POLICY LIABILITIES - Summary of Net Earned Premiums Recognized (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Liability for Future Policy Benefit, Activity [Line Items]
Reinsurance ceded	$ (103)	$ (105)	$ (210)	$ (221)
Net earned premiums	3,573	3,764	7,262	7,844
Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	2,064	2,334	4,234	4,959
Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	1,425	1,394	2,853	2,807
Corporate and other
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	84	36	175	82
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	1,054	1,193	2,149	2,528
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	672	735	1,377	1,563
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	390	459	812	983
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	115	99	228	197
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	322	329	652	665
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	318	295	627	591
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	439	439	882	885
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	182	183	367	368
Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	53	50	107	99
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	38	42	77	85
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	$ 9	$ 9	$ 19	$ 19