Segment Information, Narrative (Details) - productionfacilities	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Segment Reporting Information
Percentage of Employees Covered by Collective Bargaining Agreements	63.00%		63.00%
Percentage of Employees Covered by Collective Bargaining Agreements Expiring Within One Year	6.00%		6.00%
United States
Segment Reporting Information
Number of production facilities			11
Canada
Segment Reporting Information
Number of production facilities			1
Customer Concentration Risk | Largest Customer | Sales Revenue, Net | Fabricated Products
Segment Reporting Information
Concentration Risk, Percentage	25.00%	25.00%	26.00%	25.00%
Customer Concentration Risk | Largest Customer | Accounts Receivable
Segment Reporting Information
Concentration Risk, Percentage			16.00%
Customer Concentration Risk | Second Largest Customer | Sales Revenue, Net | Fabricated Products
Segment Reporting Information
Concentration Risk, Percentage	11.00%		10.00%
Customer Concentration Risk | Second Largest Customer | Accounts Receivable
Segment Reporting Information
Concentration Risk, Percentage			12.00%
Customer Concentration Risk | Third Largest Customer | Accounts Receivable
Segment Reporting Information
Concentration Risk, Percentage			10.00%
Customer Concentration Risk | Largest Customer (number 1) | Accounts Receivable
Segment Reporting Information
Concentration Risk, Percentage					17.00%
Customer Concentration Risk | Largest Customer (number 2) | Accounts Receivable
Segment Reporting Information
Concentration Risk, Percentage					17.00%