BUSINESS SEGMENT INFORMATION AND SELECTED FOREIGN CURRENCY TRANSLATION ITEMS - Operations by Segment - Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 116,470	$ 117,566
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	88,537	90,210
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	22,317	21,930
Corporate and other
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 5,616	$ 5,426