POLICY LIABILITIES - Summary of Undiscounted Expected Future Gross Premiums and Future Benefits and Expenses (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	$ 142,128	$ 156,494
Benefits and Expenses	173,563	193,058
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	51,506	59,169
Benefits and Expenses	57,838	66,427
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	33,233	38,583
Benefits and Expenses	34,968	39,884
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	10,707	12,677
Benefits and Expenses	36,842	42,541
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	2,865	2,719
Benefits and Expenses	3,432	3,260
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	9,047	9,095
Benefits and Expenses	4,533	4,548
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	5,811	5,776
Benefits and Expenses	3,213	3,177
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	19,966	19,886
Benefits and Expenses	20,670	20,626
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	4,964	4,922
Benefits and Expenses	3,055	3,025
Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	1,154	1,162
Benefits and Expenses	729	726
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	1,523	1,781
Benefits and Expenses	6,467	7,448
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	1,352	724
Benefits and Expenses	$ 1,816	$ 1,396