BUSINESS SEGMENT AND FOREIGN INFORMATION - Information on Transfers of Funds from Aflac Japan (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting [Abstract]
Management fees	$ 93	$ 79	$ 53
Allocated expenses	109	106	101
Profit repatriation	1,150	1,286	2,139
Total transfers from Aflac Japan	$ 1,352	$ 1,471	$ 2,293