Segment Reporting and Geographic Information - Reportable Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Net sales	$ 1,510,644	$ 1,176,274	$ 1,185,424
Operating profit (loss)	77,111	8,215	70,546
Depreciation, depletion, and amortization	44,137	42,384	41,116
Expenditures for long-lived assets	102,910	67,274	26,528
Total assets	1,607,479	1,057,860	898,430
Performance Alloys and Composites
Segment Reporting Information [Line Items]
Net sales	511,874	394,195
Operating profit (loss)	67,908	13,597	73,815
Depreciation, depletion, and amortization	21,685	25,782	24,437
Expenditures for long-lived assets	82,987	53,841	15,520
Total assets	636,182	477,892	442,885
Advanced Materials
Segment Reporting Information [Line Items]
Net sales	866,816	670,867
Operating profit (loss)	35,330	22,120	25,124
Depreciation, depletion, and amortization	9,602	8,061	8,955
Expenditures for long-lived assets	10,780	9,003	7,572
Total assets	653,595	251,637	214,961
Precision Optics
Segment Reporting Information [Line Items]
Net sales	131,954	111,212
Operating profit (loss)	14,185	(4,382)	(3,550)
Depreciation, depletion, and amortization	10,883	6,564	5,695
Expenditures for long-lived assets	7,523	908	1,045
Total assets	252,711	268,004	78,981
Other
Segment Reporting Information [Line Items]
Net sales	0	0
Operating profit (loss)	(40,312)	(23,120)	(24,843)
Depreciation, depletion, and amortization	1,967	1,977	2,029
Expenditures for long-lived assets	1,620	3,522	2,391
Total assets	64,991	60,327	161,603
Operating Segments
Segment Reporting Information [Line Items]
Net sales	1,510,644	1,176,274	1,185,424
Operating Segments | Performance Alloys and Composites
Segment Reporting Information [Line Items]
Net sales	511,874	394,195	500,201
Operating Segments | Advanced Materials
Segment Reporting Information [Line Items]
Net sales	866,816	670,867	573,763
Operating Segments | Precision Optics
Segment Reporting Information [Line Items]
Net sales	131,954	111,212	111,460
Operating Segments | Other
Segment Reporting Information [Line Items]
Net sales	0	0	0
Intersegment Eliminations
Segment Reporting Information [Line Items]
Net sales	14,052	35,918	70,085
Intersegment Eliminations | Performance Alloys and Composites
Segment Reporting Information [Line Items]
Net sales	172	6	38
Intersegment Eliminations | Advanced Materials
Segment Reporting Information [Line Items]
Net sales	13,880	35,912	70,047
Intersegment Eliminations | Precision Optics
Segment Reporting Information [Line Items]
Net sales	0	0	0
Intersegment Eliminations | Other
Segment Reporting Information [Line Items]
Net sales	$ 0	$ 0	$ 0