BUSINESS SEGMENT INFORMATION - Operations by Segment - Assets (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 121,401	$ 119,767
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	99,102	98,525
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	18,770	18,383
Other business segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	144	128
Total Business Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	118,016	117,036
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	25,736	24,636
Intercompany eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ (22,351)	$ (21,905)