POLICY LIABILITIES - Schedule of Other Policyholders' Funds by Guaranteed Crediting Rates (Detail) - USD ($) $ in Millions	Dec. 31, 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	$ 5,939	$ 6,423	$ 7,410
Cash Surrender Value	$ 5,850	$ 6,326
Lower Limit | Aflac Japan | Fixed Annuity
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Guaranteed Minimum Crediting Rates	0.50%	0.50%
Upper Limit | Aflac Japan | Fixed Annuity
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]
Guaranteed Minimum Crediting Rates	2.30%	2.30%