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Financial Instruments (Narrative) (Details) $ in Thousands, lb in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) lb	Dec. 31, 2019 USD ($) lb
Derivative [Line Items]
Annual Net Costs Mismatch Translation Exposure - Real vs US Dollar	$ 119,000
Net asset (liability)	$ (487)	$ (2,188)
Weight of aluminum that hedged future purchase of aluminum to meet fixed-price forward sales contract obligations, lbs | lb	13.0	19.6
Amounts of unrealized after-tax gains on derivative instruments	$ 1,200
Foreign Currency Cash Flow Hedge Derivative at Fair Value, Net	900
Line of credit facility, maximum borrowing capacity	375,000	$ 500,000
Aluminum Futures Contracts
Derivative [Line Items]
Derivative, Notional Amount, Net	12,100	$ 20,200
Prepaid Expenses and Other Current Assets [Member] | Aluminum Futures Contracts
Derivative [Line Items]
Net asset (liability)	$ 1,538

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Annual Net Costs Mismatch Translation Exposure - Real vs US Dollar

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Derivative, Notional Amount, Net

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The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
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Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments.

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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.

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Nominal mass used to calculate payments on a derivative instrument.

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Fair value as of the balance sheet date of all foreign currency derivatives designated as cash flow hedging instruments.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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