Fair Value (Quantitative information about significant unobservable inputs in the fair value measurement of level 3 assets) (Details) $ in Millions	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Estimated fair value	$ 43,116	$ 43,116
Fixed maturity securities \| Discounted cash flow
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Estimated fair value	$ 1,521	$ 1,495
Credit spread \| Discounted cash flow \| Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Debt securities, available-for-sale, measurement Input	0.01	0.01
Credit spread \| Discounted cash flow \| Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Debt securities, available-for-sale, measurement Input	0.07	0.07
Credit spread \| Discounted cash flow \| Weighted Average
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Debt securities, available-for-sale, measurement Input	0.02	0.02

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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- Definition

Value of input used to measure investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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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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