Fair Value Measurements - Level 3 Rollforwards (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Purchases, Sales, Issuances and Settlements	$ (336)	$ 6
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Purchases, Sales, Issuances and Settlements	(75)
Funds withheld payable under reinsurance treaties
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value	(1,971)	(1,353)
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	24	(193)
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	0	0
Purchases, Sales, Issuances and Settlements	(32)	(14)
Transfers in and/or (out of ) Level 3	0	0
Fair Value	(1,979)	(1,560)
Market risk benefit liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value	(3,754)	(3,774)
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	(507)	(678)
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	333	327
Purchases, Sales, Issuances and Settlements	(43)	0
Transfers in and/or (out of ) Level 3	0	0
Fair Value	(3,971)	(4,125)
Debt Securities \| Public utilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value		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		0
Debt Securities \| Corporate securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value	346	274
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	2	0
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	2	4
Purchases, Sales, Issuances and Settlements	(190)	27
Transfers in and/or (out of ) Level 3	(15)	(5)
Fair Value	145	300
Debt Securities \| Other asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value	426	661
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	(19)	0
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	(1)	(2)
Purchases, Sales, Issuances and Settlements	(59)	11
Transfers in and/or (out of ) Level 3	(69)	121
Fair Value	278	791
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value	7	7
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	2	0
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	0	0
Purchases, Sales, Issuances and Settlements	0	0
Transfers in and/or (out of ) Level 3	0	0
Fair Value	9	7
Mortgage loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value	324	449
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	2	4
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	0	0
Purchases, Sales, Issuances and Settlements	(130)	(2)
Transfers in and/or (out of ) Level 3	0	0
Fair Value	196	451
Limited partnerships
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value	250	195
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	4	7
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	0	0
Purchases, Sales, Issuances and Settlements	12	1
Transfers in and/or (out of ) Level 3	10	0
Fair Value	276	203
Policy loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value	3,537	3,489
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	(12)	(10)
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	0	0
Purchases, Sales, Issuances and Settlements	31	13
Transfers in and/or (out of ) Level 3	0	0
Fair Value	3,556	3,492
Reinsurance recoverable on market risk benefits
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value	118	121
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	3	5
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	0	0
Purchases, Sales, Issuances and Settlements	0	0
Transfers in and/or (out of ) Level 3	0	0
Fair Value	121	126
Market risk benefit assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value	7,867	8,899
Total Realized/Unrealized Gains (Losses) Included in Net Income (Loss)	(1,166)	(1,573)
Total Realized/Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss)	0	0
Purchases, Sales, Issuances and Settlements	0	0
Transfers in and/or (out of ) Level 3	0	0
Fair Value	$ 6,701	$ 7,326

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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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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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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