DEFERRED POLICY ACQUISITION COSTS AND INSURANCE EXPENSES - Rollforward of Deferred Policy Acquisition Costs by Segment (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Deferred policy acquisition costs:
Balance, beginning of year	$ 8,798
Capitalization	1,300	1,400	1,700
Balance, end of year	8,273	8,798
Aflac U.S.
Deferred policy acquisition costs:
Balance, beginning of year	2,979	2,857
Capitalization	548	555
Amortization	(459)	(433)
Foreign currency translation and other	(6)	0
Balance, end of year	3,062	2,979
Aflac Japan
Deferred policy acquisition costs:
Balance, beginning of year	5,819	6,801
Capitalization	790	893
Amortization	(649)	(641)
Foreign currency translation and other	(749)	(1,234)
Balance, end of year	$ 5,211	$ 5,819