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Document And Entity Information - shares
 3 Months Ended
Mar. 31, 2021
Apr. 30, 2021
Document And Entity Information [Abstract]    
Entity Central Index Key 0000850429  
Current Fiscal Year End Date --12-31  
Entity Filer Category Accelerated Filer  
Document Fiscal Year Focus 2021  
Document Fiscal Period Focus (Q1,Q2,Q3,FY) Q1  
Amendment Flag 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  
Entity Registrant Name Tredegar Corporation  
Entity Common Stock, Shares Outstanding   33,677,433
Document Type 10-Q  
Document Quarterly Report true  
Entity Current Reporting Status Yes  
Entity Shell Company false  
Document Period End Date Mar. 31, 2021  
Document Transition Report false