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REINSURANCE Effect of Reinsurance on Premiums and Benefits and Claims (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Effects of Reinsurance [Line Items]
Direct premiums earned									$ 19,412us-gaap_DirectPremiumsEarned	$ 20,233us-gaap_DirectPremiumsEarned	$ 22,167us-gaap_DirectPremiumsEarned
Ceded premiums									(350)us-gaap_CededPremiumsEarned	(110)us-gaap_CededPremiumsEarned	(33)us-gaap_CededPremiumsEarned
Assumed premiums from other companies									10us-gaap_AssumedPremiumsEarned	12us-gaap_AssumedPremiumsEarned	14us-gaap_AssumedPremiumsEarned
Net premium income	4,489us-gaap_PremiumsEarnedNet	4,841us-gaap_PremiumsEarnedNet	4,888us-gaap_PremiumsEarnedNet	4,854us-gaap_PremiumsEarnedNet	4,910us-gaap_PremiumsEarnedNet	5,028us-gaap_PremiumsEarnedNet	5,013us-gaap_PremiumsEarnedNet	5,184us-gaap_PremiumsEarnedNet	19,072us-gaap_PremiumsEarnedNet	20,135us-gaap_PremiumsEarnedNet	22,148us-gaap_PremiumsEarnedNet
Direct benefits and claims									13,235	13,903
Assumed benefits and claims from other companies									5	8
Benefits and claims, net									12,937	13,813	15,330
All other
Effects of Reinsurance [Line Items]
Ceded premiums									(39)	(34)
Ceded benefits and claims									(27)	(31)
Aflac Japan
Effects of Reinsurance [Line Items]
Net premium income									13,861	14,982	17,151
Benefits and claims, net									10,084	10,924	12,496
Aflac Japan \| Closed medical block
Effects of Reinsurance [Line Items]
Ceded premiums									(311)	(76)
Ceded benefits and claims									$ (276)	$ (67)