Description of the Business and Significant Accounting Policies (Segments) (Details)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Steel Operations
Segment Reporting Information
Percentage of external net sales	74.00%	73.00%
Metals Recycling Operations
Segment Reporting Information
Percentage of external net sales	15.00%	15.00%
Steel Fabrication Operations
Segment Reporting Information
Percentage of external net sales	8.00%	8.00%