POLICY LIABILITIES - Summary of Interest Expense Related to Insurance Contracts Recognized (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	$ 576	$ 565	$ 1,135	$ 1,141
Aflac Japan \| Cancer
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	241	237	474	483
Aflac Japan \| Medical and other health
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	69	66	135	131
Aflac Japan \| Life insurance
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	116	114	230	232
Aflac Japan \| Other
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	20	18	38	37
Aflac U.S. \| Life insurance
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	12	10	23	20
Aflac U.S. \| Accident
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	6	7	13	13
Aflac U.S. \| Disability
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	8	8	15	16
Aflac U.S. \| Critical Care
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	85	86	170	171
Aflac U.S. \| Hospital Indemnity
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	10	10	19	19
Aflac U.S. \| Dental/Vision
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	3	3	6	6
Aflac U.S. \| Other
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	$ 6	$ 6	$ 12	$ 13