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Cover
Nov. 16, 2020
May 06, 2020
Cover [Abstract]    
Entity Incorporation, State or Country Code DE  
Document Type 8-K  
Document Period End Date Nov. 16, 2020  
Entity Registrant Name GRAFTECH INTERNATIONAL LTD.  
Entity File Number 1-13888  
Entity Tax Identification Number 27-2496053  
Entity Address, Address Line One 982 Keynote Circle  
Entity Address, City or Town Brooklyn Heights  
Entity Address, State or Province OH  
Entity Address, Postal Zip Code 44131  
City Area Code 216  
Local Phone Number 676-2000  
Written Communications false  
Soliciting Material false  
Pre-commencement Tender Offer false  
Pre-commencement Issuer Tender Offer false  
Title of each class Common stock, $0.01 par value per share  
Trading Symbol(s) EAF  
Name of each exchange on which registered NYSE  
Entity Emerging Growth Company false  
Entity Central Index Key   0000931148
Amendment Flag   false