BUSINESS SEGMENT INFORMATION - Operations by Segment - Assets (Detail) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 147,046	$ 157,542
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	119,270	128,536
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	21,944	23,106
Corporate and other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 5,832	$ 5,900