POLICY LIABILITIES - Liability for Future Policy Benefits (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	65,646	69,136
Percentage of advanced premiums to unearned premiums	80.00%	82.00%
Aflac U.S.
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	5.70%	5.80%	6.00%
Aflac U.S. | Health insurance | 2012 - 2014
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	588	345
Aflac U.S. | Health insurance | 2011
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	4.75%
Interest Rates In 20 Years	4.75%
Liability amounts	276	243
Aflac U.S. | Health insurance | 2005-2010
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	5.50%
Interest Rates In 20 Years	5.50%
Liability amounts	2,951	2,897
Aflac U.S. | Health insurance | 1988-2004
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	8.00%
Interest Rates In 20 Years	6.00%
Liability amounts	706	725
Aflac U.S. | Health insurance | 1986-2004
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	6.00%
Interest Rates In 20 Years	6.00%
Liability amounts	1,293	1,301
Aflac U.S. | Health insurance | 1981-1986
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	183	190
Aflac U.S. | Health insurance | 1998-2004
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	7.00%
Interest Rates In 20 Years	7.00%
Liability amounts	1,260	1,237
Aflac U.S. | Health insurance | Other years
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	21	22
Aflac U.S. | Life insurance | 1956-2014
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	452	396
Aflac Japan
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	3.80%	3.90%	4.00%
Aflac Japan | Health insurance | 2002-2014
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	3,900	3,370
Aflac Japan | Health insurance | 1974-2013
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	3,449	3,889
Aflac Japan | Health insurance | 1998-2014
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	3.00%
Interest Rates In 20 Years	3.00%
Liability amounts	10,641	11,763
Aflac Japan | Health insurance | 1997-1999
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	3.50%
Interest Rates In 20 Years	3.50%
Liability amounts	2,461	2,842
Aflac Japan | Health insurance | 1994-1996
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	3,023	3,483
Aflac Japan | Health insurance | 1987 - 1994
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	5.50%
Interest Rates In 20 Years	5.50%
Liability amounts	14,394	16,727
Aflac Japan | Health insurance | 1985-1991
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	1,923	2,262
Aflac Japan | Health insurance | 1978-1984
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	6.50%
Interest Rates In 20 Years	5.50%
Liability amounts	2,260	2,699
Aflac Japan | Life insurance | 2013 - 2014
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	312	59
Aflac Japan | Life insurance | 2001-2013
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	3,674	3,009
Aflac Japan | Life insurance | 2011-2014
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	2.00%
Interest Rates In 20 Years	2.00%
Liability amounts	2,298	1,584
Aflac Japan | Life insurance | 2009-2011
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	2.25%
Interest Rates In 20 Years	2.25%
Liability amounts	1,890	1,648
Aflac Japan | Life insurance | 2005-2011
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	2.50%
Interest Rates In 20 Years	2.50%
Liability amounts	1,214	1,211
Aflac Japan | Life insurance | 1985-2006
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	2.70%
Interest Rates In 20 Years	2.25%
Liability amounts	2,006	2,303
Aflac Japan | Life insurance | 2007-2011
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	2.75%
Interest Rates In 20 Years	2.75%
Liability amounts	1,010	1,025
Aflac Japan | Life insurance | 1999-2011
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	3.00%
Interest Rates In 20 Years	3.00%
Liability amounts	1,944	2,164
Aflac Japan | Life insurance | 1996-2009
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	3.50%
Interest Rates In 20 Years	3.50%
Liability amounts	633	721
Aflac Japan | Life insurance | 1994-1996
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	884	1,021
Health insurance | Aflac U.S. | 2012 - 2014 | Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	3.00%
Interest Rates In 20 Years	3.00%
Health insurance | Aflac U.S. | 2012 - 2014 | Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	3.75%
Interest Rates In 20 Years	3.75%
Health insurance | Aflac U.S. | 1981-1986 | Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	6.50%
Interest Rates In 20 Years	5.50%
Health insurance | Aflac U.S. | 1981-1986 | Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	7.00%
Interest Rates In 20 Years	6.50%
Health insurance | Aflac Japan | 2002-2014 | Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	1.25%
Interest Rates In 20 Years	1.25%
Health insurance | Aflac Japan | 2002-2014 | Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	2.50%
Interest Rates In 20 Years	2.50%
Health insurance | Aflac Japan | 1974-2013 | Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	2.70%
Interest Rates In 20 Years	2.25%
Health insurance | Aflac Japan | 1974-2013 | Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	2.75%
Interest Rates In 20 Years	2.75%
Health insurance | Aflac Japan | 1994-1996 | Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	4.00%
Interest Rates In 20 Years	4.00%
Health insurance | Aflac Japan | 1994-1996 | Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	4.50%
Interest Rates In 20 Years	4.50%
Health insurance | Aflac Japan | 1985-1991 | Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	5.25%
Interest Rates In 20 Years	5.25%
Health insurance | Aflac Japan | 1985-1991 | Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	6.75%
Interest Rates In 20 Years	5.50%
Life insurance | Aflac U.S. | 1956-2014 | Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	3.50%
Interest Rates In 20 Years	3.50%
Life insurance | Aflac U.S. | 1956-2014 | Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	6.00%
Interest Rates In 20 Years	6.00%
Life insurance | Aflac Japan | 2013 - 2014 | Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	1.50%
Interest Rates In 20 Years	1.50%
Life insurance | Aflac Japan | 2013 - 2014 | Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	1.75%
Interest Rates In 20 Years	1.75%
Life insurance | Aflac Japan | 2001-2013 | Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	1.65%
Interest Rates In 20 Years	1.65%
Life insurance | Aflac Japan | 2001-2013 | Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	1.85%
Interest Rates In 20 Years	1.85%
Life insurance | Aflac Japan | 1994-1996 | Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	4.00%
Interest Rates In 20 Years	4.00%
Life insurance | Aflac Japan | 1994-1996 | Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	4.50%
Interest Rates In 20 Years	4.50%