POLICY LIABILITIES - Summary of Net Earned Premiums Recognized (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Liability for Future Policy Benefit, Activity [Line Items]
Reinsurance ceded	$ (104)	$ (117)
Net earned premiums	3,688	4,079
Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	2,170	2,625
Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	1,428	1,413
Corporate and other
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	90	42
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	1,132	1,336
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	689	828
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	399	524
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	115	99
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	329	337
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	309	296
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	443	446
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	184	185
Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	53	49
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	39	44
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	$ 10	$ 10