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Investments - Investments Measured at NAV as a Practical Expedient (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
NAV of investments at fair value
Fair Value	$ 488.6	$ 430.5
Unfunded Commitments	$ 205.5	187.2
Life of funds (generally up to)	15 years
Investments with limited liquidity
NAV of investments at fair value
Unfunded Commitments	$ 205.5	187.2
Investments with periodic liquidity
NAV of investments at fair value
Unfunded Commitments	0.0	0.0
Fair Value Measured at NAV
NAV of investments at fair value
Fair Value	488.6	430.5
Fair Value Measured at NAV | Controlling Interest
NAV of investments at fair value
Fair Value	370.1	324.9
Fair Value Measured at NAV | Investments with limited liquidity
NAV of investments at fair value
Fair Value	486.9	424.4
Fair Value Measured at NAV | Investments with periodic liquidity
NAV of investments at fair value
Fair Value	$ 1.7	$ 6.1

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