POLICY LIABILITIES - Summary of Interest Expense Related to Insurance Contracts Recognized (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	$ 576	$ 641
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	246	285
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	65	71
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	118	133
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	10	9
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	6	6
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	8	8
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	85	87
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	9	10
Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	3	3
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	19	22
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	$ 7	$ 7