7	3.8
Investment income, income (loss)	8.0	44.5	$ 20.1
TCG BDC
Schedule of Equity Method Investments [Line Items]
Investment in preferred securities	$ 81.7	$ 76.9