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Cover
Dec. 18, 2020
Dec. 17, 2020
Cover [Abstract]    
Document Type 8-K  
Document Period End Date Dec. 18, 2020  
Entity Registrant Name Tredegar Corporation  
Entity Incorporation, State or Country Code VA  
Entity File Number 1-10258  
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  
Written Communications false  
Soliciting Material false  
Pre-commencement Tender Offer false  
Pre-commencement Issuer Tender Offer false  
Title of 12(b) Security Common stock, no par value  
Trading Symbol TG  
Security Exchange Name NYSE  
Entity Emerging Growth Company false  
Entity Ex Transition Period false  
Document Information [Line Items]    
Entity Central Index Key 0000850429  
Document Fiscal Year Focus 2020  
Document Fiscal Period Focus Q3  
Amendment Flag false  
Document Period End Date Dec. 18, 2020  
Document Period Start Date   Dec. 17, 2020