Segment Information (Details)	12 Months Ended
	Dec. 31, 2014 item	Dec. 31, 2013	Dec. 31, 2012
Segment Information
Number of reportable segments	1
Sales (as a percent)	100.00%	100.00%	100.00%
Carbon steel
Segment Information
Sales (as a percent)	54.00%	53.00%	51.00%
Aluminum
Segment Information
Sales (as a percent)	15.00%	15.00%	15.00%
Stainless steel
Segment Information
Sales (as a percent)	14.00%	14.00%	15.00%
Alloy steel
Segment Information
Sales (as a percent)	9.00%	10.00%	12.00%
Toll processing
Segment Information
Sales (as a percent)	2.00%	2.00%	2.00%
Other
Segment Information
Sales (as a percent)	6.00%	6.00%	5.00%