POLICY LIABILITIES - Summary of Undiscounted Expected Future Gross Premiums and Future Benefits and Expenses (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	$ 183,998	$ 191,005
Benefits and Expenses	230,333	235,775
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	73,299	75,529
Benefits and Expenses	82,368	84,246
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	48,031	50,720
Benefits and Expenses	49,223	50,778
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	15,926	16,946
Benefits and Expenses	52,692	53,271
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	2,692	2,375
Benefits and Expenses	3,208	2,787
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	9,246	9,481
Benefits and Expenses	4,595	4,636
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	5,800	5,858
Benefits and Expenses	3,215	3,267
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	20,099	21,069
Benefits and Expenses	20,748	22,113
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	5,005	5,164
Benefits and Expenses	3,058	3,338
Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	1,168	1,208
Benefits and Expenses	726	759
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	2,223	2,322
Benefits and Expenses	9,249	9,433
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	509	333
Benefits and Expenses	$ 1,251	$ 1,147