Segment and Geographical Area Information, Narrative (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2015 productionfacilities customer	Dec. 31, 2014 customer	Dec. 31, 2013 customer
Segment Reporting Information
Percentage of Employees Covered by Collective Bargaining Agreements		63.00%
Percentage of Employees Covered by Collective Bargaining Agreements Expiring Within One Year		10.00%
United States
Segment Reporting Information
Number of production facilities | productionfacilities		11
Canada
Segment Reporting Information
Number of production facilities | productionfacilities		1
Customer Concentration Risk | Net sales | Largest Customer | Fabricated Products
Segment Reporting Information
Concentration risk, percentage		25.00%	22.00%	23.00%
Number of Customers | customer		1	1	1
Customer Concentration Risk | Net sales | Second Largest Customer | Fabricated Products
Segment Reporting Information
Concentration risk, percentage	10.00%	10.00%
Customer Concentration Risk | Trade Receivables | Largest Customer
Segment Reporting Information
Concentration risk, percentage			10.00%
Customer Concentration Risk | Trade Receivables | Second Largest Customer
Segment Reporting Information
Concentration risk, percentage		17.00%	12.00%
Number of Customers | customer		2	2