POLICY LIABILITIES - Schedule of Changes in Other Policyholders' Funds (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Policyholder Account Balance [Line Items]
Other deposit type reserves	$ 230	$ 220
Total	6,169	6,643
Aflac Japan
Policyholder Account Balance [Line Items]
Total	6,169	6,639
Aflac Japan | Fixed Annuity
Policyholder Account Balance [Line Items]
Beginning balance	6,423	7,410
Premiums received	126	150
Transfers from WAYS conversions	229	214
Surrenders and withdrawals	(59)	(52)
Benefit payments	(419)	(367)
Interest credited	53	57
Foreign currency translation and other	(414)	(989)
Ending balance	$ 5,939	$ 6,423