Segment Reporting (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 26, 2020	Jun. 28, 2019	Jun. 26, 2020	Jun. 28, 2019
Segment Reporting Information
Net sales	$ 271,468,000	$ 297,843,000	$ 549,414,000	$ 599,284,000
Intersegment sales	8,784,000	19,266,000	18,190,000	36,488,000
Operating profit	8,706,000	22,750,000	4,143,000	44,137,000
Performance Alloys and Composites
Segment Reporting Information
Net sales	101,614,000	135,231,000	200,681,000	262,344,000
Intersegment sales	(213,000)	6,000	2,000	15,000
Operating profit	8,244,000	19,328,000	13,035,000	38,286,000
Advanced Materials
Segment Reporting Information
Net sales	150,108,000	133,238,000	310,273,000	277,263,000
Intersegment sales	8,997,000	19,260,000	18,188,000	36,473,000
Operating profit	4,370,000	6,139,000	9,155,000	13,219,000
Precision Coatings
Segment Reporting Information
Net sales	19,746,000	29,374,000	38,460,000	59,677,000
Intersegment sales	0	0	0	0
Operating profit	2,091,000	3,937,000	(7,501,000)	6,014,000
Other
Segment Reporting Information
Net sales	0	0	0	0
Intersegment sales	0	0	0	0
Operating profit	$ (5,999,000)	$ (6,654,000)	$ (10,546,000)	$ (13,382,000)