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Derivatives, Hedging Programs and Other Financial Instruments, Material Derivative Positions (Details) mmlbs in Millions | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Mar. 31, 2018 EUR (€) MMBTU MWH mmlbs
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Alloy Metal Hedge | Designated as Hedging Instrument | Purchase |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative, Nonmonetary Notional Amount |  |  |  |  | 6.1
Natural Gas Member | Designated as Hedging Instrument | Purchase |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative, Nonmonetary Notional Amount | MMBTU |  |  |  |  | 3,520,000
Natural Gas Member | Scenario, Forecast |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage |  | 69.00% | 70.00% | 72.00% |
Aluminum Member | Designated as Hedging Instrument | Purchase |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative, Nonmonetary Notional Amount |  |  |  |  | 141.0
Aluminum Member | Designated as Hedging Instrument | Sales |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative, Nonmonetary Notional Amount |  |  |  |  | 3.9
Electricity Member | Designated as Hedging Instrument | Purchase |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative, Nonmonetary Notional Amount | MWH |  |  |  |  | 175,680
Electricity Member | Scenario, Forecast |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage |  | 53.00% | 53.00% | 53.00% |
Foreign Exchange Contract | Designated as Hedging Instrument | Purchase |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative, Notional Amount | € |  |  |  |  | € 64,555.3
Midwest premium swap contracts | Designated as Hedging Instrument | Purchase |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Derivative, Nonmonetary Notional Amount |  |  |  |  | 136.7

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- Definition Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition The percentage of expected requirements covered by the aggregate notional amount of derivative contracts expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract as a percentage of expected need. + References No definition available. + Details
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