POLICY LIABILITIES - Summary of Undiscounted Expected Future Gross Premiums and Future Benefits and Expenses (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	$ 189,737	$ 191,005
Benefits and Expenses	234,636	235,775
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	74,863	75,529
Benefits and Expenses	83,549	84,246
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	50,153	50,720
Benefits and Expenses	50,573	50,778
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	16,690	16,946
Benefits and Expenses	52,993	53,271
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	2,466	2,375
Benefits and Expenses	2,871	2,787
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	9,467	9,481
Benefits and Expenses	4,621	4,636
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	5,889	5,858
Benefits and Expenses	3,286	3,267
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	21,134	21,069
Benefits and Expenses	22,085	22,113
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	5,213	5,164
Benefits and Expenses	3,360	3,338
Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	1,194	1,208
Benefits and Expenses	754	759
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	2,309	2,322
Benefits and Expenses	9,379	9,433
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	359	333
Benefits and Expenses	$ 1,165	$ 1,147