BUSINESS SEGMENT INFORMATION - Operations by Segment - Revenues (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014 segment		Sep. 30, 2013
Segment Reporting, Revenue Reconciling Item [Line Items]
Number of Reportable Insurance Business Segments				2
Net earned premiums	$ 4,841		$ 5,028	$ 14,583		$ 15,225
Net investment income	841		821	2,511		2,467
Other income	38		15	48		67
Total revenues	5,736		5,886	17,214		18,138
Other non-operating income (loss)	27		0	7		0
Realized investment gains (losses), non-operating	6	[1]	22	42	[1]	379
Gain (loss) on change in fair value of derivative, interest rate component, operating	10			30
Aflac Japan
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums	3,534		3,735	10,672		11,357
Net investment income	676		659	2,019		1,986
Other income	9		8	25		46
Total revenues	4,219		4,402	12,716		13,389
Aflac U.S.
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums	1,306		1,293	3,910		3,868
Net investment income	162		159	484		473
Other income	0		1	2		4
Total revenues	1,468		1,453	4,396		4,345
Other business segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	11		11	29		38
Total Business Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	5,698		5,866	17,141		17,772
Corporate
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	43		71	194		229
Intercompany eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	$ (38)		$ (73)	$ (170)		$ (242)

[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