Preferred Share Issuance and Merger (Narrative) (Details) - USD ($)	Aug. 11, 2015	May. 18, 2015	May. 17, 2015
Business Acquisition [Line Items]
Max Reimbursement to Acquiror	$ 500,000
Common stock, par value			$ 0.01
BCP IV GrafTech Holdings LP [Member]
Business Acquisition [Line Items]
Amount		$ 854,337,000
Convertible Preferred Stock [Member] | BCP IV GrafTech Holdings LP [Member]
Business Acquisition [Line Items]
Number of Shares		150,000
Amount	$ 150,000,000	$ 150,000,000
Convertible Preferred Stock [Member] | BCP IV GrafTech Holdings LP [Member] | Series A Preferred Stock [Member]
Business Acquisition [Line Items]
Number of Shares		136,616
Preferred stock, par value	$ 0.01
Business Combination, Equity Interest Transferred, Percentage of Common Stock Outstanding Before Transaction	19.90%
Convertible Preferred Stock [Member] | BCP IV GrafTech Holdings LP [Member] | Series B Preferred Stock [Member]
Business Acquisition [Line Items]
Number of Shares		13,384
Preferred stock, par value	$ 0.01
Notes Payable, Other Payables [Member] | Term Loan Facility [Member]
Business Acquisition [Line Items]
Debt Instrument, Unused Borrowing Capacity, Amount	$ 40,000,000
Senior Notes [Member] | Senior Subordinated Notes Due Nov 2015 [Member]
Business Acquisition [Line Items]
Early Repayment of Subordinated Debt	$ 200,000,000
Preferred Stock [Member]
Business Acquisition [Line Items]
Convertible Preferred Stock, Conversion Price			$ 5.05