BUSINESS SEGMENT AND FOREIGN INFORMATION - Operations by Segment - Assets (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 131,094	$ 116,237	$ 100,243
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	113,678	101,692	86,487
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	16,122	13,942	12,874
Other business segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	154	160	155
Total Business Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	129,954	115,794	99,516
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	20,318	16,182	13,538
Intercompany eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ (19,178)	$ (15,739)	$ (12,811)