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Summary of Significant Accounting Policies (Schedule of Reclassifications Out of AOCI) (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] |  |  |  |  |  |
Cost of goods sold |  | $ (668,626) |  | $ (725,459) |  | $ (778,113)
Income taxes | [1] | 3,217 |  | 8,928 |  | 9,387
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 |  | (1,568) |  | (3,476) |  | 647
Income taxes |  | (579) |  | (1,284) |  | 244
Total, net of tax |  | (989) |  | (2,192) |  | 403
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 |  | (13,098) | [2] | (16,041) | [2] | (10,579)
Income taxes |  | (4,398) |  | (5,823) |  | (3,582)
Total, net of tax |  | (8,700) |  | (10,218) |  | (6,997)
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 sold |  | (1,630) |  | (3,538) |  | (631)
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 sold |  | $ 62 |  | $ 62 |  | $ (16)
[1] | See Notes 1, 3, 4 and 18 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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