Investments - Schedule of Investments in NGP (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Schedule of Equity Method Investments [Line Items]
Total	$ 2,982.3	$ 2,879.5
Global Private Equity
Schedule of Equity Method Investments [Line Items]
Total	1,434.7	1,384.4
Total investments in NGP \| Global Private Equity
Schedule of Equity Method Investments [Line Items]
Total	652.4	616.0
Investment in NGP Management \| Global Private Equity
Schedule of Equity Method Investments [Line Items]
Total	238.7	247.4
Investments in NGP general partners - accrued performance allocations \| Global Private Equity
Schedule of Equity Method Investments [Line Items]
Total	368.0	326.2
Principal investments in NGP funds \| Global Private Equity
Schedule of Equity Method Investments [Line Items]
Total	$ 45.7	$ 42.4

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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