Summary of Significant Accounting Policies (Schedule of Reclassifications Out of AOCI) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Selling, general and administrative		$ 94,352		$ 85,283		$ 83,386
Income tax expense (benefit)	[1]	9,913		11,526		(53,163)
Gain (loss) on derivative financial instruments | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total, before taxes		(3,578)		(665)		1,229
Income tax expense (benefit)		(598)		253		287
Total, net of tax		(2,980)		(918)		942
Pension and other post-retirement benefit adjustments | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Actuarial gain (loss) and prior service costs, before taxes		(10,632)	[2]	(13,650)	[2]	(12,045)
Income tax expense (benefit)		(2,359)		(3,028)		(4,234)
Total, net of tax		(8,273)		(10,622)		(7,811)
Aluminum Futures Contracts | Gain (loss) on derivative financial instruments | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of Goods and Services Sold		(2,736)		1,069		1,210
Foreign Currency Forward Contracts | Gain (loss) on derivative financial instruments | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of Goods and Services Sold		62		62		62
Selling, general and administrative						$ (43)
Selling, General and Administrative Expenses [Member] | Foreign Currency Forward Contracts | Gain (loss) on derivative financial instruments | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of Goods and Services Sold		$ 904		$ 1,796

[1] See Notes 1, 3, 4 and 17 for more information on losses associated with plant shutdowns, asset impairments and restructurings, unusual items, gains or losses from sale of assets, gains or losses on an investment accounted for under the fair value method and other items.

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