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Note 26 - Agreement to Build a Welded Pipe Plant in West Siberia (Details Textual) - Welded pipe plant in West Siberia [member]
$ in Millions
12 Months Ended
Feb. 05, 2019
USD ($)
t
Dec. 31, 2019
USD ($)
Statement Line Items [Line Items]    
Proportion of ownership interest in joint venture 49.00%  
Investments in joint ventures $ 280.0  
Manufacturing capacity, steel pipes (Metric Ton) | t 300,000  
Other cash payments to acquire interests in joint ventures   $ 19.6
PAO Severstal [member]    
Statement Line Items [Line Items]    
Proportion of ownership interest in joint venture 51.00%