Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Narrative (Details)

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Summary of Significant Accounting Policies - Narrative (Details)
 12 Months Ended
Jan. 01, 2019
USD ($)
Jul. 01, 2018
Feb. 28, 2017
Dec. 31, 2019
USD ($)
subsidiaries
reporting_unit
segments
Dec. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Accounting Policies [Line Items]            
Number of operating segments | segments       2    
Number of reportable segments | segments       2    
Goodwill impairment       $ 0 $ 0  
Deferred charges and intangible assets       32,600,000 23,200,000  
Accumulated amortization on deferred charges       16,600,000 13,000,000  
Amortization expense       3,500,000 2,400,000 $ 2,400,000
Shipping costs       10,900,000 9,800,000 7,500,000
Research and development expense       600,000 500,000 $ 600,000
Total lease liabilities       37,285,000    
Right-of-use assets, operating leases, net       35,772,000 0  
Deferred tax assets       $ 790,000 253,000  
Accounting Standards Update 2016-02            
Accounting Policies [Line Items]            
Total lease liabilities $ 33,100,000          
Right-of-use assets, operating leases, net 32,200,000          
Cumulative adjustment         4,623,000  
Deferred tax assets 1,300,000          
Accounting Standards Update 2016-02 | Retained Earnings            
Accounting Policies [Line Items]            
Cumulative adjustment $ 4,600,000       4,623,000  
Software Licenses            
Accounting Policies [Line Items]            
Useful life of property, plant and equipment       5 years    
Customer List            
Accounting Policies [Line Items]            
Weighted average amortization period for intangible assets       13 years    
MUSA-Stainless | Customer List            
Accounting Policies [Line Items]            
Amortization period for intangible assets       15 years    
MUSA-Stainless | Earn-Out Payment            
Accounting Policies [Line Items]            
Contingent consideration earn-out period     4 years      
Earn out payments, target percentage     3.00%      
MUSA-Galvanized            
Accounting Policies [Line Items]            
Contingent consideration earn-out period   4 years        
Earn out payments, target percentage   3.00%        
MUSA-Galvanized | Customer List            
Accounting Policies [Line Items]            
Amortization period for intangible assets   15 years        
MUSA-Galvanized | Earn-Out Payment            
Accounting Policies [Line Items]            
Contingent consideration earn-out period   4 years        
Obsolescence Reserve            
Accounting Policies [Line Items]            
Inventory reserves       $ 300,000 300,000  
Physical Inventory Shrink Reserve            
Accounting Policies [Line Items]            
Inventory reserves       $ 400,000 $ 400,000  
Minimum            
Accounting Policies [Line Items]            
Accounts receivable, payment terms       30 days    
Amortization period for intangible assets       8 years    
Minimum | Land Improvement and Buildings            
Accounting Policies [Line Items]            
Useful life of property, plant and equipment       10 years    
Minimum | Machinery, Fixtures and Equipment            
Accounting Policies [Line Items]            
Useful life of property, plant and equipment       3 years    
Minimum | Deferred Charges            
Accounting Policies [Line Items]            
Amortization period for intangible assets       3 years    
Maximum            
Accounting Policies [Line Items]            
Accounts receivable, payment terms       60 days    
Amortization period for intangible assets       15 years    
Maximum | Land Improvement and Buildings            
Accounting Policies [Line Items]            
Useful life of property, plant and equipment       40 years    
Maximum | Machinery, Fixtures and Equipment            
Accounting Policies [Line Items]            
Useful life of property, plant and equipment       20 years    
Maximum | Deferred Charges            
Accounting Policies [Line Items]            
Amortization period for intangible assets       10 years    
American Stainless | American Stainless Tubing, Inc.            
Accounting Policies [Line Items]            
Contingent consideration earn-out period 3 years          
American Stainless | American Stainless Tubing, Inc. | Earn-Out Payment            
Accounting Policies [Line Items]            
Earn out payments, target percentage 6.50%          
Metals Segment            
Accounting Policies [Line Items]            
Number of reporting units | reporting_unit       3    
Number of subsidiaries | subsidiaries       4    
Metals Segment | Synalloy Metals, Inc.            
Accounting Policies [Line Items]            
Ownership percentage of subsidiary       100.00%    
Specialty Chemicals Segment            
Accounting Policies [Line Items]            
Number of reporting units | reporting_unit       1    
Number of subsidiaries | subsidiaries       2    
Specialty Chemicals Segment | Manufacturers Soap and Chemical Company            
Accounting Policies [Line Items]            
Ownership percentage of subsidiary       100.00%