DEFERRED POLICY ACQUISITION COSTS AND INSURANCE EXPENSES - Advertising Expense (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Advertising Costs [Line Items]
Advertising expense	$ 211	$ 229	$ 240
Aflac Japan
Advertising Costs [Line Items]
Advertising expense	82	103	112
Aflac U.S.
Advertising Costs [Line Items]
Advertising expense	$ 129	$ 126	$ 128