Description of the Business and Significant Accounting Policies (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015 segment item facility	Jun. 30, 2014
Segment Reporting Information
Number of reporting segments | segment			3
Steel Operations
Segment Reporting Information
Number of downstream coating facilities			8
Percentage of external net sales	69.00%	61.00%	68.00%	61.00%
Metals Recycling and Ferrous Resources Operations
Segment Reporting Information
Percentage of external net sales	23.00%	31.00%	23.00%	31.00%
Steel Fabrication Operations
Segment Reporting Information
Percentage of external net sales	8.00%	7.00%	8.00%	6.00%
Number of New Millennium Building Systems' joist and deck plants | item			6