Fair Value Measurements - Schedule of Portion of Gains (Losses) Included in Net Income or Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Funds withheld payable under reinsurance treaties
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Included in Net Income	$ 269	$ (269)	$ 94	$ (673)
Included in OCI	0	0	0	0
Market risk benefit liabilities
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Included in Net Income	650	421	863	566
Included in OCI	(167)	(585)	103	(525)
Debt securities \| Corporate securities
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Included in Net Income	(7)	0	(2)	10
Included in OCI	(5)	1	(9)	4
Debt securities \| Other asset-backed securities
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Included in Net Income	(29)	(13)	(46)	(64)
Included in OCI	14	5	(11)	32
Equity securities
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Included in Net Income	2	0	5	0
Included in OCI	0	0	0	0
Mortgage loans
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Included in Net Income	(8)	(2)	(2)	5
Included in OCI	0	0	0	0
Limited partnerships
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Included in Net Income	8	6	28	15
Included in OCI	0	0	0	0
Policy loans
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Included in Net Income	62	73	135	144
Included in OCI	0	0	0	0
Reinsurance recoverable on market risk benefits
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Included in Net Income	(22)	5	(31)	(5)
Included in OCI	0	0	0	0
Market risk benefit assets
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Line Items]
Included in Net Income	443	(200)	622	(378)
Included in OCI	$ 0	$ 0	$ 0	$ 0

Amount of unrealized gain (loss) recognized in other comprehensive income (OCI) from asset (liability) measured at fair value on recurring basis using unobservable input (level 3) and still held.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
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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 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
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Amount of unrealized gain (loss) recognized in income for derivative asset (liability) after deduction of derivative liability (asset), measured at fair value using unobservable input (level 3) and still held.

+ References

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

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
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-Name Accounting Standards Codification
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-3

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