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 Stock [Member]
Business Acquisition [Line Items]
Number of Shares		150
Unit Price		$ 1,000,000.00
Amount	$ 150,000	$ 150,000
Common Stock [Member]
Business Acquisition [Line Items]
Number of Shares		139,397
Unit Price		$ 5,050.00
Amount		$ 703,955
Stock Options [Member]
Business Acquisition [Line Items]
Amount		$ 382