Derivative Financial Instruments and Related Hedging Programs, Notional Quantity Table (Details) - Dec. 31, 2016 mmlbs in Millions, $ in Millions	USD ($) MMBTU mmlbs	EUR (€) MMBTU mmlbs
Not Designated as Hedging Instrument \| Aluminum \| Purchase
Derivative [Line Items]
Derivative notional amount	149.0	149.0
Not Designated as Hedging Instrument \| Aluminum \| Sale
Derivative [Line Items]
Derivative notional amount	0.4	0.4
Not Designated as Hedging Instrument \| Midwest premium swap contracts \| Purchase
Derivative [Line Items]
Derivative notional amount	147.9	147.9
Not Designated as Hedging Instrument \| Natural Gas \| Purchase
Derivative [Line Items]
Derivative notional amount \| MMBTU	5,040,000	5,040,000
Designated as Hedging Instrument \| Alloy Metal Hedge \| Purchase
Derivative [Line Items]
Derivative notional amount	4.0	4.0
Designated as Hedging Instrument \| Foreign Exchange Contract \| Purchase
Derivative [Line Items]
Derivative, Notional Amount	$ 2.2	€ 1,593,700
Designated as Hedging Instrument \| Foreign Exchange Contract \| Sale
Derivative [Line Items]
Derivative, Notional Amount \| €		€ 633,600

- Definition

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

+ 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

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.

+ Details

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- Details

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