POLICY LIABILITIES - Summary of Interest Expense Related to Insurance Contracts Recognized (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	$ 559	$ 576
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	233	246
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	66	65
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	114	118
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	11	10
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	7	6
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	7	8
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	85	85
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	9	9
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	18	19
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	$ 6	$ 7