Description of the Business and Significant Accounting Policies (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015 segment item facility	Sep. 30, 2014
Segment Reporting Information
Number of reporting segments | segment			3
Steel Operations
Segment Reporting Information
Number of downstream coating facilities | facility			8
Percentage of external net sales	69.00%	62.00%	69.00%	61.00%
Metals Recycling Operations
Segment Reporting Information
Percentage of external net sales	18.00%	26.00%	19.00%	27.00%
Steel Fabrication Operations
Segment Reporting Information
Percentage of external net sales	9.00%	8.00%	8.00%	7.00%
Number of New Millennium Building Systems' joist and deck plants			8