BUSINESS SEGMENT AND FOREIGN INFORMATION - Operations by Segment - Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 129,819	$ 118,256	$ 119,727
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	107,858	97,646	98,525
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	19,453	18,537	18,383
Other business segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	270	188	128
Total Business Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	127,581	116,371	117,036
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	26,476	23,375	24,596
Intercompany eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ (24,238)	$ (21,490)	$ (21,905)