STATUTORY ACCOUNTING AND DIVIDEND RESTRICTIONS - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statutory Accounting Practices [Line Items]
Statutory accounting practices, statutory capital and surplus required	$ 500
Aflac
Statutory Accounting Practices [Line Items]
Net Income, Nebraska state basis	1,300	$ 2,600	$ 2,800
Capital and surplus, statutory accounting practices of the state or country basis	2,600	11,001
Amount available for dividend distribution without prior approval from regulatory agency	1,300
Dividends declared	12,300
Non-cash extraordinary dividends	11,000
Aflac Japan
Statutory Accounting Practices [Line Items]
Capital and surplus, statutory accounting practices of the state or country basis	$ 6,400	$ 6,700