Liability for Future Policy (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	$ 79,278	$ 72,103
Health insurance | Aflac Japan | 2005 - 2011
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	2,441	1,577
Health insurance | Aflac Japan | 2005 - 2011 | 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%
Health insurance | Aflac Japan | 2005 - 2011 | 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 | 1974 - 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	18,777	13,034
Health insurance | Aflac Japan | 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	3,885	3,942
Health insurance | Aflac Japan | 1994-1996
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	4,749	6,083
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 | 1987-1994
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	24,607	24,420
Health insurance | Aflac Japan | 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%
Health insurance | Aflac Japan | 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%
Health insurance | Aflac Japan | 1978-1986
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates In 20 Years	5.50%
Liability amounts	5,761	5,634
Health insurance | Aflac Japan | 1978-1986 | Lower Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	6.50%
Health insurance | Aflac Japan | 1978-1986 | Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	6.75%
Health insurance | Aflac Japan | 1974-1979
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	7.00%
Interest Rates In 20 Years	5.00%
Liability amounts	0	993
Health insurance | Aflac U.S. | 2005 - 2011
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	2,713	2,293
Health insurance | Aflac U.S. | 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%
Health insurance | Aflac U.S. | 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%
Health insurance | Aflac U.S. | 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	1,148	1,123
Health insurance | Aflac U.S. | 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	777	845
Health insurance | Aflac U.S. | 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	1,328	1,337
Health insurance | Aflac U.S. | 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	24
Health insurance | Aflac U.S. | 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	181	188
Health insurance | Aflac U.S. | Other year
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	24	26
Life insurance | Aflac Japan | 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	1,079	753
Life insurance | Aflac Japan | 1994-1996
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	1,395	1,334
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%
Life insurance | Aflac Japan | 2011
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	122	0
Life insurance | Aflac Japan | 2009-2010
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	823	262
Life insurance | Aflac Japan | 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	896	503
Life insurance | Aflac Japan | 2001-2011
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	1,501	1,163
Life insurance | Aflac Japan | 2001-2011 | 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 | 2001-2011 | 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 | 1985-2011
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	5,795	2,543
Life insurance | Aflac Japan | 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	962	904
Life insurance | Aflac Japan | 1985-1993
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	0	2,877
Life insurance | Aflac Japan | 1985-1993 | 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%
Life insurance | Aflac Japan | 1985-1993 | Upper Limit
Liability for Future Policy Benefit, by Product Segment [Line Items]
Interest Rates Year of Issue	5.65%
Interest Rates In 20 Years	5.65%
Life insurance | Aflac U.S. | 1956-2011
Liability for Future Policy Benefit, by Product Segment [Line Items]
Liability amounts	$ 291	$ 245
Life insurance | Aflac U.S. | 1956-2011 | 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 U.S. | 1956-2011 | 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%