BUSINESS SEGMENT INFORMATION - Operations by Segment - Assets (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 119,918	$ 131,094
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	101,471	113,678
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	16,135	16,122
Other business segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	153	154
Total Business Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	117,759	129,954
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	19,821	20,318
Intercompany eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ (17,662)	$ (19,178)