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, 2012	Dec. 31, 2011	Dec. 31, 2010
Deferred policy acquisition costs:
Capitalization	$ 1,700	$ 1,600	$ 1,300
Aflac U.S.
Deferred policy acquisition costs:
Balance, beginning of year	2,687	2,548
Capitalization	570	522
Amortization	(400)	(383)
Foreign currency translation and other	0	0
Balance, end of year	2,857	2,687
Aflac Japan
Deferred policy acquisition costs:
Balance, beginning of year	7,102	6,390
Capitalization	1,177	1,043
Amortization	(716)	(650)
Foreign currency translation and other	(762)	319
Balance, end of year	$ 6,801	$ 7,102