INCOME TAXES - Components of Income Tax Expense (Benefit) Applicable to Pretax Earnings (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of Provision of Income Taxes [Line Items]
Current									$ 1,236	$ 816	$ 891
Deferred									422	620	122
Total income tax expense	353	367	469	469	299	463	258	417	1,658	1,436	1,013
Aflac U.S.
Reconciliation of Provision of Income Taxes [Line Items]
Current									302	303	533
Deferred									123	(330)	423
Total income tax expense									425	(27)	956
Aflac Japan
Reconciliation of Provision of Income Taxes [Line Items]
Current									934	513	358
Deferred									299	950	(301)
Total income tax expense									$ 1,233	$ 1,463	$ 57