Restructuring (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Restructuring Cost and Reserve [Line Items]
Restructuring (income) expense	$ (438)	$ 11,237	$ 785
Performance Alloys and Composites
Restructuring Cost and Reserve [Line Items]
Restructuring (income) expense	0	8,763	0
Advanced Materials
Restructuring Cost and Reserve [Line Items]
Restructuring (income) expense	0	0	0
Precision Optics
Restructuring Cost and Reserve [Line Items]
Restructuring (income) expense	(438)	2,052	328
Other
Restructuring Cost and Reserve [Line Items]
Restructuring (income) expense	$ 0	$ 422	$ 457