STATUTORY ACCOUNTING AND DIVIDEND RESTRICTIONS - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Aflac
Statutory Accounting Practices [Line Items]
Net Income, Nebraska state basis	$ 2,300,000,000	$ 444,000,000	$ 1,500,000,000
Capital and surplus, statutory accounting practices of the state or country basis	8,892,000,000	6,371,000,000
Amount available for dividend distribution without prior approval from regulatory agency	2,300,000,000
Dividends declared	0
Aflac | Separate Account Funding Agreements
Statutory Accounting Practices [Line Items]
Guaranteed separate account funding agreements, unrealized gain (loss)	46,000,000	45,000,000
Aflac Japan
Statutory Accounting Practices [Line Items]
Capital and surplus, statutory accounting practices of the state or country basis	$ 3,900,000,000	$ 2,700,000,000