POLICY LIABILITIES - Summary of Interest Expense Related to Insurance Contracts Recognized (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	$ 603	$ 568	$ 1,744	$ 1,838
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	257	243	740	804
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	71	63	202	206
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	123	115	355	378
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	11	8	31	27
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	7	6	20	18
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	9	8	25	26
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	85	86	256	259
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	10	10	29	30
Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	3	3	9	9
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	20	19	57	61
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	$ 7	$ 7	$ 20	$ 20