Business Segments, Geographic and Customer Information (Geographical Information) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net sales	$ 337,897	$ 367,959	$ 382,096
Long-lived assets	155,776	144,866
United States
Segment Reporting Information [Line Items]
Net sales	213,601	222,607	216,886
Long-lived assets	91,144	79,410
Germany
Segment Reporting Information [Line Items]
Net sales	76,273	89,247	107,137
Long-lived assets	48,492	52,264
Rest of Europe
Segment Reporting Information [Line Items]
Net sales	34,535	43,416	44,491
Long-lived assets	9,378	7,876
MEXICO
Segment Reporting Information [Line Items]
Net sales	9,085	8,762	8,365
Long-lived assets	3,435	1,830
Other
Segment Reporting Information [Line Items]
Net sales	4,403	3,927	$ 5,217
Long-lived assets	$ 3,327	$ 3,486