REINSURANCE - Effect of Reinsurance on Premiums and Benefits and Claims (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Effects of Reinsurance [Line Items]
Direct premium income	$ 4,918		$ 14,820
Assumed premiums from other companies	3		8
Net premium income	4,841	5,028	14,583	15,225
Direct benefits and claims	3,425		10,075
Assumed benefits and claims from other companies	2		7
Benefits and claims, net	3,355	3,485	9,868	10,417
All Other
Effects of Reinsurance [Line Items]
Ceded premiums	(10)		(30)
Ceded benefits and claims	(9)		(22)
Aflac Japan
Effects of Reinsurance [Line Items]
Net premium income	3,534	3,735	10,672	11,357
Aflac Japan | Closed medical block
Effects of Reinsurance [Line Items]
Ceded premiums	(70)		(215)
Ceded benefits and claims	$ (63)		$ (192)