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INVESTMENTS - Schedule of Amortized Cost, Allowance for Credit Losses, Gross Unrealized Appreciation/(Depreciation) and Fair Value of Fixed Maturity Securities (Details) - USD ($) $ in Millions	Jun. 30, 2026	Mar. 31, 2026	Dec. 31, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024
Fixed maturity securities - available for sale
Amortized Cost	$ 21,451		$ 21,032
Allowance for Credit Losses	(64)	$ (53)	(68)	$ (40)	$ (37)	$ (36)
Unrealized Appreciation	164		337
Unrealized Depreciation	(399)		(322)
Fair Value	21,152		20,978
Fixed maturity securities – held to maturity
Amortized Cost	576		573
Allowance for Credit Losses	(8)	(8)	(6)	(7)	(8)	(8)
Unrealized Appreciation	10		18
Unrealized Depreciation	(11)		(9)
Fair Value	568		576
U.S. Treasury securities and obligations of U.S. government agencies and corporations
Fixed maturity securities - available for sale
Amortized Cost	294		292
Allowance for Credit Losses	0		0
Unrealized Appreciation	0		0
Unrealized Depreciation	(6)		(5)
Fair Value	288		287
Tax-exempt obligations of U.S. states and political subdivisions
Fixed maturity securities - available for sale
Amortized Cost	40		45
Allowance for Credit Losses	0		0
Unrealized Appreciation	0		0
Unrealized Depreciation	(4)		(4)
Fair Value	37		41
Corporate securities
Fixed maturity securities - available for sale
Amortized Cost	6,367		6,315
Allowance for Credit Losses	(39)	(39)	(54)	(39)	(36)	(35)
Unrealized Appreciation	61		138
Unrealized Depreciation	(119)		(98)
Fair Value	6,270		6,301
Fixed maturity securities – held to maturity
Amortized Cost	180		166
Allowance for Credit Losses	(2)	(2)	(2)	(2)	(2)	(2)
Unrealized Appreciation	1		7
Unrealized Depreciation	(3)		(1)
Fair Value	176		169
Asset-backed securities
Fixed maturity securities - available for sale
Amortized Cost	4,604		4,571
Allowance for Credit Losses	(25)	(14)	(14)	0	0	0
Unrealized Appreciation	6		12
Unrealized Depreciation	(27)		(15)
Fair Value	4,558		4,554
Fixed maturity securities – held to maturity
Amortized Cost	318		328
Allowance for Credit Losses	(5)	(5)	(3)	(4)	(4)	(4)
Unrealized Appreciation	4		5
Unrealized Depreciation	(8)		(8)
Fair Value	310		322
Agency commercial
Fixed maturity securities - available for sale
Amortized Cost	403		404
Allowance for Credit Losses	0		0
Unrealized Appreciation	5		9
Unrealized Depreciation	(3)		(2)
Fair Value	405		412
Non-agency commercial
Fixed maturity securities - available for sale
Amortized Cost	841		739
Allowance for Credit Losses	0		0
Unrealized Appreciation	1		1
Unrealized Depreciation	(24)		(22)
Fair Value	818		718
Agency residential
Fixed maturity securities - available for sale
Amortized Cost	3,655		3,794
Allowance for Credit Losses	0		0
Unrealized Appreciation	34		67
Unrealized Depreciation	(108)		(95)
Fair Value	3,581		3,766
Non-agency residential
Fixed maturity securities - available for sale
Amortized Cost	1,658		1,557
Allowance for Credit Losses	0		0
Unrealized Appreciation	12		31
Unrealized Depreciation	(9)		(1)
Fair Value	1,661		1,587
Commercial
Fixed maturity securities – held to maturity
Amortized Cost	0		0
Allowance for Credit Losses	0		0
Unrealized Appreciation	0		0
Unrealized Depreciation	0		0
Fair Value	0		0
Foreign government securities
Fixed maturity securities - available for sale
Amortized Cost	1,068		1,041
Allowance for Credit Losses	0		0
Unrealized Appreciation	11		18
Unrealized Depreciation	(38)		(29)
Fair Value	1,041		1,030
Foreign corporate securities
Fixed maturity securities - available for sale
Amortized Cost	2,521		2,274
Allowance for Credit Losses	0		0
Unrealized Appreciation	35		60
Unrealized Depreciation	(61)		(50)
Fair Value	2,494		2,284
Fixed maturity securities – held to maturity
Amortized Cost	78		79
Allowance for Credit Losses	(1)	$ (1)	(1)	$ (1)	$ (1)	$ (1)
Unrealized Appreciation	5		6
Unrealized Depreciation	0		0
Fair Value	$ 82		$ 84