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Discontinued Operations and Related Assets Held for Sale (Narratives) (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Jun. 30, 2017 | Dec. 31, 2016 | Jun. 30, 2016 | Jun. 30, 2017 | Jun. 30, 2016 | Dec. 31, 2016 | Nov. 30, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |
Proceeds from Divestiture of Businesses |  |  |  | $ 28,500 |  | $ 15,900 |
Gain (Loss) on Disposition of Business |  |  |  |  |  | $ (200) |
Fiber Materials Inc. [Member] |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |
Potential Earnings in Disposed Entity |  |  |  |  |  |  | $ 8,500
Discontinued Operations, Held-for-sale [Member] | Engineered Solutions [Member] |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |
Impairment |  | $ 14,300 | $ 105,600 | $ 5,300 | $ 105,600 |  |
Gain (Loss) on Disposition of Business | $ 2,800 |  |  |  |  |  |

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