BUSINESS SEGMENT INFORMATION - Operations by Segment - Assets (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 137,840	$ 116,237
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	120,712	101,692
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	15,785	13,942
Other business segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	144	160
Total Business Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	136,641	115,794
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	21,486	16,182
Intercompany eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ (20,287)	$ (15,739)