Description of the Business and Significant Accounting Policies (Segments) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Steel Operations
Segment Reporting Information
Percentage of external net sales	73.00%	74.00%	73.00%	72.00%
Metals Recycling Operations
Segment Reporting Information
Percentage of external net sales	14.00%	15.00%	15.00%	15.00%
Steel Fabrication Operations
Segment Reporting Information
Percentage of external net sales	9.00%	8.00%	8.00%	9.00%