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Goodwill and Other Intangible Assets - Goodwill (Details) - USD ($) |  | 3 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jul. 12, 2018 | Sep. 30, 2017 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Goodwill [Line Items] |  |  |  |  |
Goodwill |  |  | $ 534,700,000 | $ 531,400,000 |
Period increase (decrease) in goodwill |  |  | 3,300,000 |  |
Impairment of goodwill |  | $ (114,400,000) | 0 | (114,400,000) | $ 0
Accumulated goodwill impairment |  |  | 241,000,000 | 241,000,000 |
Addaero Manufacturing [Member] |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |
Goodwill |  |  | 6,000,000 |  |
Payments to Acquire Businesses, Gross | $ 10,000,000 |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles |  |  | 2,000,000 |  |
High Performance Materials & Components |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |
Goodwill |  |  | 534,700,000 |  |
Impairment of goodwill |  |  | 0 | $ (114,400,000) | $ 0
Goodwill, Foreign Currency Translation Gain (Loss) |  |  | $ (2,700,000) |  |
High Performance Materials & Components | First Reporting Unit [Member] |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |
Percentage of fair value in excess of carrying value |  |  |  |  | 12.00%

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