Document And Entity Information - shares
9 Months Ended
Sep. 30, 2017
Oct. 26, 2017
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  
Document Period End Date Sep. 30, 2017  
Document Fiscal Year Focus 2017  
Document Fiscal Period Focus (Q1,Q2,Q3,FY) Q3  
Amendment Flag false  
Entity Common Stock, Shares Outstanding   33,026,931