POLICY LIABILITIES - Summary of Undiscounted Expected Future Gross Premiums and Future Benefits and Expenses (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	$ 148,495	$ 142,653
Benefits and Expenses	181,215	173,393
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	54,446	51,712
Benefits and Expenses	59,903	56,881
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	34,739	33,250
Benefits and Expenses	36,751	34,864
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	11,492	10,915
Benefits and Expenses	39,412	37,520
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	3,091	2,966
Benefits and Expenses	3,686	3,559
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	8,843	8,862
Benefits and Expenses	4,673	4,687
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	5,748	5,727
Benefits and Expenses	3,110	3,094
Critical Care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	19,780	19,624
Benefits and Expenses	20,463	20,340
Hospital Indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	4,937	4,859
Benefits and Expenses	3,052	3,017
Dental/Vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	1,117	1,118
Benefits and Expenses	684	679
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	1,538	1,477
Benefits and Expenses	6,790	6,479
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	2,764	2,143
Benefits and Expenses	$ 2,691	$ 2,273