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Fair Value Measurements - Fair Value of Direct and Indirect Investments, Related Unfunded Commitments and Financial Support Provided (Details) - Principal Investments - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 52
Unfunded Commitments	16
Funded Commitments	2	$ 0
Funded Other	0	0
Direct investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	1
Unfunded Commitments	0
Funded Commitments	0	0
Funded Other	0	0
Indirect investments (measured at NAV)
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	51
Unfunded Commitments	16
Funded Commitments	2	0
Funded Other	$ 0	$ 0

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- Definition

Fair Value, Investments, Entities That Calculate Net Asset Value Per Share, Fair Value

+ References

No definition available.

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- Definition

Fair Value Investments, Funded Commitments.

+ References

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Fair Value Investments, Funded Other

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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.

+ References

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- Definition

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).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=SL6742756-110258

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