FAIR VALUE OF ASSETS AND LIABILITIES - Changes in Level 3 Assets and Liabilities (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Insurance Liabilities | Retained Business
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	$ 2,342	$ 3,056	$ 2,835	$ 2,941	$ 2,941
Reduction in estimates of ultimate losses	(121)	(354)	(506)	(702)
Increase in estimates of ultimate losses	105	103	213	235
Change in fair value (discount rate)	(137)	(189)	(382)	46
Fee income and paid losses	44	96	73	196
Other	0	(1)	0	(5)
Fair Value, end of period	2,233	2,711	2,233	2,711	2,835
Insurance Liabilities | Ceded Business
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	2,203	2,695	2,168	2,605	2,605
Reduction in estimates of ultimate losses	(96)	(559)	(192)	(625)
Increase in estimates of ultimate losses	59	143	218	210
Change in fair value (discount rate)	(14)	(20)	(45)	56
Fee income and paid losses	1	14	4	27
Other	0	0	0	0
Fair Value, end of period	2,153	2,273	2,153	2,273	2,168
Foreign corporate private securities | Ceded Business
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		0	1	0	0
Total realized and unrealized gains (losses)		0	0	0
Purchases		5	0	5
Sales		0	0	0
Issuances		0	0	0
Settlements		(2)	(1)	(2)
Other		0	0	0
Transfers into Level 3		0	0	0
Transfers out of Level 3		0	0	0
Fair Value, end of period	0	3	0	3	1
Unrealized gains (losses) for assets still held		0	0	0
Short-term investments | Ceded Business
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period			4
Total realized and unrealized gains (losses)			0
Purchases			3
Sales			0
Issuances			0
Settlements			(7)
Other			0
Transfers into Level 3			0
Transfers out of Level 3			0
Fair Value, end of period	0		0		4
Unrealized gains (losses) for assets still held			0
Deposit asset | Ceded Business
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	426	608	438	607	607
Total realized and unrealized gains (losses)	(21)	(10)	(31)	(8)
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Other	(1)	(122)	(3)	(123)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	404	476	404	476	438
Unrealized gains (losses) for assets still held	0	0	0	0
Reinsurance recoverables | Ceded Business
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	155	247	206	235	235
Total realized and unrealized gains (losses)	(4)	(47)	(55)	(35)
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	151	200	151	200	206
Unrealized gains (losses) for assets still held	0	0	0	0
Net modified coinsurance receivable (payable) | Ceded Business
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	(72)	(45)	(78)	18	18
Total realized and unrealized gains (losses)	(56)	(36)	(50)	(99)
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	(128)	(81)	(128)	(81)	(78)
Unrealized gains (losses) for assets still held	0	0	0	0
Fixed maturity securities | U.S. corporate private securities | Retained Business
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	271	182	244	146	146
Total realized and unrealized gains (losses)	(4)	1	(1)	1
Purchases	0	27	24	46
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	(1)
Other	0	0	0	0
Transfers into Level 3	0	18	0	18
Transfers out of Level 3	0	(18)	0	0
Fair Value, end of period	267	210	267	210	244
Unrealized gains (losses) for assets still held	(2)	2	0	1
Fixed maturity securities | U.S. corporate private securities | Ceded Business
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	1		1
Total realized and unrealized gains (losses)	0		0
Purchases	1		1
Sales	0		0
Issuances	0		0
Settlements	0		0
Other	0		0
Transfers into Level 3	0		0
Transfers out of Level 3	0		0
Fair Value, end of period	2		2		1
Unrealized gains (losses) for assets still held	0		0
Fixed maturity securities | Foreign corporate private securities | Retained Business
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	57	36	56	36	36
Total realized and unrealized gains (losses)	(1)	(2)	0	(2)
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	56	34	56	34	56
Unrealized gains (losses) for assets still held	(1)	(3)	0	(2)
Fixed maturity securities | Residential mortgage-backed securities | Retained Business
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	5		5
Total realized and unrealized gains (losses)	0		0
Purchases	0		0
Sales	0		0
Issuances	0		0
Settlements	0		0
Other	0		0
Transfers into Level 3	0		0
Transfers out of Level 3	0		0
Fair Value, end of period	5		5		5
Unrealized gains (losses) for assets still held	0		0
Fixed maturity securities | Asset-backed securities | Retained Business
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	258	191	246	155	155
Total realized and unrealized gains (losses)	0	0	(1)	(2)
Purchases	4	18	18	56
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	(3)	(1)	(4)	(1)
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	259	208	259	208	246
Unrealized gains (losses) for assets still held	0	1	(2)	(1)
Fixed maturity securities | Asset-backed securities | Ceded Business
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	28		0
Total realized and unrealized gains (losses)	0		0
Purchases	0		28
Sales	0		0
Issuances	0		0
Settlements	(2)		(2)
Other	0		0
Transfers into Level 3	0		0
Transfers out of Level 3	(10)		(10)
Fair Value, end of period	16		16		0
Unrealized gains (losses) for assets still held	0		0
Equity securities | Residential mortgage loans | Retained Business
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	348	158	361	161	161
Total realized and unrealized gains (losses)	(2)	0	3	0
Purchases	3	31	7	44
Sales	0	0	0	0
Issuances	0	0	0
Settlements	(44)	(38)	(66)	(54)
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	305	151	305	151	361
Unrealized gains (losses) for assets still held	(4)	0	1	0
Equity securities | Commercial mortgage-backed securities | Retained Business
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	77	48	76	35	35
Total realized and unrealized gains (losses)	0	0	1	0
Purchases	0	30	0	43
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	77	78	77	78	$ 76
Unrealized gains (losses) for assets still held	$ (1)	$ 0	$ 0	$ 0