Document And Entity Information - shares
3 Months Ended
Mar. 31, 2019
May 03, 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  
Document Period End Date Mar. 31, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus (Q1,Q2,Q3,FY) Q1  
Amendment Flag false  
Entity Common Stock, Shares Outstanding   33,351,452