Segment Reporting and Geographic Information (Details 3) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Dec. 31, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Net sales	$ 298,070	$ 297,193	$ 309,085	$ 303,467	$ 308,668	$ 294,268	$ 295,842	$ 240,669	$ 1,207,815	$ 1,139,447	$ 969,236
Consumer Electronics
Disaggregation of Revenue [Line Items]
Net sales									449,580
Industrial Components
Disaggregation of Revenue [Line Items]
Net sales									159,773
Energy
Disaggregation of Revenue [Line Items]
Net sales									118,734
Automotive Electronics
Disaggregation of Revenue [Line Items]
Net sales									80,484
Defense
Disaggregation of Revenue [Line Items]
Net sales									80,472
Medical
Disaggregation of Revenue [Line Items]
Net sales									91,101
Telecom Infrastructure
Disaggregation of Revenue [Line Items]
Net sales									67,022
Other End Market
Disaggregation of Revenue [Line Items]
Net sales									160,649
Performance Alloys and Composites
Disaggregation of Revenue [Line Items]
Net sales									500,590
Performance Alloys and Composites | Consumer Electronics
Disaggregation of Revenue [Line Items]
Net sales									103,339
Performance Alloys and Composites | Industrial Components
Disaggregation of Revenue [Line Items]
Net sales									101,646
Performance Alloys and Composites | Energy
Disaggregation of Revenue [Line Items]
Net sales									41,474
Performance Alloys and Composites | Automotive Electronics
Disaggregation of Revenue [Line Items]
Net sales									78,963
Performance Alloys and Composites | Defense
Disaggregation of Revenue [Line Items]
Net sales									45,162
Performance Alloys and Composites | Medical
Disaggregation of Revenue [Line Items]
Net sales									8,349
Performance Alloys and Composites | Telecom Infrastructure
Disaggregation of Revenue [Line Items]
Net sales									38,526
Performance Alloys and Composites | Other End Market
Disaggregation of Revenue [Line Items]
Net sales									83,131
Advanced Materials
Disaggregation of Revenue [Line Items]
Net sales									586,643
Advanced Materials | Consumer Electronics
Disaggregation of Revenue [Line Items]
Net sales									327,355
Advanced Materials | Industrial Components
Disaggregation of Revenue [Line Items]
Net sales									46,988
Advanced Materials | Energy
Disaggregation of Revenue [Line Items]
Net sales									77,248
Advanced Materials | Automotive Electronics
Disaggregation of Revenue [Line Items]
Net sales									0
Advanced Materials | Defense
Disaggregation of Revenue [Line Items]
Net sales									15,233
Advanced Materials | Medical
Disaggregation of Revenue [Line Items]
Net sales									17,627
Advanced Materials | Telecom Infrastructure
Disaggregation of Revenue [Line Items]
Net sales									28,437
Advanced Materials | Other End Market
Disaggregation of Revenue [Line Items]
Net sales									73,755
Precision Coatings
Disaggregation of Revenue [Line Items]
Net sales									120,582
Precision Coatings | Consumer Electronics
Disaggregation of Revenue [Line Items]
Net sales									18,886
Precision Coatings | Industrial Components
Disaggregation of Revenue [Line Items]
Net sales									11,139
Precision Coatings | Energy
Disaggregation of Revenue [Line Items]
Net sales									12
Precision Coatings | Automotive Electronics
Disaggregation of Revenue [Line Items]
Net sales									1,521
Precision Coatings | Defense
Disaggregation of Revenue [Line Items]
Net sales									20,077
Precision Coatings | Medical
Disaggregation of Revenue [Line Items]
Net sales									65,125
Precision Coatings | Telecom Infrastructure
Disaggregation of Revenue [Line Items]
Net sales									59
Precision Coatings | Other End Market
Disaggregation of Revenue [Line Items]
Net sales									3,763
Other
Disaggregation of Revenue [Line Items]
Net sales									0
Other | Consumer Electronics
Disaggregation of Revenue [Line Items]
Net sales									0
Other | Industrial Components
Disaggregation of Revenue [Line Items]
Net sales									0
Other | Energy
Disaggregation of Revenue [Line Items]
Net sales									0
Other | Automotive Electronics
Disaggregation of Revenue [Line Items]
Net sales									0
Other | Defense
Disaggregation of Revenue [Line Items]
Net sales									0
Other | Medical
Disaggregation of Revenue [Line Items]
Net sales									0
Other | Telecom Infrastructure
Disaggregation of Revenue [Line Items]
Net sales									0
Other | Other End Market
Disaggregation of Revenue [Line Items]
Net sales									$ 0