Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Nov. 06, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Trading Symbol	GLT
Entity Registrant Name	Glatfelter Corporation
Entity Central Index Key	0000041719
Current Fiscal Year End Date	--12-31
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity File Number	1-03560
Entity Tax Identification Number	23-0628360
Entity Address, Address Line One	4350 Congress Street
Entity Address, Address Line Two	Suite 600
Entity Address, City or Town	Charlotte
Entity Address, State or Province	NC
Entity Address, Postal Zip Code	28209
City Area Code	704
Entity Incorporation, State or Country Code	PA
Title of 12(b) Security	Common Stock
Document Transition Report	false
Document Quarterly Report	true
Security Exchange Name	NYSE
Local Phone Number	885-2555
Entity Common Stock, Shares Outstanding		44,367,836