Annual report pursuant to Section 13 and 15(d)

Cover Page

Cover Page - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2021
Mar. 28, 2022
Jun. 30, 2021
Cover [Abstract]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 2021    
Current Fiscal Year End Date --12-31    
Document Transition Report false    
Entity File Number 0-19687    
Entity Registrant Name SYNALLOY CORPORATION    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 57-0426694    
Entity Address, Address Line One 4510 Cox Road,    
Entity Address, Address Line Two Suite 201,    
Entity Address, City or Town Richmond,    
Entity Address, State or Province VA    
Entity Address, Postal Zip Code 23060    
City Area Code (804)    
Local Phone Number 822-3260    
Title of 12(b) Security Common Stock, par value $1.00 per share    
Trading Symbol SYNL    
Security Exchange Name NASDAQ    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Non-accelerated Filer    
Entity Small Business true    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag false    
Entity Shell Company false    
Entity Public Float     $ 66.3
Entity Common Stock, Shares Outstanding   10,223,498  
Documents Incorporated by Reference
Documents Incorporated By Reference
Portions of the Proxy Statement for the 2022 annual shareholders' meeting are incorporated by reference into Part III of this Form 10-K.
Entity Central Index Key 0000095953    
Document Fiscal Year Focus 2021    
Document Fiscal Period Focus FY    
Amendment Flag false