POLICY LIABILITIES - Schedule of Other Policyholders' Funds by Guaranteed Crediting Rates (Details) - USD ($) $ in Millions		Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Policyholder Account Balance, Weighted Average Crediting Rate		1.50%	1.50%
Aflac Japan | Fixed Annuity
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
At Guaranteed Minimum	[1]	$ 5,652	$ 6,423	$ 7,410
Cash Surrender Value	[1]	$ 5,564	$ 6,326
Lower Limit | Aflac Japan | Fixed Annuity
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Guaranteed Minimum Crediting Rates	[1],[2]	0.50%	0.50%
Upper Limit | Aflac Japan | Fixed Annuity
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Guaranteed Minimum Crediting Rates	[1],[2]	2.30%	2.30%

[1] Aflac Japan fixed annuities

[2] Weighted-average crediting rate of 1.5% at September 30, 2023 and December 31, 2022.