DEFERRED POLICY ACQUISITION COSTS AND INSURANCE EXPENSES - Advertising Expense (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Advertising Costs [Line Items]
Advertising expense	$ 254	$ 258	$ 228
Aflac Japan
Advertising Costs [Line Items]
Advertising expense	127	128	112
Aflac U.S.
Advertising Costs [Line Items]
Advertising expense	$ 127	$ 130	$ 116