Insurance (Guarantees Related to Annuity Contracts) (Details) - Variable Annuity Guarantees - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2020	Dec. 31, 2019
Guaranteed Death Benefits
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value (3)	$ 84,118	$ 100,034
Separate account value	79,412	95,430
Net amount at risk	$ 12,837	$ 6,617
Average attained age of contract holders	70 years	69 years
Guaranteed Annuitization Benefits
Net Amount at Risk by Product and Guarantee [Line Items]
Total account value (3)	$ 48,027	$ 57,069
Separate account value	46,952	56,027
Net amount at risk	$ 9,710	$ 4,495
Average attained age of contract holders	70 years	69 years

Value of the general accounts corresponding to the specified product, guarantee type and subset of the guarantee.

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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

Net amount at risk, representing the guaranteed benefit in excess of the current account balance corresponding to the specified product, guarantee type and subset of the guarantee.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 80
-Section 50
-Paragraph 1
-Subparagraph (d)(3),(5)
-URI http://asc.fasb.org/extlink&oid=117420044&loc=d3e19393-158473

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section 55
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=117418410&loc=d3e7104-158389

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- Definition

Value of the separate accounts corresponding to the specified product, guarantee type and subset of the guarantee.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 80
-Section 50
-Paragraph 1
-Subparagraph ((d)(1))
-URI http://asc.fasb.org/extlink&oid=117420044&loc=d3e19393-158473

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section 55
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=117418410&loc=d3e7104-158389

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- Definition

Weighted average attained age of policyholders or contract holders in the specified guarantee type and subset of guarantee class, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 80
-Section 50
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=117420044&loc=d3e19393-158473

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-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=117418410&loc=d3e7104-158389

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- Details

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