INCOME TAXES (Reserve for unrecognized tax benefits, interest and penalties) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Balance at beginning of year	$ 376	$ 404
Additions:
Prior year tax positions	48	73	$ 100
Current year tax positions	10	11	14
Decreases:
Prior year tax positions	(60)	(75)	(86)
Settlements with taxing authorities	(79)	(37)	(9)
Lapse of statute of limitations	0	0	(5)
Balance at end of year	$ 295	$ 376	$ 390