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REVENUES - Deferred Revenue (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Deferred Revenue Arrangement [Line Items] |  |  |
Realization of Deferred Revenue | $ 35 | $ 0 | $ 0
Other Current Liabilities [Member] |  |  |
Deferred Revenue Arrangement [Line Items] |  |  |
Deferred Revenue (Current) | 7 | 22 | 21
Net Increase (Decrease) | (15) | 1 |
Other Noncurrent Liabilities [Member] |  |  |
Deferred Revenue Arrangement [Line Items] |  |  |
Net Increase (Decrease) | (26) | (13) |
Deferred Revenue (Long-Term) | $ 0 | $ 26 | $ 39

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