BUSINESS SEGMENT INFORMATION - Operations by Segment - Pretax Earnings (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings	$ 1,041		$ 1,047	$ 3,367		$ 3,409
Realized investment gains (losses), non-operating	6	[1]	22	42	[1]	379
Other non-operating income (loss)	27		0	7		0
Earnings before income taxes	1,074		1,069	3,416		3,788
Income taxes applicable to pretax operating earnings	356		360	1,151		1,173
Effect of foreign currency translation on operating earnings	(19)		(97)	(80)		(271)
Gain (loss) on change in fair value of derivative, interest rate component, operating	10			30
Aflac Japan
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings	828		846	2,688		2,775
Aflac U.S.
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings	269		269	872		833
Total Business Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings	1,097		1,115	3,560		3,608
Interest expense, noninsurance operations
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings	(49)		(50)	(150)		(147)
Corporate and eliminations
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings	$ (7)		$ (18)	$ (43)		$ (52)

[1] Excluding a gain of $10 for the three-month period and $30 for the nine-month period ended September 30, 2014 related to the interest rate component of the change in fair value of foreign currency swaps on notes payable which is classified as an operating gain when analyzing segment operations