BUSINESS SEGMENT INFORMATION - Operations by Segment - Pretax Earnings (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings	$ 1,047	$ 1,194	$ 3,409	$ 3,600
Realized investment gains (losses)	22	286	379	(177)
Earnings before income taxes	1,069	1,480	3,788	3,423
Income taxes applicable to pretax operating earnings	360	363	1,173	1,200
Effect of foreign currency translation on operating earnings	(97)	2	(271)	28
Aflac Japan
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings	846	994	2,775	2,998
Aflac U.S.
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings	269	260	833	789
Total Business Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings	1,115	1,254	3,608	3,787
Interest expense, noninsurance operations
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings	(50)	(45)	(147)	(134)
Corporate and eliminations
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings	$ (18)	$ (15)	$ (52)	$ (53)