BUSINESS SEGMENT INFORMATION - Operations by Segment - Assets (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 115,552	$ 116,237
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	100,133	101,692
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	14,207	13,942
Other business segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	159	160
Total Business Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	114,499	115,794
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	18,322	16,182
Intercompany eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ (17,269)	$ (15,739)