DEFERRED POLICY ACQUISITION COSTS AND INSURANCE EXPENSES - Rollforward of Deferred Policy Acquisition Costs by Segment (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Deferred policy acquisition costs:
Balance, beginning of year	$ 8,273
Capitalization	1,300	$ 1,300	$ 1,400
Amortization	(1,066)	(1,108)	(1,074)
Balance, end of year	8,511	8,273
Aflac U.S.
Deferred policy acquisition costs:
Balance, beginning of year	3,062	2,979
Capitalization	578	548
Amortization	(488)	(459)	(433)
Foreign currency translation and other	(11)	(6)
Balance, end of year	3,141	3,062	2,979
Aflac Japan
Deferred policy acquisition costs:
Balance, beginning of year	5,211	5,819
Capitalization	738	790
Amortization	(578)	(649)	(641)
Foreign currency translation and other	(1)	(749)
Balance, end of year	$ 5,370	$ 5,211	$ 5,819