BUSINESS SEGMENT INFORMATION - Operations by Segment - Assets (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 123,292	$ 121,307
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	104,614	102,973
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	16,772	16,112
Other business segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	154	155
Total Business Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	121,540	119,240
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	20,949	19,909
Intercompany eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ (19,197)	$ (17,842)