Fair Value Measurements - Schedule of Components of Amounts Included in Purchases, Sales, Issuances and Settlements (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract]
Purchases	$ 91	$ 344
Sales	(458)	(351)
Issuances	78	61
Settlements	(47)	(48)
Total	(336)	6
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases, (Sales), Issuances, (Settlements) [Abstract]
Purchases	0
Sales	0
Issuances	(227)
Settlements	152
Total	(75)
Funds withheld payable under reinsurance treaties
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases, (Sales), Issuances, (Settlements) [Abstract]
Purchases	0	0
Sales	0	0
Issuances	(184)	(116)
Settlements	152	102
Total	(32)	(14)
Market risk benefit liabilities
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases, (Sales), Issuances, (Settlements) [Abstract]
Purchases	0
Sales	0
Issuances	(43)
Settlements	0
Total	(43)
Debt Securities \| Corporate securities
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract]
Purchases	1	104
Sales	(191)	(77)
Issuances	0	0
Settlements	0	0
Total	(190)	27
Debt Securities \| Other asset-backed securities
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract]
Purchases	57	158
Sales	(116)	(147)
Issuances	0	0
Settlements	0	0
Total	(59)	11
Debt Securities \| Public utilities
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract]
Purchases		0
Sales		(44)
Issuances		0
Settlements		0
Total		(44)
Mortgage loans
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract]
Purchases	20	81
Sales	(150)	(83)
Issuances	0	0
Settlements	0	0
Total	(130)	(2)
Limited partnerships
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract]
Purchases	13	1
Sales	(1)	0
Issuances	0	0
Settlements	0	0
Total	12	1
Policy loans
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract]
Purchases	0	0
Sales	0	0
Issuances	78	61
Settlements	(47)	(48)
Total	$ 31	$ 13

Amount of issuances 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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