SHAREHOLDERS' EQUITY - Reconciliation of Number of Shares of Common Stock (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Common Stock Issued [Roll Forward]
Balance, beginning of period	1,349,309	1,347,540	1,345,762
Exercise of stock options and issuance of restricted shares	1,709	1,769	1,778
Balance, end of period	1,351,018	1,349,309	1,347,540
Treasury Stock [Roll Forward]
Balance, beginning of period	622,516	592,254	564,852
Exercise of stock options	(638)	(1,584)	(1,874)
Balance, end of period	658,564	622,516	592,254
Shares outstanding, end of period	692,454	726,793	755,286
Treasury Stock
Treasury Stock [Roll Forward]
Stock acquired under share repurchase program, shares	37,899	31,994	28,949
Other purchases	542	592	392
Shares issued to AFL Stock Plan	(2,021)	(1,610)	(1,306)
Exercise of stock options	(121)	(418)	(519)
Other dispositions	(251)	(296)	(114)