REINSURANCE - Effect of Reinsurance on Premiums and Benefits and Claims (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Effects of Reinsurance [Line Items]
Direct premium income	$ 5,119	$ 4,464	$ 14,724	$ 13,426
Net premium income	5,022	4,380	14,447	13,176
Direct benefits and claims	3,463	3,000	9,898	9,037
Benefits and claims, net	3,378	2,927	9,657	8,816
All other
Effects of Reinsurance [Line Items]
Ceded premiums	(13)	(10)	(37)	(28)
Assumed premiums earned	2	2	6	6
Ceded benefits and claims	(10)	(6)	(26)	(20)
Assumed benefits and claims from other companies	1	2	2	3
Aflac Japan
Effects of Reinsurance [Line Items]
Net premium income	3,596	2,980	10,177	9,036
Aflac Japan \| Closed Block
Effects of Reinsurance [Line Items]
Ceded premiums	(148)	(130)	(423)	(352)
Assumed premiums earned	62	54	177	124
Ceded benefits and claims	(135)	(119)	(385)	(320)
Assumed benefits and claims from other companies	59	50	168	116
Intercompany eliminations
Effects of Reinsurance [Line Items]
Ceded benefits and claims	16	14	44	32
Assumed benefits and claims from other companies	$ (16)	$ (14)	$ (44)	$ (32)

Amount of earned premiums assumed from other entities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Amount, before premiums ceded to other entities and premiums assumed by the entity, of premiums earned.

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Amount, before effect of policies assumed or ceded, of expense related to provision for policy benefits and costs incurred.

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Amount of reduction of provision for policy benefits and costs incurred for policies ceded.

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