BUSINESS SEGMENT INFORMATION - Operations by Segment - Pretax Earnings (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015		Sep. 30, 2016	Sep. 30, 2015
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings		$ 1,147	$ 1,027		$ 3,336	$ 3,058
Realized investment gains (losses), non-operating	[1]	(166)	(136)		(324)	(36)
Other non-operating income (loss)		(18)	(27)	[2]	(98)	(270)	[2],[3]
Earnings before income taxes		963	864		2,914	2,752
Income taxes applicable to pretax operating earnings		399	355		1,154	1,057
Effect of foreign currency translation on operating earnings		61	(58)		110	(175)
Gain (loss) on change in fair value of derivative, interest rate component, operating		20	22		64	62
Gain (Loss) on Investments		(146)	(114)		(260)	26
September Twenty Fifteen Profit Repatriation
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Foreign Currency Transaction Gain (Loss), Realized			14			14
8.50% senior notes due May 2019
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Extinguishment of debt, make-whole premium						230
Aflac Japan
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings		882	789		2,559	2,365
Aflac U.S.
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings		323	286		946	864
Other business segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings		4	5		12	10
Total Business Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings		1,209	1,080		3,517	3,239
Interest expense, noninsurance operations
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings		(31)	(30)		(90)	(117)
Corporate and eliminations
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pretax operating earnings		$ (31)	$ (23)		$ (91)	$ (64)

[1] Excluding a gain of $20 and $22 for the three-month periods and $64 and $62 for the nine-month periods ended September 30, 2016, and 2015, 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

[2] Includes a loss of $14 for the three- and nine-month periods ended September 30, 2015, related to the change in value of yen repatriation received in advance of settlement of certain foreign currency derivatives. This loss was offset by derivative gains included in realized investment gains (losses).

[3] Includes a cash outflow of $230 for the make-whole payment associated with the early extinguishment of debt