REINSURANCE - Effect of Reinsurance on Premiums and Benefits and Claims (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Effects of Reinsurance [Line Items]
Direct premium income	$ 4,933
Assumed premiums from other companies	3
Net premium income	4,854	5,184
Direct benefits and claims	3,289
Assumed benefits and claims from other companies	2
Benefits and claims, net	3,220	3,521
All Other
Effects of Reinsurance [Line Items]
Ceded premiums	(9)
Ceded benefits and claims	(7)
Aflac Japan
Effects of Reinsurance [Line Items]
Net premium income	3,560	3,905
Aflac Japan | Closed medical block
Effects of Reinsurance [Line Items]
Ceded premiums	(73)
Ceded benefits and claims	$ (64)