POLICY LIABILITIES - Summary of Undiscounted Expected Future Gross Premiums and Future Benefits and Expenses (Detail) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	$ 142,653	$ 156,494
Benefits and Expenses	173,393	193,058
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	51,712	59,169
Benefits and Expenses	56,881	66,427
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	33,250	38,583
Benefits and Expenses	34,864	39,884
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	10,915	12,677
Benefits and Expenses	37,520	42,541
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	2,966	2,719
Benefits and Expenses	3,559	3,260
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	8,862	9,095
Benefits and Expenses	4,687	4,548
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	5,727	5,776
Benefits and Expenses	3,094	3,177
Critical care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	19,624	19,886
Benefits and Expenses	20,340	20,626
Hospital indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	4,859	4,922
Benefits and Expenses	3,017	3,025
Dental/vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	1,118	1,162
Benefits and Expenses	679	726
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	1,477	1,781
Benefits and Expenses	6,479	7,448
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	2,143	724
Benefits and Expenses	$ 2,273	$ 1,396