POLICY LIABILITIES - Summary of Net Earned Premiums 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]
Net earned premiums	$ 3,325	$ 3,573	$ 6,781	$ 7,262
Reinsurance ceded	(66)	(103)	(135)	(210)
Corporate and other
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	155	84	320	175
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	832	1,054	1,710	2,149
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	570	672	1,175	1,377
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	316	390	655	812
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	141	115	279	228
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	316	322	641	652
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	332	318	665	627
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	441	439	885	882
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	182	182	367	367
Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	46	53	105	107
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	35	38	69	77
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	$ 25	$ 9	$ 45	$ 19