Derivative Financial Instruments and Off-balance sheet Financial Instruments - CDS notional amounts by credit rating (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Derivative Financial Instruments and Off-balance sheet Financial Instruments
Term of credit default swaps	5 years
Credit Derivatives
Derivative, notional amount	$ 2,075	$ 5,191
Credit default contracts
Credit Derivatives
Derivative, notional amount	255	754
Fair value	6	13
Credit default contracts \| Single name \| Corporate
Credit Derivatives
Derivative, notional amount	5	4
Fair value	0	0
Credit default contracts \| Index \| Corporate
Credit Derivatives
Derivative, notional amount	250	750
Fair value	6	13
AAA \| Credit default contracts
Credit Derivatives
Derivative, notional amount	2	6
AAA \| Credit default contracts \| Single name \| Corporate
Credit Derivatives
Derivative, notional amount	0	0
AAA \| Credit default contracts \| Index \| Corporate
Credit Derivatives
Derivative, notional amount	2	6
AA \| Credit default contracts
Credit Derivatives
Derivative, notional amount	4	12
AA \| Credit default contracts \| Single name \| Corporate
Credit Derivatives
Derivative, notional amount	0	0
AA \| Credit default contracts \| Index \| Corporate
Credit Derivatives
Derivative, notional amount	4	12
A \| Credit default contracts
Credit Derivatives
Derivative, notional amount	46	156
A \| Credit default contracts \| Single name \| Corporate
Credit Derivatives
Derivative, notional amount	0	0
A \| Credit default contracts \| Index \| Corporate
Credit Derivatives
Derivative, notional amount	46	156
BBB \| Credit default contracts
Credit Derivatives
Derivative, notional amount	190	492
BBB \| Credit default contracts \| Single name \| Corporate
Credit Derivatives
Derivative, notional amount	0	0
BBB \| Credit default contracts \| Index \| Corporate
Credit Derivatives
Derivative, notional amount	190	492
BB and lower \| Credit default contracts
Credit Derivatives
Derivative, notional amount	13	88
BB and lower \| Credit default contracts \| Single name \| Corporate
Credit Derivatives
Derivative, notional amount	5	4
BB and lower \| Credit default contracts \| Index \| Corporate
Credit Derivatives
Derivative, notional amount	$ 8	$ 84

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- Definition

Term of the credit risk derivative contract, 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 815
-SubTopic 10
-Section 50
-Paragraph 4K
-Subparagraph (a)(1)
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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.

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- Definition

Fair value of credit risk derivative asset after deduction of credit risk derivative liability.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4K
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=125515794&loc=SL5708775-113959

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- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=125515794&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=125515794&loc=SL5579245-113959

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