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Other Investments (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Dec. 31, 2020	Jun. 30, 2021
NAV of investments at fair value
Unfunded Commitments	$ 122.2	$ 128.5
Life of funds (generally up to)		15 years
Investment without a readily determinable fair value	13.8	$ 13.8
Investment without a readily determinable fair value, upward price adjustment	5.3
Private equity funds
NAV of investments at fair value
Unfunded Commitments	122.2	128.5
Investments in other strategies
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	243.4	298.3
Fair Value Measured at NAV | Controlling Interest
NAV of investments at fair value
Fair Value	164.4	202.3
Fair Value Measured at NAV | Private equity funds
NAV of investments at fair value
Fair Value	235.4	281.2
Fair Value Measured at NAV | Investments in other strategies
NAV of investments at fair value
Fair Value	$ 8.0	$ 17.1

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+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
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The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments).

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