POLICY LIABILITIES - Reconciliation of Future Policy Benefits (Details) - USD ($) $ in Millions		Sep. 30, 2025	Dec. 31, 2024
Liability for Future Policy Benefit, Activity [Line Items]
Future policy benefits		$ 67,143	$ 70,381
Deferred reinsurance gain liability		148	146
Intercompany eliminations
Liability for Future Policy Benefit, Activity [Line Items]
Future policy benefits	[1]	(5,485)	(5,760)
Aflac Japan
Liability for Future Policy Benefit, Activity [Line Items]
Deferred profit liability		2,135	1,844
Deferred reinsurance gain liability		834	806
Aflac Japan | Cancer
Liability for Future Policy Benefit, Activity [Line Items]
Future policy benefits		24,972	26,597
Aflac Japan | Medical and other health
Liability for Future Policy Benefit, Activity [Line Items]
Future policy benefits		8,046	8,789
Aflac Japan | Life insurance
Liability for Future Policy Benefit, Activity [Line Items]
Future policy benefits		17,839	19,109
Aflac Japan | Other
Liability for Future Policy Benefit, Activity [Line Items]
Future policy benefits		3,223	3,379
Aflac U.S. | Life insurance
Liability for Future Policy Benefit, Activity [Line Items]
Future policy benefits		1,038	938
Aflac U.S. | Accident
Liability for Future Policy Benefit, Activity [Line Items]
Future policy benefits		671	630
Aflac U.S. | Disability
Liability for Future Policy Benefit, Activity [Line Items]
Future policy benefits		661	695
Aflac U.S. | Critical Care
Liability for Future Policy Benefit, Activity [Line Items]
Future policy benefits		6,949	6,800
Aflac U.S. | Hospital Indemnity
Liability for Future Policy Benefit, Activity [Line Items]
Future policy benefits		788	775
Aflac U.S. | Dental/Vision
Liability for Future Policy Benefit, Activity [Line Items]
Future policy benefits		240	245
Aflac U.S. | Other
Liability for Future Policy Benefit, Activity [Line Items]
Future policy benefits		481	462
Corporate and other
Liability for Future Policy Benefit, Activity [Line Items]
Future policy benefits		$ 4,751	$ 5,072

[1] Elimination entry necessary due to the internal reinsurance transactions with Aflac Re and to recapture a portion of policy liabilities ceded externally as a result of the reinsurance retrocession transaction. See Note 8 of the Notes to the Consolidated Financial Statements in the 2024 Annual Report.