Fair Value Measurements - Level 3 Rollforwards (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Purchases, Sales, Issuances and Settlements	$ (79)	$ (25)	$ (15)	$ 91
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Purchases, Sales, Issuances and Settlements	110		4
Funds withheld payable under reinsurance treaties
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	(2,155)	(1,784)	(1,971)	(1,353)
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	269	(269)	94	(673)
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	0	0	0	0
Purchases, Sales, Issuances and Settlements	145	66	136	39
Transfers in and/or (out of ) Level 3	0	0	0	0
Fair Value, end of period	(1,741)	(1,987)	(1,741)	(1,987)
Market risk benefit liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	(3,368)	(3,569)	(3,754)	(3,774)
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	650	421	863	566
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	(167)	(585)	103	(525)
Purchases, Sales, Issuances and Settlements	(35)	0	(132)	0
Transfers in and/or (out of ) Level 3	0	0	0	0
Fair Value, end of period	(2,920)	(3,733)	(2,920)	(3,733)
Debt securities \| Public utilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period				44
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)				0
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)				0
Purchases, Sales, Issuances and Settlements				(44)
Transfers in and/or (out of ) Level 3				0
Fair Value, end of period		0		0
Debt securities \| Corporate securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	134	374	346	274
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	(7)	(1)	(2)	9
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	(5)	2	(4)	5
Purchases, Sales, Issuances and Settlements	26	(1)	(159)	96
Transfers in and/or (out of ) Level 3	(26)	23	(59)	13
Fair Value, end of period	122	397	122	397
Debt securities \| Commercial mortgage-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	0		0
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	0		0
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	0		0
Purchases, Sales, Issuances and Settlements	15		15
Transfers in and/or (out of ) Level 3	0		0
Fair Value, end of period	15		15
Debt securities \| Other asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	284	852	426	661
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	(29)	(12)	(46)	(64)
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	14	5	7	33
Purchases, Sales, Issuances and Settlements	68	(34)	15	111
Transfers in and/or (out of ) Level 3	38	(335)	(27)	(265)
Fair Value, end of period	375	476	375	476
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	10	7	7	7
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	2	0	5	0
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	0	0	0	0
Purchases, Sales, Issuances and Settlements	0	0	0	0
Transfers in and/or (out of ) Level 3	0	0	0	0
Fair Value, end of period	12	7	12	7
Mortgage loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	595	393	324	449
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	8	(2)	(2)	5
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	0	0	0	0
Purchases, Sales, Issuances and Settlements	(46)	(42)	235	(105)
Transfers in and/or (out of ) Level 3	0	0	0	0
Fair Value, end of period	557	349	557	349
Limited partnerships
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	314	205	250	195
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	8	6	28	15
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	0	0	0	0
Purchases, Sales, Issuances and Settlements	2	73	16	74
Transfers in and/or (out of ) Level 3	0	0	30	0
Fair Value, end of period	324	284	324	284
Policy loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	3,617	3,540	3,537	3,489
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	62	73	135	144
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	0	0	0	0
Purchases, Sales, Issuances and Settlements	(144)	(21)	(137)	(41)
Transfers in and/or (out of ) Level 3	0	0	0	0
Fair Value, end of period	3,535	3,592	3,535	3,592
Reinsurance recoverable on market risk benefits
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	109	111	118	121
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	(22)	5	(31)	(5)
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	0	0	0	0
Purchases, Sales, Issuances and Settlements	0	0	0	0
Transfers in and/or (out of ) Level 3	0	0	0	0
Fair Value, end of period	87	116	87	116
Market risk benefit assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	8,046	8,721	7,867	8,899
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	443	(200)	622	(378)
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	0	0	0	0
Purchases, Sales, Issuances and Settlements	0	0	0	0
Transfers in and/or (out of ) Level 3	0	0	0	0
Fair Value, end of period	$ 8,489	$ 8,521	$ 8,489	$ 8,521

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

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

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No definition available.

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- Definition

Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

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

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Amount of purchases, (sales), issuances and (settlements) of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfer of financial instrument classified as an asset into (out of) level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of gain (loss) recognized in income from liability measured at fair value on recurring basis using unobservable input (level 3).

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

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Amount of transfers of financial instrument classified as a liability into (out of) level 3 of the fair value hierarchy.

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