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Investments - Investments Measured at NAV as a Practical Expedient (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Dec. 31, 2024
NAV of investments at fair value
Fair Value	$ 475.9	$ 488.6
Unfunded Commitments	$ 228.9	205.5
Life of funds (generally up to)	15 years
Investments With Limited Liquidity
NAV of investments at fair value
Unfunded Commitments	$ 228.9	205.5
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	475.9	488.6
Fair Value Measured at NAV | Controlling Interest
NAV of investments at fair value
Fair Value	358.6	370.1
Fair Value Measured at NAV | Investments With Limited Liquidity
NAV of investments at fair value
Fair Value	450.6	486.9
Fair Value Measured at NAV | Investments With Periodic Liquidity
NAV of investments at fair value
Fair Value	$ 25.3	$ 1.7

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