Derivative Financial Instruments - Net Realized Gains (Losses) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivatives, Fair Value [Line Items]
Net investment income	$ 586	$ 712	$ 1,284	$ 1,370
Other net realized capital gains (losses)	49	28	(164)	42
Amount of Gain or (Loss) Recognized in Other Comprehensive Income	(85)	(168)	(233)	(348)
Interest rate contracts \| Net Investment Income \| Designated as Hedging Instrument \| Cash Flow Hedging
Derivatives, Fair Value [Line Items]
Amount of Gain or (Loss) Reclassified from Accumulated Other Comprehensive Income	0	0	0	0
Interest rate contracts \| Other Comprehensive Income (Loss) \| Designated as Hedging Instrument \| Cash Flow Hedging
Derivatives, Fair Value [Line Items]
Amount of Gain or (Loss) Reclassified from Accumulated Other Comprehensive Income	0	1	2	2
Foreign exchange contracts \| Net Investment Income \| Designated as Hedging Instrument \| Cash Flow Hedging
Derivatives, Fair Value [Line Items]
Amount of Gain or (Loss) Recognized in Other Comprehensive Income	3	3	6	6
Amount of Gain or (Loss) Reclassified from Accumulated Other Comprehensive Income	3	3	6	6
Foreign exchange contracts \| Other Comprehensive Income (Loss) \| Designated as Hedging Instrument \| Cash Flow Hedging
Derivatives, Fair Value [Line Items]
Amount of Gain or (Loss) Reclassified from Accumulated Other Comprehensive Income	(19)	20	73	10
Foreign exchange contracts \| Other net realized capital gains/(losses) \| Designated as Hedging Instrument \| Cash Flow Hedging
Derivatives, Fair Value [Line Items]
Amount of Gain or (Loss) Recognized in Other Comprehensive Income	$ 0	$ 0	$ 0	$ 0

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5618551-113959

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The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4D
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624177-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Paragraph 4C
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959

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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.

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No definition available.

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Amount of gain (loss) included in earnings for investments classified as other.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
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Amount, after investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(2))
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