BUSINESS SEGMENT INFORMATION - Operations by Segment - Revenues (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 segment	Sep. 30, 2012
Segment Reporting, Revenue Reconciling Item [Line Items]
Number of Reportable Insurance Business Segments			2
Earned premiums	$ 5,028	$ 5,660	$ 15,225	$ 16,505
Net investment income	821	869	2,467	2,597
Other income	15	32	67	64
Realized investment gains (losses)	22	286	379	(177)
Total revenues	5,886	6,847	18,138	18,989
Aflac Japan
Segment Reporting, Revenue Reconciling Item [Line Items]
Earned premiums	3,735	4,405	11,357	12,769
Net investment income	659	713	1,986	2,134
Other income	8	22	46	38
Total revenues	4,402	5,140	13,389	14,941
Aflac U.S.
Segment Reporting, Revenue Reconciling Item [Line Items]
Earned premiums	1,293	1,254	3,868	3,736
Net investment income	159	153	473	457
Other income	1	5	4	10
Total revenues	1,453	1,412	4,345	4,203
Other business segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	11	10	38	40
Total Business Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	5,866	6,562	17,772	19,184
Corporate
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	71	65	229	197
Intercompany eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	$ (73)	$ (66)	$ (242)	$ (215)