BUSINESS SEGMENT INFORMATION - Operations by Segment - Assets (Detail) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 124,742	$ 126,724
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	98,189	101,541
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	21,850	21,861
Corporate and other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 4,703	$ 3,322