BUSINESS SEGMENT AND FOREIGN INFORMATION - Operations by Segment - Assets (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 119,767	$ 121,307	$ 131,094
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	98,525	102,973	113,678
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	18,383	16,112	16,122
Other business segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	128	155	154
Total Business Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	117,036	119,240	129,954
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	24,636	19,909	20,318
Intercompany eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ (21,905)	$ (17,842)	$ (19,178)