POLICY LIABILITIES - Summary of Interest Expense Related to Insurance Contracts 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]
Interest expense	$ 629	$ 654	$ 1,270	$ 1,367
Net earned premiums, principally supplemental health insurance	3,573	3,764	7,262	7,844
Reinsurance ceded	(103)	(105)	(210)	(221)
Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums, principally supplemental health insurance	2,064	2,334	4,234	4,959
Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums, principally supplemental health insurance	1,425	1,394	2,853	2,807
Corporate and other
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums, principally supplemental health insurance	84	36	175	82
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	276	296	561	626
Net earned premiums, principally supplemental health insurance	1,054	1,193	2,149	2,528
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	72	73	143	151
Net earned premiums, principally supplemental health insurance	672	735	1,377	1,563
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	130	136	263	285
Net earned premiums, principally supplemental health insurance	390	459	812	983
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	10	8	19	17
Net earned premiums, principally supplemental health insurance	115	99	228	197
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	6	5	12	12
Net earned premiums, principally supplemental health insurance	322	329	652	665
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	10	9	18	19
Net earned premiums, principally supplemental health insurance	318	295	627	591
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	86	86	173	172
Net earned premiums, principally supplemental health insurance	439	439	882	885
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	10	10	20	20
Net earned premiums, principally supplemental health insurance	182	183	367	368
Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	3	3	6	7
Net earned premiums, principally supplemental health insurance	53	50	107	99
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	20	21	42	45
Net earned premiums, principally supplemental health insurance	38	42	77	85
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Interest expense	6	7	13	13
Net earned premiums, principally supplemental health insurance	$ 9	$ 9	$ 19	$ 19