DEFERRED POLICY ACQUISITION COSTS AND INSURANCE EXPENSES - Lease and Rental Expense (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Lease and Rental Expense [Line Items]
Lease and rental expense	$ 81	$ 82	$ 77
Aflac Japan
Lease and Rental Expense [Line Items]
Lease and rental expense	71	73	68
Aflac U.S.
Lease and Rental Expense [Line Items]
Lease and rental expense	9	8	8
All Other
Lease and Rental Expense [Line Items]
Lease and rental expense	$ 1	$ 1	$ 1