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DERIVATIVE INSTRUMENTS - Schedule of Notional Amounts of Outstanding Derivatives (Details) - Designated as Hedging Instrument [Member] lb in Millions, gal in Millions, MWh in Millions, MMBTU in Millions, $ in Millions | 6 Months Ended | 12 Months Ended
--- | --- | ---
Jun. 30, 2020 CAD ($) gal lb MMBTU MWh | Dec. 31, 2019 CAD ($) gal lb MMBTU MWh
Natural Gas [Member] |  |
Derivative [Line Items] |  |
Derivative, Nonmonetary Notional Amount | MMBTU | 39.2 | 20.1
Diesel [Member] |  |
Derivative [Line Items] |  |
Derivative, Nonmonetary Notional Amount | gal | 0.0 | 0.8
Zinc [Member] |  |
Derivative [Line Items] |  |
Derivative, Nonmonetary Notional Amount | lb | 18.2 | 0.0
Electricity [Member] |  |
Derivative [Line Items] |  |
Derivative, Nonmonetary Notional Amount, Energy Measure | MWh | 1.5 | 0.0
Canada, Dollars | Foreign Exchange Contract [Member] |  |
Derivative [Line Items] |  |
Derivative, Notional Amount | $ | $ 48.7 | $ 0.0

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