Document and Entity Information - shares
9 Months Ended
Sep. 30, 2019
Nov. 08, 2019
Document and Entity Information [Abstract]    
Entity Registrant Name Synalloy Corporation  
Entity Central Index Key 0000095953  
Current Fiscal Year End Date --12-31  
Entity Filer Category Accelerated Filer  
Entity Common Stock, Shares Outstanding   9,033,855
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q3  
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Sep. 30, 2019  
Entity Current Reporting Status Yes  
Emerging Growth Company false  
Entity Shell Company false  
Smaller Reporting Company true