BUSINESS SEGMENT INFORMATION - Operations by Segment - Assets (Detail) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 134,966	$ 131,738
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	108,762	105,734
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	21,385	21,002
Corporate and other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 4,819	$ 5,002