INCOME TAXES - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended																12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010		Apr. 02, 2012	Dec. 31, 2012 Expiring in 2030	Dec. 31, 2012 Expiring in 2031	Dec. 31, 2012 Expiring in 2032	Dec. 31, 2012 Expiring in 2013	Dec. 31, 2012 Expiring in 2014	Dec. 31, 2012 Expiring in 2015	Dec. 31, 2012 Expiring In 2016	Dec. 31, 2012 Expired In 2012	Apr. 01, 2015 Change in Income Tax Rate	Dec. 31, 2012 Aflac Japan	Dec. 31, 2011 Aflac Japan	Dec. 31, 2010 Aflac Japan	Dec. 31, 2012 Aflac Japan Dollar denominated investment portfolio	Dec. 31, 2011 Aflac Japan Dollar denominated investment portfolio	Dec. 31, 2010 Aflac Japan Dollar denominated investment portfolio	Dec. 31, 2012 Aflac Japan Foreign tax credits	Dec. 31, 2011 Aflac Japan Foreign tax credits	Dec. 31, 2012 Aflac U.S.	Dec. 31, 2011 Aflac U.S.	Dec. 31, 2010 Aflac U.S.	Dec. 31, 2012 Aflac U.S. Foreign tax credits	Dec. 31, 2011 Aflac U.S. Foreign tax credits
Income Taxes [Line Items]
Japan tax rate							33.30%									30.80%
Deferred tax expense (benefit)	$ 620		$ 122		$ 371												$ 950	$ (301)	$ 538				$ 374	$ (744)	$ (330)	$ 423	$ (167)	$ (374)	$ 744
The expected U.S. tax rate	35.00%
Income tax expense (benefit) related to items of other comprehensive income (loss)	1,078		392		(32)															492	(152)	(322)
Effective income tax rate excluding income tax expense (benefit) related to Aflac Japan's dollar-denominated portfolio																				32.00%	34.00%	32.00%
Non-life operating loss carryforwards, limitations	only 35% of non-life operating losses can be offset against life insurance taxable income each year
Non-life operating loss carryforwards								22	38	83
Tax Credit Carryforward, Amount	0
Capital loss carryforwards available to offset capital gains	2,045										3	181	550	1,311	0
Unrecognized tax benefits, tax positions for which the ultimate deductibility is highly certain	21	[1]	31	[1]	24	[1]
Unrecognized tax benefits, permanent uncertainties	2
Unrecognized tax benefits, interest and penalties expense	7		5		3
Unrecognized tax benefits, accrued interest and penalties	$ 12		$ 19

[1] Amounts do not include tax deductions of $7 at December 31, 2012, $10 at December 31, 2011, and $8 at January 1, 2011.