POLICY LIABILITIES - Schedule of Changes in Other Policyholders' Funds (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2024	Dec. 31, 2023
Policyholder Account Balance [Line Items]
Other deposit type reserves		$ 293	$ 230
Total		5,831	6,169
Aflac Japan | Fixed Annuity
Policyholder Account Balance [Line Items]
Beginning balance	[1]	5,939	6,423
Premiums received	[1]	29	126
Transfers from WAYS conversions	[1]	61	229
Surrenders and withdrawals	[1]	(18)	(59)
Benefit payments	[1]	(110)	(419)
Interest credited	[1]	13	53
Foreign currency translation and other	[1]	(376)	(414)
Ending balance	[1]	$ 5,538	$ 5,939

[1] Aflac Japan fixed annuities