BUSINESS SEGMENT INFORMATION - Operations by Segment - Assets (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 116,313	$ 131,094
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	98,710	113,678
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	15,681	16,122
Other business segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	150	154
Total Business Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	114,541	129,954
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	19,872	20,318
Intercompany eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ (18,100)	$ (19,178)