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Preferred Share Issuance and Merger - Purchase Consideration (Details) - BCP IV GrafTech Holdings LP [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands | Aug. 11, 2015 | May. 18, 2015
--- | --- | ---
Business Acquisition [Line Items] |  |
Amount |  | $ 854,337
Convertible preferred equity - Series A and B |  |
Business Acquisition [Line Items] |  |
Shares |  | 150
Unit Price |  | $ 1,000,000
Amount | $ 150,000 | $ 150,000
Merger common equity - common shares |  |
Business Acquisition [Line Items] |  |
Shares |  | 139,397
Unit Price |  | $ 5,050
Amount |  | $ 703,955
Net value of options |  |
Business Acquisition [Line Items] |  |
Amount |  | $ 382

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