Available-For-Sale Fixed Maturity Securities - Allowance for Credit Loss for Available-for-Sale Fixed Maturity Securities (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ (2)	$ (37)	$ (27)	$ (24)
Credit losses recognized on securities for which credit losses were not previously recorded	(3)	(3)	(15)	(36)
Reductions for securities sold during the period		2	16	3
Allowance on securities that had an allowance recorded in a previous period	2	16	23	35
Ending balance	(3)	(22)	(3)	(22)
U.S. State and Political Subdivisions
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Roll Forward]
Beginning balance	0	0	0	0
Credit losses recognized on securities for which credit losses were not previously recorded	(3)	0	(3)	0
Reductions for securities sold during the period		0	0	0
Allowance on securities that had an allowance recorded in a previous period	0	0	0	0
Ending balance	(3)	0	(3)	0
Corporate debt securities
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Roll Forward]
Beginning balance	(1)	(34)	(26)	(19)
Credit losses recognized on securities for which credit losses were not previously recorded	0	(3)	(10)	(36)
Reductions for securities sold during the period		2	16	3
Allowance on securities that had an allowance recorded in a previous period	1	15	20	32
Ending balance	0	(20)	0	(20)
Residential mortgage-backed securities
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Roll Forward]
Beginning balance	0	(1)	(1)	(1)
Credit losses recognized on securities for which credit losses were not previously recorded	0	0	0	0
Reductions for securities sold during the period		0	0	0
Allowance on securities that had an allowance recorded in a previous period	0	0	1	0
Ending balance	0	(1)	0	(1)
Commercial mortgage-backed securities
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Roll Forward]
Beginning balance			0
Ending balance	0		0
Collateralized debt securities
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Roll Forward]
Beginning balance	(1)	(2)	0	(4)
Credit losses recognized on securities for which credit losses were not previously recorded	0	0	(2)	0
Reductions for securities sold during the period		0	0	0
Allowance on securities that had an allowance recorded in a previous period	1	1	2	3
Ending balance	$ 0	$ (1)	$ 0	$ (1)

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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- Definition

Amount excluding accrued interest, of allowance for credit loss on 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 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479130/326-30-45-1

+ Details

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- Definition

Amount, excluding accrued interest, of credit loss expense on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) with no credit loss previously recorded.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479106/326-30-50-9

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476148/220-40-50-22

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- Definition

Amount, excluding accrued interest, of credit loss expense (reversal of expense) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) with previously recorded allowance and not intended to be sold and not more likely than not will be required to sell before recovery of amortized cost basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479106/326-30-50-9

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476148/220-40-50-22

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479106/326-30-50-9

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