POLICY LIABILITIES - Schedule of Changes in Other Policyholders' Funds (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2025	Dec. 31, 2024
Policyholder Account Balance [Line Items]
Other deposit type reserves		$ 293	$ 239
Other policyholders’ funds		5,445	5,460
Aflac Japan
Policyholder Account Balance [Line Items]
Other policyholders’ funds		5,445	5,460
Aflac Japan | Fixed Annuity
Policyholder Account Balance [Line Items]
Beginning balance	[1]	5,221	5,939
Premiums received	[1]	97	104
Transfers from WAYS conversions	[1]	307	249
Surrenders and withdrawals	[1]	(64)	(58)
Benefit payments	[1]	(513)	(446)
Interest credited	[1]	49	49
Foreign currency translation and other	[1]	55	(616)
Ending balance	[1]	$ 5,152	$ 5,221

[1] Aflac Japan fixed annuities