Operations by Segment - Assets (Detail) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 114,720	$ 101,039
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	99,903	87,061
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	14,030	13,095
Other business segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	170	155
Total Business Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	114,103	100,311
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	15,969	14,047
Intercompany eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ (15,352)	$ (13,319)