BUSINESS SEGMENT INFORMATION - Operations by Segment - Assets (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 122,209	$ 116,237
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	106,832	101,692
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	14,630	13,942
Other business segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	162	160
Total Business Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	121,624	115,794
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	17,645	16,182
Intercompany eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ (17,060)	$ (15,739)