Cover - shares	9 Months Ended
	Sep. 30, 2021	Oct. 14, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	1-13888
Entity Registrant Name	GRAFTECH INTERNATIONAL LTD.
Entity Incorporation, State	DE
Entity Tax Identification Number	27-2496053
Entity Address, Street	982 Keynote Circle
Entity Address, City	Brooklyn Heights,
Entity Address, State	OH
Entity Address, Zip Code	44131
City Area Code	216
Local Phone Number	676-2000
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 Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		263,222,208
Amendment Flag	false
Document Period End Date	Sep. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Entity Central Index Key	0000931148
Current Fiscal Year End Date	--12-31