Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract.

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

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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.

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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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Derivatives, Hedging Programs and Other Financial Instruments, Material Derivative Positions (Details) mmlbs in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2017 EUR (€) MMBTU mmlbs
Not Designated as Hedging Instrument \| Option on Securities [Member] \| Purchase
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount				26.8
Not Designated as Hedging Instrument \| Aluminum \| Purchase
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount				205.8
Not Designated as Hedging Instrument \| Aluminum \| Sales
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount				1.4
Not Designated as Hedging Instrument \| Natural Gas \| Purchase
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount \| MMBTU				4,640,000.00
Not Designated as Hedging Instrument \| Midwest premium swap contracts [Member] \| Purchase
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount				203.5
Designated as Hedging Instrument \| Foreign Exchange Contract [Member] \| Purchase
Derivative [Line Items]
Derivative, Notional Amount \| €				€ 105,600
Designated as Hedging Instrument \| Alloy Metal Hedge [Member] \| Purchase
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount				5.7
Scenario, Forecast [Member] \| Natural Gas
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage	61.00%	72.00%	74.00%
Scenario, Forecast [Member] \| Electricity Member
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage			54.00%