PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS (Accumulated and Projected Benefit Obligations in Excess of Plan Assets) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation	$ 4,200	$ 4,071
Defied Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Fair Value of Plan Assets	3,095	3,148
Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation	4,229	4,097
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	4,200	4,100
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Plan Assets	$ 3,095	$ 3,148