POLICY LIABILITIES - Summary of Interest Expense Related to Insurance Contracts Recognized (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	$ 528	$ 576	$ 1,065	$ 1,135
Aflac Japan \| Cancer
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	214	241	431	474
Aflac Japan \| Medical and other health
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	65	69	131	135
Aflac Japan \| Life insurance
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	104	116	212	230
Aflac Japan \| Other
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	18	20	36	38
Aflac U.S. \| Life insurance
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	13	12	25	23
Aflac U.S. \| Accident
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	7	6	14	13
Aflac U.S. \| Disability
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	7	8	14	15
Aflac U.S. \| Critical care
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	84	85	167	170
Aflac U.S. \| Hospital indemnity
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	8	10	18	19
Aflac U.S. \| Dental/vision
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	2	3	5	6
Aflac U.S. \| Other
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	$ 6	$ 6	$ 12	$ 12