INVESTMENTS - Schedule of Amortized Cost, Allowance for Credit Losses, Gross Unrealized Appreciation/(Depreciation) and Fair Value of Fixed Maturity Securities (Details) - USD ($) $ in Millions	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Fixed maturity securities – available for sale
Amortized Cost	$ 15,520		$ 13,699
Allowances for Credit Losses	(58)	$ (57)	(46)	$ (30)	$ (27)	$ (27)
Unrealized Appreciation	29		30
Unrealized Depreciation	(1,057)		(1,013)
Fair Value	14,434		12,671
Fixed maturity securities – held to maturity
Amortized Cost	791		820
Allowances for Credit Loss	(8)	(8)	(9)	(9)	0	0
Unrealized Appreciation	4		3
Unrealized Depreciation	(27)		(22)
Fair Value	759		793
U.S. Treasury securities and obligations of U.S. government agencies and corporations
Fixed maturity securities – available for sale
Amortized Cost	450		575
Allowances for Credit Losses	0		0
Unrealized Appreciation	0		0
Unrealized Depreciation	(38)		(40)
Fair Value	412		535
Obligations of U.S. states and political subdivisions
Fixed maturity securities – available for sale
Amortized Cost	406		444
Allowances for Credit Losses	(1)	0	0
Unrealized Appreciation	0		2
Unrealized Depreciation	(42)		(32)
Fair Value	363		413
Corporate securities
Fixed maturity securities – available for sale
Amortized Cost	4,577		3,913
Allowances for Credit Losses	(57)	(55)	(45)	(29)	(26)	(19)
Unrealized Appreciation	11		14
Unrealized Depreciation	(371)		(322)
Fair Value	4,160		3,561
Fixed maturity securities – held to maturity
Amortized Cost	156		152
Allowances for Credit Loss	(2)	(2)	(2)	(2)	0	0
Unrealized Appreciation	1		0
Unrealized Depreciation	(9)		(6)
Fair Value	146		144
Asset-backed securities
Fixed maturity securities – available for sale
Amortized Cost	5,029		4,111
Allowances for Credit Losses	0		0	0	0	(8)
Unrealized Appreciation	14		5
Unrealized Depreciation	(63)		(165)
Fair Value	4,980		3,951
Fixed maturity securities – held to maturity
Amortized Cost	595		634
Allowances for Credit Loss	(5)	(6)	(6)	(6)	0	0
Unrealized Appreciation	3		2
Unrealized Depreciation	(18)		(15)
Fair Value	574		614
Commercial
Fixed maturity securities – available for sale
Amortized Cost	626		569
Allowances for Credit Losses	0		0
Unrealized Appreciation	0		0
Unrealized Depreciation	(70)		(59)
Fair Value	556		509
Fixed maturity securities – held to maturity
Amortized Cost	15		7
Allowances for Credit Loss	0		0
Unrealized Appreciation	0		0
Unrealized Depreciation	0		0
Fair Value	15		7
Agency residential
Fixed maturity securities – available for sale
Amortized Cost	1,777		1,792
Allowances for Credit Losses	0		0
Unrealized Appreciation	0		3
Unrealized Depreciation	(240)		(167)
Fair Value	1,537		1,628
Non-agency residential
Fixed maturity securities – available for sale
Amortized Cost	216		3
Allowances for Credit Losses	0		0
Unrealized Appreciation	0		0
Unrealized Depreciation	(9)		0
Fair Value	207		3
Foreign government securities
Fixed maturity securities – available for sale
Amortized Cost	749		696
Allowances for Credit Losses	0		0
Unrealized Appreciation	1		2
Unrealized Depreciation	(66)		(61)
Fair Value	683		637
Foreign corporate securities
Fixed maturity securities – available for sale
Amortized Cost	1,690		1,597
Allowances for Credit Losses	(1)	(1)	(1)	(1)	(2)	0
Unrealized Appreciation	2		4
Unrealized Depreciation	(157)		(167)
Fair Value	1,534		1,433
Fixed maturity securities – held to maturity
Amortized Cost	24		28
Allowances for Credit Loss	(1)	$ (1)	(1)	$ (1)	$ 0	$ 0
Unrealized Appreciation	1		2
Unrealized Depreciation	0		0
Fair Value	$ 24		$ 28