POLICY LIABILITIES - Summary of Interest Expense Related to Insurance Contracts Recognized (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	$ 565	$ 629	$ 1,141	$ 1,270
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	237	276	483	561
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	66	72	131	143
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	114	130	232	263
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	10	10	20	19
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	7	6	13	12
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	8	10	16	18
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	86	86	171	173
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	10	10	19	20
Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	3	3	6	6
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	18	20	37	42
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	$ 6	$ 6	$ 13	$ 13