Fair Value, Quantitative Information about Significant Unobservable Inputs Utilized by Company in Fair Value Measurements of Level 3 Assets (Details) $ in Millions	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Quantitative Information About the Significant Unobservable Inputs [Abstract]
Estimated fair value	$ 40,124	$ 42,240
Level 3 [Member] \| Fixed Maturity Securities [Member]
Quantitative Information About the Significant Unobservable Inputs [Abstract]
Estimated fair value	$ 583	$ 525
Debt Securities, Available-for-sale, Valuation Technique [Extensible List]	us-gaap:ValuationTechniqueDiscountedCashFlowMember	us-gaap:ValuationTechniqueDiscountedCashFlowMember
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Level 3 [Member] \| Fixed Maturity Securities [Member] \| Credit Spread [Member] \| Discounted Cash Flow [Member] \| Minimum [Member]
Quantitative Information About the Significant Unobservable Inputs [Abstract]
Measurement input	0.01	0.01
Level 3 [Member] \| Fixed Maturity Securities [Member] \| Credit Spread [Member] \| Discounted Cash Flow [Member] \| Maximum [Member]
Quantitative Information About the Significant Unobservable Inputs [Abstract]
Measurement input	0.10	0.06
Level 3 [Member] \| Fixed Maturity Securities [Member] \| Credit Spread [Member] \| Discounted Cash Flow [Member] \| Weighted Average [Member]
Quantitative Information About the Significant Unobservable Inputs [Abstract]
Measurement input	0.04	0.02

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Indicates measurement input for investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Indicates valuation technique for measuring investment in debt security at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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