Net Sales - Disaggregation of Net Sales (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Net sales	$ 337,897	$ 367,959	$ 382,096
United States
Disaggregation of Revenue [Line Items]
Net sales	213,601	222,607	216,886
Germany
Disaggregation of Revenue [Line Items]
Net sales	76,273	89,247	107,137
Rest of Europe
Disaggregation of Revenue [Line Items]
Net sales	34,535	43,416	44,491
MEXICO
Disaggregation of Revenue [Line Items]
Net sales	9,085	8,762	8,365
Other
Disaggregation of Revenue [Line Items]
Net sales	4,403	3,927
Finishing [Member]
Disaggregation of Revenue [Line Items]
Net sales	201,517	207,637
Finishing [Member] | United States
Disaggregation of Revenue [Line Items]
Net sales	77,529	68,384
Finishing [Member] | Germany
Disaggregation of Revenue [Line Items]
Net sales	76,273	89,247
Finishing [Member] | Rest of Europe
Disaggregation of Revenue [Line Items]
Net sales	34,535	37,317
Finishing [Member] | MEXICO
Disaggregation of Revenue [Line Items]
Net sales	9,074	8,762
Finishing [Member] | Other
Disaggregation of Revenue [Line Items]
Net sales	4,106	3,927
Engineered Components
Disaggregation of Revenue [Line Items]
Net sales	136,380	160,322	$ 159,129
Engineered Components | United States
Disaggregation of Revenue [Line Items]
Net sales	136,072	154,223
Engineered Components | Germany
Disaggregation of Revenue [Line Items]
Net sales	0	0
Engineered Components | Rest of Europe
Disaggregation of Revenue [Line Items]
Net sales	0	6,099
Engineered Components | MEXICO
Disaggregation of Revenue [Line Items]
Net sales	11	0
Engineered Components | Other
Disaggregation of Revenue [Line Items]
Net sales	297	0
Direct
Disaggregation of Revenue [Line Items]
Net sales	240,720	268,358
Direct | Finishing [Member]
Disaggregation of Revenue [Line Items]
Net sales	108,918	112,047
Direct | Engineered Components
Disaggregation of Revenue [Line Items]
Net sales	131,802	156,311
Distribution
Disaggregation of Revenue [Line Items]
Net sales	97,177	99,601
Distribution | Finishing [Member]
Disaggregation of Revenue [Line Items]
Net sales	92,599	95,590
Distribution | Engineered Components
Disaggregation of Revenue [Line Items]
Net sales	$ 4,578	$ 4,011