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Document And Entity Information	12 Months Ended
	Dec. 31, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	GrafTech International LTD.
Entity Central Index Key	0000931148
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	S-1
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Entity Small Business	false
Entity Emerging Growth Company	false

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Regulation 12B
-Number 240
-Section 12
-Subsection b-2

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Document and Entity Information[Abstract]

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