POLICY LIABILITIES - Summary of Net Earned Premiums Recognized (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	$ 13,440	$ 14,123	$ 14,901
Reinsurance ceded	(284)	(404)	(419)
Corporate and other
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	680	400	145
Cancer | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	3,545	4,063	4,716
Medical and other health | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	2,181	2,631	2,917
Life insurance
Liability for Future Policy Benefit, Activity [Line Items]
Reinsurance ceded	(51)	(52)	(35)
Life insurance | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	1,225	1,532	1,769
Life insurance | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	565	475	396
Accident | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	1,265	1,288	1,317
Disability | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	1,327	1,256	1,179
Critical care | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	1,763	1,749	1,758
Hospital indemnity | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	727	725	725
Dental/vision | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	202	214	199
Other | Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	134	149	161
Other | Aflac U.S.
Liability for Future Policy Benefit, Activity [Line Items]
Net earned premiums	$ 110	$ 45	$ 38