BUSINESS SEGMENT AND FOREIGN INFORMATION - Information on Transfers of Funds from Aflac Japan (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting [Abstract]
Management fees	$ 136	$ 93	$ 79
Allocated expenses	24	109	106
Profit remittances	808	1,150	1,286
Total transfers from Aflac Japan	$ 968	$ 1,352	$ 1,471