Summary of Significant Accounting Policies - Additional Information (Detail) (Aflac Japan)	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Aflac Japan
Significant Accounting Policies [Line Items]
Aflac Japan's percentage of the Company's total revenues	75.00%	75.00%
Percentage of the Company Assets	85.00%		85.00%