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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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- Definition

Inflation rate

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- Definition

Risk Free Rate

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- Definition

[Line Items] for Schedule of Asset Retirement Obligations [Table]

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- Definition

Undiscounted Decommissioning Liability

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