Document And Entity Information - shares	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Nov. 06, 2020
Document And Entity Information [Abstract]
Entity Registrant Name	Tredegar Corporation	TREDEGAR CORP
Entity Central Index Key		0000850429
Current Fiscal Year End Date		--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q	10-Q
Entity Emerging Growth Company		false
Entity Small Business		false
Entity Current Reporting Status	Yes	Yes
Entity Shell Company	false	false
Document Period End Date		Sep. 30, 2020
Document Fiscal Year Focus		2020
Document Fiscal Period Focus (Q1,Q2,Q3,FY)		Q3
Amendment Flag		false
Entity Common Stock, Shares Outstanding			33,497,768
Document Quarterly Report	true	true
Document Transition Report		false
Entity File Number	1-10258
Entity Incorporation, State or Country Code	VA
Entity Tax Identification Number	54-1497771
Entity Address, Address Line One	1100 Boulders Parkway
Entity Address, City or Town	Richmond,
Entity Address, State or Province	VA
Entity Address, Postal Zip Code	23225
City Area Code	(804)
Local Phone Number	330-1000
Title of 12(b) Security	Common stock, no par value
Trading Symbol	TG
Security Exchange Name	NYSE
Entity Interactive Data Current	Yes