DEFERRED POLICY ACQUISITION COSTS AND INSURANCE EXPENSES - Rollforward of Deferred Policy Acquisition Costs by Segment (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred policy acquisition costs:
Balance, beginning of year	$ 8,511
Capitalization	1,400	$ 1,300	$ 1,300
Amortization	(1,141)	(1,066)	(1,108)
Balance, end of year	8,993	8,511
Aflac Japan
Deferred policy acquisition costs:
Balance, beginning of year	5,370	5,211
Capitalization	864	738
Amortization	(644)	(578)	(649)
Foreign currency translation and other	175	(1)
Balance, end of year	5,765	5,370	5,211
Aflac U.S.
Deferred policy acquisition costs:
Balance, beginning of year	3,141	3,062
Capitalization	583	578
Amortization	(497)	(488)	(459)
Foreign currency translation and other	1	(11)
Balance, end of year	$ 3,228	$ 3,141	$ 3,062