Fair Value - Significant Unobservable Inputs (Details) $ in Millions	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Quantitative Information About the Significant Unobservable Inputs [Abstract]
Estimated Fair Value	$ 38,243	$ 37,697
Level 3 \| Fixed maturity securities
Quantitative Information About the Significant Unobservable Inputs [Abstract]
Estimated Fair Value	$ 1,359	$ 1,177
Debt Securities, Available-for-sale, Valuation Technique [Extensible List]	Discounted cash flow	Discounted cash flow
Debt Securities, Available-for-sale, Measurement Input [Extensible List]	Credit spread	Credit spread
Level 3 \| Fixed maturity securities \| Credit spread \| Discounted cash flow \| Minimum
Quantitative Information About the Significant Unobservable Inputs [Abstract]
Measurement input	0.01	0.01
Level 3 \| Fixed maturity securities \| Credit spread \| Discounted cash flow \| Maximum
Quantitative Information About the Significant Unobservable Inputs [Abstract]
Measurement input	0.07	0.08
Level 3 \| Fixed maturity securities \| Credit spread \| Discounted cash flow \| Weighted Average
Quantitative Information About the Significant Unobservable Inputs [Abstract]
Measurement input	(0.02)	(0.02)

Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479130/326-30-45-1

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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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Indicates measurement input for 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)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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- Definition

Indicates valuation technique for measuring investment in debt security 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)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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