Business, Product and Geographical Area Information and Concentration of Risk, Narrative (Details) - productionfacilities	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Segment Reporting Information
Percentage of employees covered by collective bargaining agreements	62.00%
Percentage of employees covered by collective bargaining agreements expiring within one year	1.00%
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)	24.00%	27.00%
Customer Concentration Risk | Largest Customer | Accounts Receivable
Segment Reporting Information
Concentration percentages (percent)	29.00%		31.00%
Customer Concentration Risk | Second Largest Customer | Sales Revenue, Net
Segment Reporting Information
Concentration percentages (percent)	14.00%	13.00%
Customer Concentration Risk | Second Largest Customer | Accounts Receivable
Segment Reporting Information
Concentration percentages (percent)	13.00%		11.00%