POLICY LIABILITIES - Summary of Undiscounted Expected Future Gross Premiums and Future Benefits and Expenses (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	$ 156,494	$ 171,593
Benefits and Expenses	193,058	209,402
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	59,169	65,454	[1]
Benefits and Expenses	66,427	73,009	[1]
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	38,583	43,954	[1]
Benefits and Expenses	39,884	44,005	[1]
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	12,677	14,685	[1]
Benefits and Expenses	42,541	46,166	[1]
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	2,719	2,375
Benefits and Expenses	3,260	2,787
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	9,095	9,481
Benefits and Expenses	4,548	4,636
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	5,776	5,858
Benefits and Expenses	3,177	3,267
Critical care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	19,886	21,069
Benefits and Expenses	20,626	22,113
Hospital indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	4,922	5,164
Benefits and Expenses	3,025	3,338
Dental/vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	1,162	1,208
Benefits and Expenses	726	759
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	1,781	2,012	[1]
Benefits and Expenses	7,448	8,175	[1]
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	724	333
Benefits and Expenses	$ 1,396	$ 1,147

[1] Prior-year amounts reflect the immaterial revision of amounts disclosed in the Company's Quarterly Reports on Form 10-Q for 2023 to correctly apply the yen/dollar exchange rate in effect for the period presented.