STATUTORY ACCOUNTING AND DIVIDEND RESTRICTIONS - Profits Repatriated by Aflac Japan to Aflac U.S. (Detail) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 USD ($)	Dec. 31, 2012 JPY (¥)	Dec. 31, 2011 USD ($)	Dec. 31, 2011 JPY (¥)	Dec. 31, 2010 USD ($)	Dec. 31, 2010 JPY (¥)
Statutory Accounting Practices Disclosure [Abstract]
Profit repatriation	$ 422	¥ 33,100	$ 143	¥ 11,000	$ 317	¥ 28,700