INCOME TAXES - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Apr. 02, 2012	Jan. 01, 2015
Income Taxes [Line Items]
Unrecognized tax benefit, deductibility highly certain, timing uncertain	$ 307	$ 327
Japan Tax Rate					33.30%
Deferred tax expense (benefit)	461	422	620
The expected U.S. tax rate	35.00%	35.00%
Income tax expense (benefit) related to items of other comprehensive income (loss)	1,803	(581)	1,078
Non-life operating loss carryforwards, limitations	only 35% of non-life operating losses can be offset against life insurance taxable income each year
Tax credit carryforward, amount	0
Unrecognized tax benefits, permanent uncertainties	2
Unrecognized tax benefits, interest and penalties expense	11	11	7
Unrecognized tax benefits, accrued interest and penalties	30	26
Capital loss carryforwards	73
Expiring in 2031
Income Taxes [Line Items]
Non-life operating loss carryforwards	18
Expiring in 2032
Income Taxes [Line Items]
Non-life operating loss carryforwards	17
Expiring in 2033
Income Taxes [Line Items]
Non-life operating loss carryforwards	2
Expiring in 2034
Income Taxes [Line Items]
Non-life operating loss carryforwards	1
Change In Income Tax Rate
Income Taxes [Line Items]
Japan Tax Rate						30.80%
Aflac Japan
Income Taxes [Line Items]
Deferred tax expense (benefit)	125	299	950
Aflac Japan | Dollar denominated investment portfolio
Income Taxes [Line Items]
Income tax expense (benefit) related to items of other comprehensive income (loss)		614	492
Effective income tax rate excluding income tax expense (benefit) related to Aflac Japan's dollar-denominated portfolio		31.00%	32.00%
Aflac Japan | Foreign Tax Credits
Income Taxes [Line Items]
Deferred tax expense (benefit)			374	(744)
Aflac U.S.
Income Taxes [Line Items]
Deferred tax expense (benefit)	336	123	(330)
Aflac U.S. | Foreign Tax Credits
Income Taxes [Line Items]
Deferred tax expense (benefit)			$ (374)	$ 744