PENSION AND POSTRETIREMENT BENEFIT PLANS (Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 96	$ 63	$ 71
Total net periodic benefit cost/(credit)	(13)	1,599	(27)
Pension Plans, Defined Benefit [Member]
Pension, Postretirement And Postemployment Liabilities Statement [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	96	63
Service cost - benefits earned during the year	48	26	26
Interest cost on projected benefit obligation	42	115	193
Expected return on plan assets	(98)	(200)	(386)
Amortization of prior service costs	(4)	(4)	(4)
Amortization of net actuarial (gain)/loss	44	59	74
Curtailments	10	1,640	121
Total net periodic benefit cost/(credit)	$ 42	$ 1,636	$ 24