POLICY LIABILITIES - Summary of Undiscounted Expected Future Gross Premiums and Future Benefits and Expenses (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	$ 153,700	$ 156,494
Benefits and Expenses	188,244	193,058
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	57,471	59,169
Benefits and Expenses	63,270	66,427
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	37,282	38,583
Benefits and Expenses	38,763	39,884
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	12,133	12,677
Benefits and Expenses	41,545	42,541
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	2,922	2,719
Benefits and Expenses	3,488	3,260
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	8,977	9,095
Benefits and Expenses	4,694	4,548
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	5,748	5,776
Benefits and Expenses	3,109	3,177
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	19,775	19,886
Benefits and Expenses	20,421	20,626
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	4,911	4,922
Benefits and Expenses	3,023	3,025
Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	1,124	1,162
Benefits and Expenses	682	726
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	1,665	1,781
Benefits and Expenses	7,232	7,448
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	1,692	724
Benefits and Expenses	$ 2,017	$ 1,396