INCOME TAXES - Components of Income Tax Expense (Benefit) Applicable to Pretax Earnings (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Reconciliation of Provision of Income Taxes [Line Items]
Current	$ 1,115	$ 1,330	$ 1,663
Deferred	(228)	(356)	(1,060)
Income tax expense (benefit)	887	974	603
Aflac Japan
Reconciliation of Provision of Income Taxes [Line Items]
Current	785	1,196	1,275
Deferred	217	159	(160)
Income tax expense (benefit)	1,002	1,355	1,115
Aflac U.S.
Reconciliation of Provision of Income Taxes [Line Items]
Current	330	134	388
Deferred	(445)	(515)	(900)
Income tax expense (benefit)	$ (115)	$ (381)	$ (512)