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PENSION AND POST RETIREMENT BENEFITS (Components of Accumulated Other Comprehensive Loss (Income) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019
Pension Plan [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Other Comprehensive Income (Loss), Defined Benefit Plan, (Gain) Loss Arising During Period, before Tax | $ (219) | $ 50
Actual returns on assets (over) under estimate | (332) | (44)
Amortization of net actuarial loss | (27) | (24)
Amortization of prior service credit (cost) | (1) | (1)
Current year prior service cost | 6 | 0
Other | (27) | 7
Other Postretirement Benefits Plan [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Other Comprehensive Income (Loss), Defined Benefit Plan, (Gain) Loss Arising During Period, before Tax | (15) | (6)
Actual returns on assets (over) under estimate | (26) | (18)
Amortization of net actuarial loss | (3) | (5)
Amortization of prior service credit (cost) | 2 | 2
Current year prior service cost | 0 | 0
Other | (2) | (5)
Change in Assumptions for Defined Benefit Plans, Discount Rates [Member] | Pension Plan [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Other Comprehensive Income (Loss), Defined Benefit Plan, (Gain) Loss Arising During Period, before Tax | 181 | 106
Change in Assumptions for Defined Benefit Plans, Discount Rates [Member] | Other Postretirement Benefits Plan [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Other Comprehensive Income (Loss), Defined Benefit Plan, (Gain) Loss Arising During Period, before Tax | 44 | 26
Change in Assumptions for Defined Benefit Plans, Demographic [Member] | Pension Plan [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Other Comprehensive Income (Loss), Defined Benefit Plan, (Gain) Loss Arising During Period, before Tax | (3) | 12
Change in Assumptions for Defined Benefit Plans, Demographic [Member] | Other Postretirement Benefits Plan [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Other Comprehensive Income (Loss), Defined Benefit Plan, (Gain) Loss Arising During Period, before Tax | (11) | 4
Changes in Assumptions for Defined Benefit Plans, Mortality [Member] | Pension Plan [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Other Comprehensive Income (Loss), Defined Benefit Plan, (Gain) Loss Arising During Period, before Tax | (16) | (6)
Changes in Assumptions for Defined Benefit Plans, Mortality [Member] | Other Postretirement Benefits Plan [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Other Comprehensive Income (Loss), Defined Benefit Plan, (Gain) Loss Arising During Period, before Tax | (4) | (4)
Changes in Assumptions for Defined Benefit Plans, Per Capita Claims [Member] | Pension Plan [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Other Comprehensive Income (Loss), Defined Benefit Plan, (Gain) Loss Arising During Period, before Tax | 0 | 0
Changes in Assumptions for Defined Benefit Plans, Per Capita Claims [Member] | Other Postretirement Benefits Plan [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Other Comprehensive Income (Loss), Defined Benefit Plan, (Gain) Loss Arising During Period, before Tax | (10) | (9)
Changes in Assumptions for Defined Benefit Plans, Other Actuarial (Gain) Loss [Member] | Pension Plan [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Other Comprehensive Income (Loss), Defined Benefit Plan, (Gain) Loss Arising During Period, before Tax | 0 | 0
Changes in Assumptions for Defined Benefit Plans, Other Actuarial (Gain) Loss [Member] | Other Postretirement Benefits Plan [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Other Comprehensive Income (Loss), Defined Benefit Plan, (Gain) Loss Arising During Period, before Tax | (5) | 3
Changes in Assumptions for Defined Benefit Plans, Actuarial (Gain) Loss [Member] | Pension Plan [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Other Comprehensive Income (Loss), Defined Benefit Plan, (Gain) Loss Arising During Period, before Tax | 162 | 112
Changes in Assumptions for Defined Benefit Plans, Actuarial (Gain) Loss [Member] | Other Postretirement Benefits Plan [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Other Comprehensive Income (Loss), Defined Benefit Plan, (Gain) Loss Arising During Period, before Tax | $ 14 | $ 20

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