Business, Product and Geographical Area Information and Concentration of Risk, Narrative (Details) - productionfacilities	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information
Percentage of employees covered by collective bargaining agreements	61.00%		61.00%
Percentage of employees covered by collective bargaining agreements expiring within one year	0.00%		0.00%
Domestic
Segment Reporting Information
Number of production facilities			12
Foreign
Segment Reporting Information
Number of production facilities			1
Customer Concentration Risk | Largest Customer | Sales Revenue, Net
Segment Reporting Information
Concentration percentages (percent)	26.00%	27.00%	26.00%	28.00%
Customer Concentration Risk | Largest Customer | Accounts Receivable
Segment Reporting Information
Concentration percentages (percent)			24.00%		22.00%
Customer Concentration Risk | Second Largest Customer | Sales Revenue, Net
Segment Reporting Information
Concentration percentages (percent)	15.00%	11.00%	13.00%	10.00%
Customer Concentration Risk | Second Largest Customer | Accounts Receivable
Segment Reporting Information
Concentration percentages (percent)			15.00%		14.00%