Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2020	Nov. 01, 2019
Document And Entity Information [Abstract]
Entity Registrant Name	TREDEGAR CORP
Entity Central Index Key	0000850429
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Current Reporting Status	Yes
Entity Shell Company	false
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus (Q1,Q2,Q3,FY)	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		33,510,714
Document Quarterly Report	true
Document Transition Report	false