BUSINESS SEGMENT INFORMATION - Operations by Segment - Revenues (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015 segment		Mar. 31, 2014
Segment Reporting, Revenue Reconciling Item [Line Items]
Number of Reportable Insurance Business Segments	2
Net earned premiums	$ 4,432		$ 4,854
Net investment income	782		827
Other income	(1)		5
Total revenues	5,226		5,640
Other non-operating income (loss)	(18)		(9)
Realized investment gains (losses), non-operating	(4)	[1]	(56)	[1]
Gain (loss) on change in fair value of derivative, interest rate component, operating	17		10
Aflac Japan
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums	3,078		3,560
Net investment income	613		663
Other income	8		8
Total revenues	3,699		4,231
Aflac U.S.
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums	1,339		1,294
Net investment income	166		161
Other income	3		0
Total revenues	1,508		1,455
Other business segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	26		12
Total Business Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	5,233		5,698
Corporate
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	97		78
Intercompany eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	$ (82)		$ (71)

[1] Excluding a gain of $17 and $10 for the three-month periods ended March 31, 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