POLICY LIABILITIES - Summary of Discounted Expected Future Gross Premiums and Future Benefits and Expenses (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	$ 121,753	$ 132,451
Benefits and Expenses	132,131	141,463
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	48,363	53,278
Benefits and Expenses	50,161	54,766	$ 72,747
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	30,757	34,693
Benefits and Expenses	25,257	27,419	36,021
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	11,240	12,951
Benefits and Expenses	29,731	31,954	42,720
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	1,914	1,663
Benefits and Expenses	1,764	1,526	1,843
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	6,369	6,510
Benefits and Expenses	3,109	3,098	3,949
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	4,488	4,468
Benefits and Expenses	2,422	2,445	2,871
Critical care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	12,417	12,659
Benefits and Expenses	11,290	11,489	15,388
Hospital indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	3,419	3,483
Benefits and Expenses	1,943	2,074	2,552
Dental/vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	807	821
Benefits and Expenses	478	488	616
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	1,512	1,697
Benefits and Expenses	5,178	5,582	7,322
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	467	228
Benefits and Expenses	$ 798	$ 622	$ 837