Segment Information (Income by Reportable Segments) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Net sales	$ 214,611	$ 203,828
Operating income	31,044	39,037
Equity income in unconsolidated joint ventures	1,007	1,009
Other income (expense), net	66	1,119
Interest expense, net	(1,210)	(1,248)
Income before income tax expense	30,907	39,917
Advanced Connectivity Solutions
Segment Reporting Information [Line Items]
Net sales	73,455	78,528
Operating income	7,903	19,498
Elastomeric Material Solutions
Segment Reporting Information [Line Items]
Net sales	78,083	76,864
Operating income	14,159	12,790
Power Electronics Solutions
Segment Reporting Information [Line Items]
Net sales	57,714	42,652
Operating income	7,021	4,844
Other
Segment Reporting Information [Line Items]
Net sales	5,359	5,784
Operating income	1,961	1,905
Recognized over time
Segment Reporting Information [Line Items]
Net sales	63,087	48,036
Recognized over time | Advanced Connectivity Solutions
Segment Reporting Information [Line Items]
Net sales	0	0
Recognized over time | Elastomeric Material Solutions
Segment Reporting Information [Line Items]
Net sales	1,039	667
Recognized over time | Power Electronics Solutions
Segment Reporting Information [Line Items]
Net sales	57,400	42,273
Recognized over time | Other
Segment Reporting Information [Line Items]
Net sales	4,648	5,096
Recognized at a point in time
Segment Reporting Information [Line Items]
Net sales	151,524	155,792
Recognized at a point in time | Advanced Connectivity Solutions
Segment Reporting Information [Line Items]
Net sales	73,455	78,528
Recognized at a point in time | Elastomeric Material Solutions
Segment Reporting Information [Line Items]
Net sales	77,044	76,197
Recognized at a point in time | Power Electronics Solutions
Segment Reporting Information [Line Items]
Net sales	314	379
Recognized at a point in time | Other
Segment Reporting Information [Line Items]
Net sales	711	688
Segment Reconciling Items
Segment Reporting Information [Line Items]
Equity income in unconsolidated joint ventures	1,007	1,009
Other income (expense), net	66	1,119
Interest expense, net	(1,210)	(1,248)
United States
Segment Reporting Information [Line Items]
Net sales	59,805	61,129
United States | Advanced Connectivity Solutions
Segment Reporting Information [Line Items]
Net sales	12,278	13,220
United States | Elastomeric Material Solutions
Segment Reporting Information [Line Items]
Net sales	37,692	38,104
United States | Power Electronics Solutions
Segment Reporting Information [Line Items]
Net sales	8,578	8,590
United States | Other
Segment Reporting Information [Line Items]
Net sales	1,257	1,215
Other Americas
Segment Reporting Information [Line Items]
Net sales	2,815	3,526
Other Americas | Advanced Connectivity Solutions
Segment Reporting Information [Line Items]
Net sales	826	567
Other Americas | Elastomeric Material Solutions
Segment Reporting Information [Line Items]
Net sales	1,801	2,472
Other Americas | Power Electronics Solutions
Segment Reporting Information [Line Items]
Net sales	358	303
Other Americas | Other
Segment Reporting Information [Line Items]
Net sales	(170)	184
Total Americas
Segment Reporting Information [Line Items]
Net sales	62,620	64,655
Total Americas | Advanced Connectivity Solutions
Segment Reporting Information [Line Items]
Net sales	13,104	13,787
Total Americas | Elastomeric Material Solutions
Segment Reporting Information [Line Items]
Net sales	39,493	40,576
Total Americas | Power Electronics Solutions
Segment Reporting Information [Line Items]
Net sales	8,936	8,893
Total Americas | Other
Segment Reporting Information [Line Items]
Net sales	1,087	1,399
China
Segment Reporting Information [Line Items]
Net sales	65,040	62,047
China | Advanced Connectivity Solutions
Segment Reporting Information [Line Items]
Net sales	33,507	37,423
China | Elastomeric Material Solutions
Segment Reporting Information [Line Items]
Net sales	20,794	16,915
China | Power Electronics Solutions
Segment Reporting Information [Line Items]
Net sales	9,422	6,367
China | Other
Segment Reporting Information [Line Items]
Net sales	1,317	1,342
Other APAC
Segment Reporting Information [Line Items]
Net sales	31,742	31,902
Other APAC | Advanced Connectivity Solutions
Segment Reporting Information [Line Items]
Net sales	15,338	15,924
Other APAC | Elastomeric Material Solutions
Segment Reporting Information [Line Items]
Net sales	9,160	9,944
Other APAC | Power Electronics Solutions
Segment Reporting Information [Line Items]
Net sales	6,451	5,119
Other APAC | Other
Segment Reporting Information [Line Items]
Net sales	793	915
Total APAC
Segment Reporting Information [Line Items]
Net sales	96,782	93,949
Total APAC | Advanced Connectivity Solutions
Segment Reporting Information [Line Items]
Net sales	48,845	53,347
Total APAC | Elastomeric Material Solutions
Segment Reporting Information [Line Items]
Net sales	29,954	26,859
Total APAC | Power Electronics Solutions
Segment Reporting Information [Line Items]
Net sales	15,873	11,486
Total APAC | Other
Segment Reporting Information [Line Items]
Net sales	2,110	2,257
Germany
Segment Reporting Information [Line Items]
Net sales	23,871	20,486
Germany | Advanced Connectivity Solutions
Segment Reporting Information [Line Items]
Net sales	6,250	6,075
Germany | Elastomeric Material Solutions
Segment Reporting Information [Line Items]
Net sales	2,742	2,293
Germany | Power Electronics Solutions
Segment Reporting Information [Line Items]
Net sales	14,710	11,935
Germany | Other
Segment Reporting Information [Line Items]
Net sales	169	183
Other EMEA
Segment Reporting Information [Line Items]
Net sales	31,338	24,738
Other EMEA | Advanced Connectivity Solutions
Segment Reporting Information [Line Items]
Net sales	5,256	5,319
Other EMEA | Elastomeric Material Solutions
Segment Reporting Information [Line Items]
Net sales	5,894	7,136
Other EMEA | Power Electronics Solutions
Segment Reporting Information [Line Items]
Net sales	18,195	10,338
Other EMEA | Other
Segment Reporting Information [Line Items]
Net sales	1,993	1,945
Total EMEA
Segment Reporting Information [Line Items]
Net sales	55,209	45,224
Total EMEA | Advanced Connectivity Solutions
Segment Reporting Information [Line Items]
Net sales	11,506	11,394
Total EMEA | Elastomeric Material Solutions
Segment Reporting Information [Line Items]
Net sales	8,636	9,429
Total EMEA | Power Electronics Solutions
Segment Reporting Information [Line Items]
Net sales	32,905	22,273
Total EMEA | Other
Segment Reporting Information [Line Items]
Net sales	$ 2,162	$ 2,128