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Fair Value Measurements - Fair Value of Direct and Indirect Investments, Related Unfunded Commitments and Financial Support Provided (Details) - Principal Investments [Member] - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Fair Value | $ 69 |
Unfunded Commitments | 21 |
Funded Commitments | 0 | $ 1
Funded Other | 1 | 0
Direct Investments [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Fair Value | 1 |
Unfunded Commitments | 0 |
Funded Commitments | 0 | 0
Funded Other | 1 | 0
Indirect Investments [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Fair Value | 68 |
Unfunded Commitments | 21 |
Funded Commitments | 0 | 1
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. + Details
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- Definition Fair Value Investments, Funded Commitments. + References No definition available. + Details
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- Definition Fair Value Investments, Funded Other + References No definition available. + Details
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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 No definition available. + Details
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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 + Details
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