Derivatives (Credit Derivatives) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2026	Dec. 31, 2025
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 196	$ 152
Maximum Amount of Future Payments under Credit Default Swaps	$ 14,754	$ 8,873
Weighted Average Years to Maturity	4 years 6 months	3 years 2 months 12 days
Aaa/Aa/A
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 37	$ 45
Maximum Amount of Future Payments under Credit Default Swaps	$ 3,836	$ 3,836
Weighted Average Years to Maturity	1 year 2 months 12 days	1 year 4 months 24 days
Aaa/Aa/A \| Single name credit default swaps (3)
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 1	$ 1
Maximum Amount of Future Payments under Credit Default Swaps	$ 59	$ 59
Weighted Average Years to Maturity	2 years 3 months 18 days	2 years 6 months
Aaa/Aa/A \| Credit default swaps referencing indices
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 36	$ 44
Maximum Amount of Future Payments under Credit Default Swaps	$ 3,777	$ 3,777
Weighted Average Years to Maturity	1 year 1 month 6 days	1 year 4 months 24 days
Baa
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 145	$ 96
Maximum Amount of Future Payments under Credit Default Swaps	$ 10,574	$ 4,853
Weighted Average Years to Maturity	5 years 8 months 12 days	4 years 7 months 6 days
Baa \| Single name credit default swaps (3)
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 1	$ 1
Maximum Amount of Future Payments under Credit Default Swaps	$ 46	$ 46
Weighted Average Years to Maturity	3 years 7 months 6 days	3 years 9 months 18 days
Baa \| Credit default swaps referencing indices
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 144	$ 95
Maximum Amount of Future Payments under Credit Default Swaps	$ 10,528	$ 4,807
Weighted Average Years to Maturity	5 years 8 months 12 days	4 years 7 months 6 days
B
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 14	$ 10
Maximum Amount of Future Payments under Credit Default Swaps	$ 305	$ 145
Weighted Average Years to Maturity	3 years 10 months 24 days	2 years 8 months 12 days
B \| Single name credit default swaps (3)
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 0	$ 0
Maximum Amount of Future Payments under Credit Default Swaps	$ 16	$ 16
Weighted Average Years to Maturity	3 months 18 days	7 months 6 days
B \| Credit default swaps referencing indices
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 14	$ 10
Maximum Amount of Future Payments under Credit Default Swaps	$ 289	$ 129
Weighted Average Years to Maturity	4 years 1 month 6 days	3 years
Caa
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ (1)	$ 0
Maximum Amount of Future Payments under Credit Default Swaps	$ 15	$ 15
Weighted Average Years to Maturity	8 months 12 days	1 year
Caa \| Credit default swaps referencing indices
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ (1)	$ 0
Maximum Amount of Future Payments under Credit Default Swaps	$ 15	$ 15
Weighted Average Years to Maturity	8 months 12 days	1 year
Ba
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 1	$ 1
Maximum Amount of Future Payments under Credit Default Swaps	$ 24	$ 24
Weighted Average Years to Maturity	8 months 12 days	1 year
Ba \| Credit default swaps referencing indices
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 1	$ 1
Maximum Amount of Future Payments under Credit Default Swaps	$ 24	$ 24
Weighted Average Years to Maturity	8 months 12 days	1 year

Maximum potential amount of future undiscounted payments that could be required under the credit derivative, before reduction for potential recoveries under recourse or collateralization provisions.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4K
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4K

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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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 10
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-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4K

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4K

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
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-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4K

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4K
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4K

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- Definition

Average remaining period until maturity of the derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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