REINSURANCE - Effect of Reinsurance on Premiums and Benefits and Claims (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Effects of Reinsurance [Line Items]
Direct premium income	$ 4,969		$ 9,902
Assumed premiums from other companies	2		5
Net premium income	4,888	5,013	9,742	10,197
Direct benefits and claims	3,361		6,650
Assumed benefits and claims from other companies	3		5
Benefits and claims, net	3,293	3,411	6,513	6,932
All Other
Effects of Reinsurance [Line Items]
Ceded premiums	(11)		(20)
Ceded benefits and claims	(6)		(13)
Aflac Japan
Effects of Reinsurance [Line Items]
Net premium income	3,578	3,717	7,138	7,622
Aflac Japan | Closed medical block
Effects of Reinsurance [Line Items]
Ceded premiums	(72)		(145)
Ceded benefits and claims	$ (65)		$ (129)