POLICY LIABILITIES - Liability for Future Policy Benefits (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	76,463	79,278
Aflac U.S.
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	6.00%	6.00%	6.00%
Aflac U.S. | Health insurance | 2012
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	3.75%
Interest Rates In 20 Years	3.75%
Liability amounts	127	0
Aflac U.S. | Health insurance | 2005-2011
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	2,977	2,713
Aflac U.S. | Health insurance | 2005-2011 | Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	4.75%
Interest Rates In 20 Years	4.75%
Aflac U.S. | Health insurance | 2005-2011 | Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	5.50%
Interest Rates In 20 Years	5.50%
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	1,200	1,148
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	748	777
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	1,317	1,328
Aflac U.S. | Health insurance | 1985-1986
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	6.50%
Interest Rates In 20 Years	6.50%
Liability amounts	23	23
Aflac U.S. | Health insurance | 1981-1986
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	7.00%
Interest Rates In 20 Years	5.50%
Liability amounts	175	181
Aflac U.S. | Health insurance | Other year
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	23	24
Aflac U.S. | Life insurance | 1956-2012
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	343	291
Aflac U.S. | Life insurance | 1956-2012 | 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%
Aflac U.S. | Life insurance | 1956-2012 | 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%
Aflac Japan
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	4.00%	4.00%	4.40%
Aflac Japan | Health insurance | 1974-2012
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	7,142	2,441
Aflac Japan | Health insurance | 1974-2012 | 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%
Aflac Japan | Health insurance | 1974-2012 | 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%
Aflac Japan | Health insurance | 1998-2012
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	13,685	18,777
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	3,482	3,885
Aflac Japan | Health insurance | 1994-1996
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	4,261	4,749
Aflac Japan | Health insurance | 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%
Aflac Japan | Health insurance | 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%
Aflac Japan | Health insurance | 1987-1994
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	21,866	24,607
Aflac Japan | Health insurance | 1987-1994 | 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%
Aflac Japan | Health insurance | 1987-1994 | Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	5.50%
Interest Rates In 20 Years	5.50%
Aflac Japan | Health insurance | 1978-1986
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates In 20 Years	5.50%
Liability amounts	5,009	5,761
Aflac Japan | Health insurance | 1978-1986 | Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	6.50%
Aflac Japan | Health insurance | 1978-1986 | Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	6.75%
Aflac Japan | Life insurance | 1994-1996
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	1,250	1,395
Aflac Japan | Life insurance | 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%
Aflac Japan | Life insurance | 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%
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	1,231	1,079
Aflac Japan | Life insurance | 2001-2012
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	2,238	1,501
Aflac Japan | Life insurance | 2001-2012 | 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%
Aflac Japan | Life insurance | 2001-2012 | 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%
Aflac Japan | Life insurance | 2011-2012
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	733	122
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	1,374	823
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	2,791	0
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	1,049	896
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	2,547	5,795
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	872	962