STATUTORY ACCOUNTING AND DIVIDEND RESTRICTIONS - Reconciliation of Capital and Surplus Between Sap and Practices Permitted by the State of Nebraska (Detail) (Aflac, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Statutory Accounting Practices [Line Items]
Capital and surplus, Nebraska state basis	$ 8,892	$ 6,371
Capital and surplus, NAIC basis	8,889	6,363
Refundable lease deposits - Japan
Statutory Accounting Practices [Line Items]
State permitted practice amount	(49)	(53)
Separate Account Funding Agreements
Statutory Accounting Practices [Line Items]
State permitted practice amount	$ 46	$ 45