Investments - Schedule of Investments Measured at NAV as a Practical Expedient (Details) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2026	Dec. 31, 2025
NAV of investments at fair value
Fair Value	$ 600.8	$ 576.4
Life of funds (generally up to)	15 years
Fair Value Measured at NAV
NAV of investments at fair value
Fair Value	$ 600.8	576.4
Fair Value Measured at NAV \| Controlling Interest
NAV of investments at fair value
Fair Value	486.4	456.6
Fair Value Measured at NAV \| Investments with limited liquidity
NAV of investments at fair value
Fair Value	558.5	535.7
Fair Value Measured at NAV \| Investments with periodic liquidity
NAV of investments at fair value
Fair Value	$ 42.3	$ 40.7

Fair value of investment other than investment in equity security, investment in debt security and equity method investment. Includes, but is not limited to, investment in certain entities that calculate net asset value per share. Example includes, but is not limited to, investment in hedge fund, venture capital fund, private equity fund, and real estate partnership or fund.

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- 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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