BUSINESS SEGMENT INFORMATION - Operations by Segment - Pretax Earnings (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings		$ 995	$ 1,157	$ 2,030	$ 2,326
Realized investment gains (losses), non-operating	[1]	104	92	100	36
Other non-operating income (loss)		(225)	(11)	(243)	(20)
Earnings before income taxes		874	1,238	1,887	2,342
Income taxes applicable to pretax operating earnings		344	400	701	795
Effect of foreign currency translation on operating earnings		(59)	(13)	(117)	(61)
Gain (loss) on change in fair value of derivative, interest rate component, operating		23	10	40	20
Gain (Loss) on Investments		127	102	140	56
Aflac Japan
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings		757	927	1,576	1,860
Aflac U.S.
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings		293	300	578	603
Other business segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings		3	0	4	0
Total Business Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings		1,053	1,227	2,158	2,463
Interest expense, noninsurance operations
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings		(38)	(51)	(87)	(101)
Corporate and eliminations
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings		$ (20)	$ (19)	$ (41)	$ (36)

[1] Excluding a gain of $23 and $10 for the three-month periods and $40 and $20 for the six-month periods ended June 30, 2015, and 2014, respectively, 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