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v3.20.1

Derivatives, Hedging Programs and Other Financial Instruments, Material Derivative Positions (Details) mmlbs in Millions | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 | Mar. 31, 2020 MMBTU euro MWH mmlbs
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Foreign Exchange Contract | Designated as Hedging Instrument | Purchase |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |
Derivative non-monetary notional amount | euro |  |  |  |  |  | 34,323,380
Electricity | Designated as Hedging Instrument | Purchase |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |
Derivative non-monetary notional amount | MWH |  |  |  |  |  | 613,820
Aluminum | Designated as Hedging Instrument | Purchase |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |
Derivative non-monetary notional amount |  |  |  |  |  | 115.3
Aluminum | Designated as Hedging Instrument | Sales |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |
Derivative non-monetary notional amount |  |  |  |  |  | 0.8
Midwest premium swap contracts | Designated as Hedging Instrument | Purchase |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |
Derivative non-monetary notional amount |  |  |  |  |  | 110.4
Alloy Metal Hedge | Designated as Hedging Instrument | Purchase |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |
Derivative non-monetary notional amount |  |  |  |  |  | 16.9
Natural Gas | Designated as Hedging Instrument | Purchase |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |
Derivative non-monetary notional amount | MMBTU |  |  |  |  |  | 7,970,000
Scenario, Forecast | Electricity |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage |  |  | 46.00% | 55.00% | 55.00% |
Scenario, Forecast | Natural Gas |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage | 75.00% | 80.00% | 80.00% | 76.00% | 75.00% |

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- Definition Nominal number of units used to calculate payment on derivative. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959 + Details
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