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Fair Value Measurements - Summary of Gains and Losses (Realized and Unrealized) Relating to Level 3 Assets and Liabilities Included in Earnings (Details) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2021 | Mar. 31, 2020
Net Investment Income [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Total gains or losses included in earnings for the period | $ 0 | $ 0
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held | 0 | 0
Gain (Loss) on Derivative Instruments [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Total gains or losses included in earnings for the period | (17) | 12
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held | (17) | 12
Income Loss On Variable Interest Entities [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Total gains or losses included in earnings for the period | (129) | 118
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held | (129) | 118
Other Income or (Loss) [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Total gains or losses included in earnings for the period | 0 | 0
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held | $ 0 | $ 0

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- Definition The amount of gains or losses included in earnings attributable to unrealized gains or losses on financial instruments measured on a recurring basis using unobservable inputs that are still held at the reporting date. + References No definition available. + Details
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- Definition Amount of gain (loss) recognized in income from asset and liability measured at fair value on recurring basis using unobservable input (level 3). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
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- Definition Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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