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
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%