INVESTMENTS - Net Investment Income (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Mar. 31, 2022	Sep. 30, 2022	Sep. 30, 2023
Net Investment Income [Line Items]
Gross investment income	$ 97	$ 97	$ 103	$ 195	$ 269
Less: investment expenses	(24)	(5)	(4)	(6)	(42)
Net investment income	73	92	99	189	227
Retained Business
Net Investment Income [Line Items]
Gross investment income	79	51		87	209
Less: investment expenses	(23)	(4)		(5)	(39)
Net investment income	56	47		82	170
Ceded Business
Net Investment Income [Line Items]
Gross investment income	18	46		108	60
Less: investment expenses	(1)	(1)		(1)	(3)
Net investment income	17	45		107	57
Fixed maturity securities
Net Investment Income [Line Items]
Gross investment income	71	76	61	156	196
Fixed maturity securities | Retained Business
Net Investment Income [Line Items]
Gross investment income	58	42		78	156
Fixed maturity securities | Ceded Business
Net Investment Income [Line Items]
Gross investment income	13	34		78	40
Equity securities
Net Investment Income [Line Items]
Gross investment income	0	1	1	2	2
Equity securities | Retained Business
Net Investment Income [Line Items]
Gross investment income	0	0		0	0
Equity securities | Ceded Business
Net Investment Income [Line Items]
Gross investment income	0	1		2	2
Mortgage and other loans
Net Investment Income [Line Items]
Gross investment income	6	7	11	18	14
Mortgage and other loans | Retained Business
Net Investment Income [Line Items]
Gross investment income	6	0		0	14
Mortgage and other loans | Ceded Business
Net Investment Income [Line Items]
Gross investment income	0	7		18	0
Other invested assets
Net Investment Income [Line Items]
Gross investment income	15	10	29	14	35
Other invested assets | Retained Business
Net Investment Income [Line Items]
Gross investment income	14	9		9	33
Other invested assets | Ceded Business
Net Investment Income [Line Items]
Gross investment income	1	1		5	2
Short-term investments and cash equivalents
Net Investment Income [Line Items]
Gross investment income	5	3	$ 1	5	22
Short-term investments and cash equivalents | Retained Business
Net Investment Income [Line Items]
Gross investment income	1	0		0	6
Short-term investments and cash equivalents | Ceded Business
Net Investment Income [Line Items]
Gross investment income	$ 4	$ 3		$ 5	$ 16