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

+ Details

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- Definition

Nominal or face amount used to calculate payments on the derivative liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Notional Amount
-URI http://asc.fasb.org/extlink&oid=6519104

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5579245-113959

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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.

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Derivative Financial Instruments and Related Hedging Programs, Material Derivative Positions (Details)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2016 EUR (€) MMBTU mmlbs	Dec. 31, 2015 EUR (€)
Not Designated as Hedging Instrument \| Aluminum \| Purchase
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount					158.8
Not Designated as Hedging Instrument \| Aluminum \| Sales
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount					0.4
Not Designated as Hedging Instrument \| Natural Gas \| Purchase
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount \| MMBTU					5,650,000
Not Designated as Hedging Instrument \| Midwest premium swap contracts \| Purchase
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount					147.2
Designated as Hedging Instrument \| Foreign Currency \| Purchase
Derivative [Line Items]
Notional amount of contracts \| €					€ 1,593,700	€ 4,700,000
Scenario, Forecast [Member] \| Natural Gas
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage	33.00%	73.00%	74.00%	80.00%
Scenario, Forecast [Member] \| Electricity Member
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage	18.00%	54.00%	54.00%	55.00%