Fair Value Measurements - Schedule of Components of Amounts Included in Purchases, Sales, Issuances and Settlements (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract]
Purchases	$ 452	$ 273	$ 562	$ 617
Sales	(48)	(131)	(513)	(482)
Issuances	11	11	89	72
Settlements	(35)	(44)	(82)	(92)
Total	380	109	56	115
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases, (Sales), Issuances, (Settlements) [Abstract]
Purchases	0		0
Sales	0		0
Issuances	(241)		(468)
Settlements	210		362
Total	(31)		(106)
Funds withheld payable under reinsurance treaties
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases, (Sales), Issuances, (Settlements) [Abstract]
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	(187)	(262)	(371)	(378)
Settlements	210	249	362	351
Total	23	(13)	(9)	(27)
Market risk benefit liabilities
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases, (Sales), Issuances, (Settlements) [Abstract]
Purchases	0		0
Sales	0		0
Issuances	(54)		(97)
Settlements	0		0
Total	(54)		(97)
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)
Debt Securities \| Corporate securities
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract]
Purchases	10	79	11	183
Sales	(4)	(17)	(195)	(94)
Issuances	0	0	0	0
Settlements	0	0	0	0
Total	6	62	(184)	89
Debt Securities \| Other asset-backed securities
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract]
Purchases	0	176	76	334
Sales	(6)	(35)	(130)	(182)
Issuances	0	0	0	0
Settlements	0	0	0	0
Total	(6)	141	(54)	152
Mortgage loans
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract]
Purchases	440	18	460	99
Sales	(38)	(79)	(188)	(162)
Issuances	0	0	0	0
Settlements	0	0	0	0
Total	402	(61)	272	(63)
Limited partnerships
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract]
Purchases	2		15	1
Sales	0		0	0
Issuances	0		0	0
Settlements	0		0	0
Total	2	0	15	1
Policy loans
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, (Sales), Issuances, (Settlements) [Abstract]
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	11	11	89	72
Settlements	(35)	(44)	(82)	(92)
Total	$ (24)	$ (33)	$ 7	$ (20)

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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