BUSINESS SEGMENT INFORMATION - Operations by Segment - Assets (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 127,766	$ 118,256
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	107,153	97,646
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	19,413	18,537
Other business segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	216	188
Total Business Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	126,782	116,371
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	25,627	23,375
Intercompany eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ (24,643)	$ (21,490)