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Derivatives, Hedging Programs and Other Financial Instruments - Summary of Derivative Positions (Details) Mmlb in Millions | 9 Months Ended
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Sep. 30, 2023 GBP (£) MMBTU Mmlb EUR (€) MWh
Purchase | Euro |
Derivative [Line Items] |
Derivative non-monetary notional amount | € | 3,047,291
Purchase | British Pounds |
Derivative [Line Items] |
Derivative non-monetary notional amount | £ | 393,693
Purchase | Minimum | Euro |
Derivative [Line Items] |
Derivative maturity period | Oct. 31, 2023
Purchase | Minimum | British Pounds |
Derivative [Line Items] |
Derivative maturity period | Nov. 30, 2023
Purchase | Maximum | Euro |
Derivative [Line Items] |
Derivative maturity period | Jun. 30, 2024
Purchase | Maximum | British Pounds |
Derivative [Line Items] |
Derivative maturity period | May 31, 2024
Purchase | Natural Gas |
Derivative [Line Items] |
Derivative non-monetary notional amount | MMBTU | 3,130,000
Purchase | Natural Gas | Minimum |
Derivative [Line Items] |
Derivative maturity period | Oct. 31, 2023
Purchase | Natural Gas | Maximum |
Derivative [Line Items] |
Derivative maturity period | Dec. 31, 2026
Purchase | Aluminum |
Derivative [Line Items] |
Derivative non-monetary notional amount | 101.4
Purchase | Aluminum | Minimum |
Derivative [Line Items] |
Derivative maturity period | Oct. 31, 2023
Purchase | Aluminum | Maximum |
Derivative [Line Items] |
Derivative maturity period | Dec. 31, 2025
Purchase | Alloying Metals |
Derivative [Line Items] |
Derivative non-monetary notional amount | 3.7
Purchase | Alloying Metals | Minimum |
Derivative [Line Items] |
Derivative maturity period | Oct. 31, 2023
Purchase | Alloying Metals | Maximum |
Derivative [Line Items] |
Derivative maturity period | Dec. 31, 2025
Purchase | Fixed Price Purchase Contracts for Midwest Premium |
Derivative [Line Items] |
Derivative non-monetary notional amount | 85.4
Purchase | Fixed Price Purchase Contracts for Midwest Premium | Minimum |
Derivative [Line Items] |
Derivative maturity period | Oct. 31, 2023
Purchase | Fixed Price Purchase Contracts for Midwest Premium | Maximum |
Derivative [Line Items] |
Derivative maturity period | Dec. 31, 2025
Purchase | Electricity |
Derivative [Line Items] |
Derivative non-monetary notional amount | MWh | 35,136
Purchase | Electricity | Minimum |
Derivative [Line Items] |
Derivative maturity period | Jan. 31, 2024
Purchase | Electricity | Maximum |
Derivative [Line Items] |
Derivative maturity period | Dec. 31, 2024
Sales | Aluminum |
Derivative [Line Items] |
Derivative non-monetary notional amount | 29.7
Sales | Aluminum | Minimum |
Derivative [Line Items] |
Derivative maturity period | Oct. 31, 2023
Sales | Aluminum | Maximum |
Derivative [Line Items] |
Derivative maturity period | Apr. 30, 2024
Sales | Fixed Price Sale Contracts for Midwest Premium |
Derivative [Line Items] |
Derivative non-monetary notional amount | 48.9
Sales | Fixed Price Sale Contracts for Midwest Premium | Minimum |
Derivative [Line Items] |
Derivative maturity period | Oct. 31, 2023
Sales | Fixed Price Sale Contracts for Midwest Premium | Maximum |
Derivative [Line Items] |
Derivative maturity period | May 31, 2024

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