BUSINESS SEGMENT INFORMATION - Operations by Segment - Assets (Detail) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 141,287	$ 118,256
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	120,571	97,646
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	19,712	18,537
Other business segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	248	188
Total Business Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	140,531	116,371
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	28,189	23,375
Intercompany eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ (27,433)	$ (21,490)