Information on Transfers of Funds from Aflac Japan (Detail) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 USD ($)	Dec. 31, 2011 JPY (¥)	Dec. 31, 2010 USD ($)	Dec. 31, 2010 JPY (¥)	Dec. 31, 2009 USD ($)	Dec. 31, 2009 JPY (¥)
Segment Reporting Information [Line Items]
Management fees	$ 28		$ 30		$ 26
Allocated expenses	43		37		37
Profit repatriation	143	11,000	317	28,700	230	20,000
Total transfers from Aflac Japan	$ 214		$ 384		$ 293