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PENSIONS AND OTHER POSTRETIREMENT BENEFITS - Fair Value of Plan Assets (Details) - USD ($) $ in Millions | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
--- | --- | --- | ---
Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | $ 4,282 | $ 4,338 | $ 5,606
OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 739 | 728 | 812
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 1,920 | 1,553 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 441 | 324 |
Significant Other Observable Inputs (Level 2) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 657 | 678 |
Significant Other Observable Inputs (Level 2) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 121 | 196 |
Significant Unobservable Inputs (Level 3) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 770 | 912 | $ 904
Significant Unobservable Inputs (Level 3) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 27 | 35 |
Investments Measured at Net Asset Value | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 935 | 1,195 |
Investments Measured at Net Asset Value | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 150 | 173 |
U.S. equities | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 809 | 1,133 |
U.S. equities | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 102 | 113 |
U.S. equities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 809 | 564 |
U.S. equities | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 102 | 24 |
U.S. equities | Significant Other Observable Inputs (Level 2) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
U.S. equities | Significant Other Observable Inputs (Level 2) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
U.S. equities | Significant Unobservable Inputs (Level 3) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
U.S. equities | Significant Unobservable Inputs (Level 3) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
U.S. equities | Investments Measured at Net Asset Value | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 569 |
U.S. equities | Investments Measured at Net Asset Value | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 89 |
Global equities | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 567 | 434 |
Global equities | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 33 | 47 |
Global equities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 502 | 328 |
Global equities | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 3 | 5 |
Global equities | Significant Other Observable Inputs (Level 2) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Global equities | Significant Other Observable Inputs (Level 2) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Global equities | Significant Unobservable Inputs (Level 3) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Global equities | Significant Unobservable Inputs (Level 3) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Global equities | Investments Measured at Net Asset Value | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 65 | 106 |
Global equities | Investments Measured at Net Asset Value | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 30 | 42 |
U.S. government securities | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 821 | 530 |
U.S. government securities | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 193 | 228 |
U.S. government securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 22 | 87 |
U.S. government securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 119 | 149 |
U.S. government securities | Significant Other Observable Inputs (Level 2) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 657 | 380 |
U.S. government securities | Significant Other Observable Inputs (Level 2) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 27 | 79 |
U.S. government securities | Significant Unobservable Inputs (Level 3) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
U.S. government securities | Significant Unobservable Inputs (Level 3) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
U.S. government securities | Investments Measured at Net Asset Value | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 142 | 63 |
U.S. government securities | Investments Measured at Net Asset Value | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 47 | 0 |
U.S. corporate bonds | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 681 | 1,213 |
U.S. corporate bonds | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 357 | 263 |
U.S. corporate bonds | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 587 | 574 |
U.S. corporate bonds | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 214 | 146 |
U.S. corporate bonds | Significant Other Observable Inputs (Level 2) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 266 |
U.S. corporate bonds | Significant Other Observable Inputs (Level 2) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 94 | 117 |
U.S. corporate bonds | Significant Unobservable Inputs (Level 3) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
U.S. corporate bonds | Significant Unobservable Inputs (Level 3) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
U.S. corporate bonds | Investments Measured at Net Asset Value | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 94 | 373 |
U.S. corporate bonds | Investments Measured at Net Asset Value | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 49 | 0 |
Non U.S. and other bonds | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 160 | 32 |
Non U.S. and other bonds | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Non U.S. and other bonds | Significant Other Observable Inputs (Level 2) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 32 |
Non U.S. and other bonds | Significant Unobservable Inputs (Level 3) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Non U.S. and other bonds | Investments Measured at Net Asset Value | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 160 | 0 |
Hedge funds | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 403 | 115 |
Hedge funds | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 10 | 14 |
Hedge funds | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Hedge funds | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Hedge funds | Significant Other Observable Inputs (Level 2) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Hedge funds | Significant Other Observable Inputs (Level 2) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Hedge funds | Significant Unobservable Inputs (Level 3) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 118 | 115 |
Hedge funds | Significant Unobservable Inputs (Level 3) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 10 | 14 |
Hedge funds | Investments Measured at Net Asset Value | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 285 | 0 |
Hedge funds | Investments Measured at Net Asset Value | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Private equity | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 146 | 143 |
Private equity | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Private equity | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Private equity | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Private equity | Significant Other Observable Inputs (Level 2) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Private equity | Significant Other Observable Inputs (Level 2) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Private equity | Significant Unobservable Inputs (Level 3) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 146 | 143 |
Private equity | Significant Unobservable Inputs (Level 3) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Private equity | Investments Measured at Net Asset Value | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Private equity | Investments Measured at Net Asset Value | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Structured credit | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 220 | 298 |
Structured credit | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 7 | 9 |
Structured credit | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Structured credit | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Structured credit | Significant Other Observable Inputs (Level 2) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Structured credit | Significant Other Observable Inputs (Level 2) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Structured credit | Significant Unobservable Inputs (Level 3) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 220 | 298 |
Structured credit | Significant Unobservable Inputs (Level 3) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 7 | 9 |
Structured credit | Investments Measured at Net Asset Value | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Structured credit | Investments Measured at Net Asset Value | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Real estate | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 475 | 356 |
Real estate | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 34 | 12 |
Real estate | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Real estate | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Real estate | Significant Other Observable Inputs (Level 2) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Real estate | Significant Other Observable Inputs (Level 2) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Real estate | Significant Unobservable Inputs (Level 3) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 286 | 356 |
Real estate | Significant Unobservable Inputs (Level 3) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 10 | 12 |
Real estate | Investments Measured at Net Asset Value | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 189 | 0 |
Real estate | Investments Measured at Net Asset Value | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 24 | 0 |
Absolute return fixed income | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 84 |
Absolute return fixed income | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 42 |
Absolute return fixed income | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Absolute return fixed income | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Absolute return fixed income | Significant Other Observable Inputs (Level 2) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Absolute return fixed income | Significant Other Observable Inputs (Level 2) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Absolute return fixed income | Significant Unobservable Inputs (Level 3) | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Absolute return fixed income | Significant Unobservable Inputs (Level 3) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Absolute return fixed income | Investments Measured at Net Asset Value | Pension Benefits |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 84 |
Absolute return fixed income | Investments Measured at Net Asset Value | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 42 |
Debt Security, Corporate, Non-US | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 3 | 0 |
Debt Security, Corporate, Non-US | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 3 | 0 |
Debt Security, Corporate, Non-US | Significant Other Observable Inputs (Level 2) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Debt Security, Corporate, Non-US | Significant Unobservable Inputs (Level 3) | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | 0 | 0 |
Debt Security, Corporate, Non-US | Investments Measured at Net Asset Value | OPEB |  |  |
Defined Benefit Plan, Information about Plan Assets [Abstract] |  |  |
Fair value of pension assets by asset category | $ 0 | $ 0 |

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