POLICY LIABILITIES - Summary of Interest Expense Related to Insurance Contracts Recognized (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	$ 568	$ 563	$ 1,838	$ 1,929
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	243	242	804	868
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	63	59	206	210
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	115	112	378	397
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	8	9	27	26
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	6	6	18	18
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	8	9	26	27
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	86	87	259	259
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	10	11	30	31
Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	3	3	9	10
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	19	18	61	63
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	$ 7	$ 7	$ 20	$ 20