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Investments - Investments - Available-for-Sale Securities (Details) - USD ($) $ in Millions	Sep. 30, 2025	Jun. 30, 2025	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, at fair value, amortized cost	$ 46,051		$ 44,538
Allowance for credit losses, fixed maturity, AFS	(14)	$ (14)	(16)	$ (16)	$ (19)	$ (21)
Gross Unrealized Gains, fixed maturities, available-for-sale	618		272
Gross Unrealized Losses, fixed maturities, available-for-sale	(1,452)		(2,227)
Fixed maturities, available-for-sale, at fair value (amortized cost of $54,478 and $53,805)	45,203		42,567
ABS
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, at fair value, amortized cost	4,470		3,948
Allowance for credit losses, fixed maturity, AFS	0		0
Gross Unrealized Gains, fixed maturities, available-for-sale	53		28
Gross Unrealized Losses, fixed maturities, available-for-sale	(17)		(39)
Fixed maturities, available-for-sale, at fair value (amortized cost of $54,478 and $53,805)	4,506		3,937
Collateralized Loan Obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, at fair value, amortized cost	3,368		3,237
Allowance for credit losses, fixed maturity, AFS	0		0
Gross Unrealized Gains, fixed maturities, available-for-sale	11		13
Gross Unrealized Losses, fixed maturities, available-for-sale	0		0
Fixed maturities, available-for-sale, at fair value (amortized cost of $54,478 and $53,805)	3,379		3,250
CMBS
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, at fair value, amortized cost	2,652		2,976
Allowance for credit losses, fixed maturity, AFS	(14)	$ (14)	(13)	(13)	(13)	(12)
Gross Unrealized Gains, fixed maturities, available-for-sale	25		21
Gross Unrealized Losses, fixed maturities, available-for-sale	(165)		(248)
Fixed maturities, available-for-sale, at fair value (amortized cost of $54,478 and $53,805)	2,498		2,736
Corporate
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, at fair value, amortized cost	23,276		21,555
Allowance for credit losses, fixed maturity, AFS	0		(3)	$ (3)	$ (6)	$ (9)
Gross Unrealized Gains, fixed maturities, available-for-sale	389		117
Gross Unrealized Losses, fixed maturities, available-for-sale	(586)		(1,033)
Fixed maturities, available-for-sale, at fair value (amortized cost of $54,478 and $53,805)	23,079		20,636
Foreign Govt./Govt. Agencies
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, at fair value, amortized cost	403		500
Allowance for credit losses, fixed maturity, AFS	0		0
Gross Unrealized Gains, fixed maturities, available-for-sale	9		3
Gross Unrealized Losses, fixed maturities, available-for-sale	(3)		(23)
Fixed maturities, available-for-sale, at fair value (amortized cost of $54,478 and $53,805)	409		480
Municipal
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, at fair value, amortized cost	4,690		5,574
Allowance for credit losses, fixed maturity, AFS	0		0
Gross Unrealized Gains, fixed maturities, available-for-sale	82		77
Gross Unrealized Losses, fixed maturities, available-for-sale	(291)		(347)
Fixed maturities, available-for-sale, at fair value (amortized cost of $54,478 and $53,805)	4,481		5,304
RMBS
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, at fair value, amortized cost	6,000		5,610
Allowance for credit losses, fixed maturity, AFS	0		0
Gross Unrealized Gains, fixed maturities, available-for-sale	43		13
Gross Unrealized Losses, fixed maturities, available-for-sale	(265)		(393)
Fixed maturities, available-for-sale, at fair value (amortized cost of $54,478 and $53,805)	5,778		5,230
U.S. Treasuries
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, at fair value, amortized cost	1,192		1,138
Allowance for credit losses, fixed maturity, AFS	0		0
Gross Unrealized Gains, fixed maturities, available-for-sale	6		0
Gross Unrealized Losses, fixed maturities, available-for-sale	(125)		(144)
Fixed maturities, available-for-sale, at fair value (amortized cost of $54,478 and $53,805)	$ 1,073		$ 994