POLICY LIABILITIES - Summary of Net Earned Premiums Recognized (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	[1]	$ 3,476	$ 3,535	$ 10,737	$ 11,379
Reinsurance ceded		(99)	(99)	(309)	(321)
Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	[1]	1,973	2,125	6,207	7,084
Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums		1,419	1,375	4,272	4,182
Corporate and other
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums		83	35	258	112
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums		1,004	1,106	3,154	3,640
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums		640	690	2,018	2,253
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums		371	377	1,183	1,360
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums		122	99	351	297
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums		320	324	973	990
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums		315	293	941	882
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums		436	434	1,317	1,319
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums		180	178	547	546
Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums		53	50	160	148
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums		38	39	113	124
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums		$ 13	$ 9	$ 31	$ 29

[1] Includes a gain (loss) of $22 and $(41) for the three-month periods and $22 and $(42) for the nine-month periods ended September 30, 2023 and 2022, respectively, related to remeasurement of the deferred profit liability for limited-payment contracts.