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ASSET RETIREMENT OBLIGATIONS AND RESTRICTED CASH - Narrative (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 | Dec. 31, 2018
Schedule of Asset Retirement Obligations [Line Items] |  |
Inflation rate | 2.00% |
Undiscounted decommissioning liability | $ 42 | $ 41
Minimum |  |
Schedule of Asset Retirement Obligations [Line Items] |  |
Risk Free Rate | 9.50% |
Maximum |  |
Schedule of Asset Retirement Obligations [Line Items] |  |
Risk Free Rate | 11.50% |

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