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, 2014	Dec. 31, 2013
Statutory Accounting Practices [Line Items]
Capital and surplus, Nebraska state basis	$ 10,839	$ 9,630
Capital and surplus, NAIC basis	10,803	9,624
Refundable lease deposits - Japan
Statutory Accounting Practices [Line Items]
State permitted practice amount	(36)	(41)
Separate Account Funding Agreements
Statutory Accounting Practices [Line Items]
State permitted practice amount	$ 0	$ 35