Summary of Significant Accounting Policies (Details 3)	12 Months Ended
	Dec. 31, 2012 item	Dec. 31, 2011	Dec. 31, 2010
Segment Information
Number of reportable segments	1
Number of operating segments	1
Sales (as a percent)	100.00%	100.00%	100.00%
Carbon steel
Segment Information
Sales (as a percent)	51.00%	53.00%	52.00%
Aluminum
Segment Information
Sales (as a percent)	15.00%	15.00%	18.00%
Stainless steel
Segment Information
Sales (as a percent)	15.00%	15.00%	16.00%
Alloy steel
Segment Information
Sales (as a percent)	12.00%	10.00%	8.00%
Toll processing
Segment Information
Sales (as a percent)	2.00%	2.00%	2.00%
Other
Segment Information
Sales (as a percent)	5.00%	5.00%	4.00%