LIABILITIES FOR FUTURE POLICYHOLDER BENEFITS - Schedule of Liability for Future Policy Benefits, Undiscounted and Discounted Expected Gross Premiums and Expected Future Benefits and Expenses (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Term
Liability for Future Policy Benefit, Activity [Line Items]
Expected future benefit payments and expenses (undiscounted)	$ 5,750	$ 5,860
Expected future gross premiums (undiscounted)	6,877	6,956
Expected future benefit payments and expenses (discounted)	3,328	3,466
Expected future gross premiums (discounted)	3,721	3,862
Payout - Legacy
Liability for Future Policy Benefit, Activity [Line Items]
Expected future benefit payments and expenses (undiscounted)	5,530	5,204
Expected future gross premiums (undiscounted)	0	0
Expected future benefit payments and expenses (discounted)	3,682	3,538
Expected future gross premiums (discounted)	0	0
Payout - Non-Legacy
Liability for Future Policy Benefit, Activity [Line Items]
Expected future benefit payments and expenses (undiscounted)	1,414	1,426
Expected future gross premiums (undiscounted)	0	0
Expected future benefit payments and expenses (discounted)	786	812
Expected future gross premiums (discounted)	0	0
Group Pension
Liability for Future Policy Benefit, Activity [Line Items]
Expected future benefit payments and expenses (undiscounted)	654	668
Expected future gross premiums (undiscounted)	0	0
Expected future benefit payments and expenses (discounted)	454	471
Expected future gross premiums (discounted)	0	0
Health
Liability for Future Policy Benefit, Activity [Line Items]
Expected future benefit payments and expenses (undiscounted)	2,278	2,318
Expected future gross premiums (undiscounted)	82	85
Expected future benefit payments and expenses (discounted)	1,415	1,468
Expected future gross premiums (discounted)	$ 64	$ 68