Preferred Share Issuance and Merger (Details) - USD ($)			3 Months Ended	9 Months Ended
	Aug. 11, 2015	May 18, 2015	Sep. 30, 2015	Sep. 30, 2016	Dec. 31, 2015	Aug. 15, 2015	May 17, 2015
Goodwill				$ 171,117,000	$ 172,059,000
Max Reimbursement to Acquiror			$ 500,000
Common Stock, Par or Stated Value Per Share							$ 0.01
Goodwill, Purchase Accounting Adjustments				1,100,000
purchase price adjustment, deferred taxes				$ 2,000,000
Preferred Stock [Member]
Convertible Preferred Stock, Conversion Price							$ 5.05
BCP IV GrafTech Holdings LP [Member]
Goodwill						$ 173,117,000
Amount		$ 854,337,000
Convertible Preferred Stock [Member] | BCP IV GrafTech Holdings LP [Member]
Shares		150,000
Amount	$ 150,000,000	$ 150,000,000
Series A Preferred Stock [Member] | Convertible Preferred Stock [Member] | BCP IV GrafTech Holdings LP [Member]
Shares		136,616
Preferred stock, par value	$ 0.01
Business Combination, Equity Interest Transferred, Percentage of Common Stock Outstanding Before Transaction	19.90%
Series B Preferred Stock [Member] | Convertible Preferred Stock [Member] | BCP IV GrafTech Holdings LP [Member]
Shares		13,384
Preferred stock, par value	$ 0.01
Delayed draw term loan facility | Term Loan Facility
Unused borrowing capacity	$ 40,000,000
Senior Notes | Senior Subordinated Notes Due Nov 2015 [Member]
Early Repayment of Subordinated Debt	$ 200,000,000