LIABILITIES FOR FUTURE POLICYHOLDER BENEFITS - Policyholder Account Balance (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits	$ 16,507		$ 16,573
Term
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits	1,310		1,341
Payout - Non-Legacy
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits	820		844
Payout - Legacy
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits	3,767		3,620
Group Pension
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits	473		490
Health
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits	1,451		1,505
Operating Segments | Term | Protection Solutions
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Balance, beginning of period	2,125	$ 2,090
Beginning balance at original discount rate	2,051	2,068
Effect of changes in cash flow assumptions			(18)	$ 8
Effect of actual variances from expected experience			(19)	4
Adjusted beginning of period balance			2,014	2,080
Issuances	11	15
Interest accrual	25	25
Net premiums collected	(49)	(51)
Ending Balance at original discount rate	2,001	2,069
Effect of changes in discount rate assumptions	17	81
Balance, end of period	2,018	2,150
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Balance, beginning of period	3,466	3,449
Beginning balance of original discount rate	3,317	3,376
Effect of changes in cash flow assumptions			(20)	9
Effect of actual variances from expected			(23)	5
Adjusted beginning of period balance			3,274	3,390
Issuances	12	16
Interest accrual	41	42
Benefit payments	(63)	(95)
Ending balance at original discount rate	3,264	3,353
Effect of changes in discount rate assumptions	64	162
Balance, end of period	3,328	3,515
Net liability for future policy benefits	1,310	1,365
Less: Reinsurance recoverable	(207)	(206)
Net liability for future policy benefits, after reinsurance recoverable	$ 1,103	$ 1,159
Weighted-average duration of liability for future policyholder benefits (years)	6 years 10 months 24 days	7 years 1 month 6 days
Operating Segments | Payout - Non-Legacy | Non-Legacy
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Balance, beginning of period	$ 0	$ 0
Beginning balance at original discount rate	0	0
Effect of changes in cash flow assumptions			0	0
Effect of actual variances from expected experience			0	0
Adjusted beginning of period balance			0	0
Issuances	0	0
Interest accrual	0	0
Net premiums collected	0	0
Ending Balance at original discount rate	0	0
Effect of changes in discount rate assumptions	0	0
Balance, end of period	0	0
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Balance, beginning of period	844	828
Beginning balance of original discount rate	840	845
Effect of changes in cash flow assumptions			(1)	0
Effect of actual variances from expected			(1)	0
Adjusted beginning of period balance			838	845
Issuances	11	14
Interest accrual	10	10
Benefit payments	(23)	(23)
Ending balance at original discount rate	836	846
Effect of changes in discount rate assumptions	(16)	6
Balance, end of period	820	852
Net liability for future policy benefits	820	853
Less: Reinsurance recoverable	(36)	0
Net liability for future policy benefits, after reinsurance recoverable	$ 784	$ 853
Weighted-average duration of liability for future policyholder benefits (years)	9 years 3 months 18 days	9 years 4 months 24 days
Operating Segments | Payout - Legacy | Legacy
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Balance, beginning of period	$ 0	$ 0
Beginning balance at original discount rate	0	0
Effect of changes in cash flow assumptions			0	0
Effect of actual variances from expected experience			0	0
Adjusted beginning of period balance			0	0
Issuances	0	0
Interest accrual	0	0
Net premiums collected	0	0
Ending Balance at original discount rate	0	0
Effect of changes in discount rate assumptions	0	0
Balance, end of period	0	0
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Balance, beginning of period	3,620	2,689
Beginning balance of original discount rate	3,840	3,024
Effect of changes in cash flow assumptions			0	0
Effect of actual variances from expected			(2)	1
Adjusted beginning of period balance			3,838	3,025
Issuances	269	222
Interest accrual	35	21
Benefit payments	(89)	(65)
Ending balance at original discount rate	4,053	3,203
Effect of changes in discount rate assumptions	(286)	(257)
Balance, end of period	3,767	2,946
Net liability for future policy benefits	3,767	2,945
Less: Reinsurance recoverable	(1,516)	(589)
Net liability for future policy benefits, after reinsurance recoverable	$ 2,251	$ 2,356
Weighted-average duration of liability for future policyholder benefits (years)	7 years 7 months 6 days	7 years 10 months 24 days
Corporate and Other | Group Pension
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Balance, beginning of period	$ 0	$ 0
Beginning balance at original discount rate	0	0
Effect of changes in cash flow assumptions			0	0
Effect of actual variances from expected experience			0	0
Adjusted beginning of period balance			0	0
Issuances	0	0
Interest accrual	0	0
Net premiums collected	0	0
Ending Balance at original discount rate	0	0
Effect of changes in discount rate assumptions	0	0
Balance, end of period	0	0
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Balance, beginning of period	490	523
Beginning balance of original discount rate	536	583
Effect of changes in cash flow assumptions			0	0
Effect of actual variances from expected			1	(1)
Adjusted beginning of period balance			537	582
Issuances	0	0
Interest accrual	5	5
Benefit payments	(16)	(17)
Ending balance at original discount rate	526	570
Effect of changes in discount rate assumptions	(53)	(48)
Balance, end of period	473	522
Net liability for future policy benefits	473	522
Less: Reinsurance recoverable	0	0
Net liability for future policy benefits, after reinsurance recoverable	$ 473	$ 522
Weighted-average duration of liability for future policyholder benefits (years)	7 years	7 years 1 month 6 days
Corporate and Other | Health
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Balance, beginning of period	$ (21)	$ (6)
Beginning balance at original discount rate	(22)	(6)
Effect of changes in cash flow assumptions			0	0
Effect of actual variances from expected experience			1	(6)
Adjusted beginning of period balance			(21)	(12)
Issuances	0	0
Interest accrual	0	0
Net premiums collected	1	1
Ending Balance at original discount rate	(20)	(11)
Effect of changes in discount rate assumptions	1	0
Balance, end of period	(19)	(11)
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Balance, beginning of period	1,484	1,554
Beginning balance of original discount rate	1,672	1,795
Effect of changes in cash flow assumptions			0	0
Effect of actual variances from expected			1	(7)
Adjusted beginning of period balance			$ 1,673	$ 1,788
Issuances	0	0
Interest accrual	14	15
Benefit payments	(41)	(33)
Ending balance at original discount rate	1,646	1,770
Effect of changes in discount rate assumptions	(215)	(198)
Balance, end of period	1,431	1,572
Net liability for future policy benefits	1,451	1,584
Less: Reinsurance recoverable	(1,147)	(1,258)
Net liability for future policy benefits, after reinsurance recoverable	$ 304	$ 326
Weighted-average duration of liability for future policyholder benefits (years)	8 years 7 months 6 days	8 years 8 months 12 days