POLICY LIABILITIES - Summary of Discounted Expected Future Gross Premiums and Future Benefits and Expenses (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023	Dec. 31, 2022
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	$ 105,979	$ 121,753
Benefits and Expenses	112,297	132,131
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	40,474	48,363
Benefits and Expenses	41,548	50,161	$ 54,766
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	25,392	30,757
Benefits and Expenses	20,695	25,257	27,419
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	9,226	11,240
Benefits and Expenses	24,370	29,731	31,954
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	1,968	1,914
Benefits and Expenses	1,768	1,764	1,526
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	6,184	6,369
Benefits and Expenses	3,020	3,109	3,098
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	4,434	4,488
Benefits and Expenses	2,405	2,422	2,445
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	12,076	12,417
Benefits and Expenses	10,847	11,290	11,489
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	3,369	3,419
Benefits and Expenses	1,907	1,943	2,074
Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	780	807
Benefits and Expenses	468	478	488
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	1,250	1,512
Benefits and Expenses	4,244	5,178	5,582
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	826	467
Benefits and Expenses	$ 1,025	$ 798	$ 622