POLICY LIABILITIES - Summary of Net Earned Premiums Recognized (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	$ 3,328	$ 3,476	$ 10,109	$ 10,737
Reinsurance ceded	(71)	(99)	(206)	(309)
Corporate and other
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	160	83	479	258
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	885	1,004	2,595	3,154
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	577	640	1,752	2,018
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	251	371	906	1,183
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	141	122	420	351
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	314	320	955	973
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	333	315	998	941
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	439	436	1,324	1,317
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	181	180	548	547
Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	54	53	159	160
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	35	38	104	113
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	$ 29	$ 13	$ 75	$ 31