BUSINESS SEGMENT INFORMATION - Operations by Segment - Assets (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 127,253	$ 121,307
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	107,480	102,973
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	17,308	16,112
Other business segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	141	155
Total Business Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	124,929	119,240
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	22,918	19,909
Intercompany eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ (20,594)	$ (17,842)