INVESTMENTS - Summary of Amortized Cost, Allowance for Credit Losses, Gross Unrealized Appreciation/(Depreciation) and Fair Value of Fixed Maturity Securities (Details) - USD ($) $ in Millions	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
Fixed maturity securities – available for sale
Amortized Cost	$ 15,141		$ 13,699
Allowances for Credit Losses	(57)	$ (56)	(46)	$ (27)	$ (29)	$ (27)
Unrealized Appreciation	37		30
Unrealized Depreciation	(919)		(1,013)
Fair Value	14,202		12,671
Fixed maturity securities – held to maturity
Amortized Cost	796		820
Allowances for Credit Loss	(8)	(9)	(9)
Unrealized Appreciation	4		3
Unrealized Depreciation	(21)		(22)
Fair Value	771		793
U.S. Treasury securities and obligations of U.S. government agencies and corporations
Fixed maturity securities – available for sale
Amortized Cost	475		575
Allowances for Credit Losses	0		0
Unrealized Appreciation	0		0
Unrealized Depreciation	(37)		(40)
Fair Value	439		535
Obligations of U.S. states and political subdivisions
Fixed maturity securities – available for sale
Amortized Cost	424		444
Allowances for Credit Losses	0		0
Unrealized Appreciation	1		2
Unrealized Depreciation	(30)		(32)
Fair Value	395		413
Corporate Securities
Fixed maturity securities – available for sale
Amortized Cost	4,552		3,913
Allowances for Credit Losses	(55)	(55)	(45)	(26)	(20)	(19)
Unrealized Appreciation	21		14
Unrealized Depreciation	(309)		(322)
Fair Value	4,209		3,561
Fixed maturity securities – held to maturity
Amortized Cost	152		152
Allowances for Credit Loss	(2)	(2)	(2)
Unrealized Appreciation	0		0
Unrealized Depreciation	(6)		(6)
Fair Value	144		144
Asset Backed Securities
Fixed maturity securities – available for sale
Amortized Cost	4,783		4,111
Allowances for Credit Losses	0	0	0	0	(8)	(8)
Unrealized Appreciation	5		5
Unrealized Depreciation	(111)		(165)
Fair Value	4,676		3,951
Fixed maturity securities – held to maturity
Amortized Cost	603		634
Allowances for Credit Loss	(6)	(6)	(6)
Unrealized Appreciation	2		2
Unrealized Depreciation	(15)		(15)
Fair Value	585		614
Commercial
Fixed maturity securities – available for sale
Amortized Cost	567		569
Allowances for Credit Losses	0		0
Unrealized Appreciation	0		0
Unrealized Depreciation	(63)		(59)
Fair Value	503		509
Fixed maturity securities – held to maturity
Amortized Cost	14		7
Allowances for Credit Loss	0		0
Unrealized Appreciation	0		0
Unrealized Depreciation	0		0
Fair Value	13		7
Agency residential
Fixed maturity securities – available for sale
Amortized Cost	1,817		1,792
Allowances for Credit Losses	0		0
Unrealized Appreciation	3		3
Unrealized Depreciation	(166)		(167)
Fair Value	1,654		1,628
Non-agency residential
Fixed maturity securities – available for sale
Amortized Cost	60		3
Allowances for Credit Losses	0		0
Unrealized Appreciation	0		0
Unrealized Depreciation	(1)		0
Fair Value	59		3
Foreign government securities
Fixed maturity securities – available for sale
Amortized Cost	735		696
Allowances for Credit Losses	0		0
Unrealized Appreciation	3		2
Unrealized Depreciation	(53)		(61)
Fair Value	684		637
Foreign Corporate
Fixed maturity securities – available for sale
Amortized Cost	1,729		1,597
Allowances for Credit Losses	(1)	(1)	(1)	$ (2)	$ (1)	$ 0
Unrealized Appreciation	5		4
Unrealized Depreciation	(149)		(167)
Fair Value	1,583		1,433
Fixed maturity securities – held to maturity
Amortized Cost	28		28
Allowances for Credit Loss	(1)	$ (1)	(1)
Unrealized Appreciation	2		2
Unrealized Depreciation	0		0
Fair Value	$ 29		$ 28