Investments - Investments in NGP (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Schedule of Equity Method Investments [Line Items]
Total	$ 3,179.3	$ 3,024.1
Global Private Equity
Schedule of Equity Method Investments [Line Items]
Total	1,828.6	1,798.3
Investment in NGP Management | Global Private Equity
Schedule of Equity Method Investments [Line Items]
Total	370.9	370.5
Investments in NGP general partners - accrued performance allocations | Global Private Equity
Schedule of Equity Method Investments [Line Items]
Total	480.6	484.4
Principal investments in NGP funds | Global Private Equity
Schedule of Equity Method Investments [Line Items]
Total	58.3	61.3
Total investments in NGP | Global Private Equity
Schedule of Equity Method Investments [Line Items]
Total	$ 909.8	$ 916.2