STATUTORY ACCOUNTING AND DIVIDEND RESTRICTIONS - Additional Information (Detail)			12 Months Ended							1 Months Ended	12 Months Ended
	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2014 Aflac USD ($)	Dec. 31, 2013 Aflac USD ($)	Dec. 31, 2012 Aflac USD ($)	Dec. 31, 2014 Aflac Separate Account Funding Agreements USD ($)	Dec. 31, 2013 Aflac Separate Account Funding Agreements USD ($)	Dec. 31, 2014 Aflac Japan USD ($)	Dec. 31, 2013 Aflac Japan USD ($)	Jul. 31, 2013 2014 profit repatriation USD ($)	Dec. 31, 2014 2014 profit repatriation USD ($)	Dec. 31, 2014 Foreign currency forwards December 2014 profit repatriation JPY (¥)	Dec. 31, 2014 Foreign currency forwards Profit repatriation JPY (¥)	Dec. 31, 2014 Foreign currency forwards and options July 2014 profit repatriation JPY (¥)	Dec. 31, 2014 Foreign currency forwards and options December 2014 profit repatriation JPY (¥)
Statutory Accounting Practices [Line Items]
Capital and surplus, statutory accounting practices of the state or country basis			$ 10,839,000,000	$ 9,630,000,000				$ 5,600,000,000	$ 4,200,000,000
Guaranteed separate account funding agreements, unrealized gain (loss)						0	35,000,000
Statutory Accounting Practices, Statutory Capital and Surplus Required	1,200,000,000
Net Income, Nebraska state basis			2,400,000,000	2,400,000,000	2,300,000,000
Amount available for dividend distribution without prior approval from regulatory agency			2,400,000,000
Dividends declared			1,500,000,000
Net Derivatives Notional Amount	23,662,000,000	22,475,000,000										50,000,000,000	157,500,000,000	52,500,000,000	50,000,000,000
Foreign Currency Transaction Gain (Loss), before Tax										$ 7,000,000	$ 45,000,000