Segment Reporting (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 29, 2019	Mar. 30, 2018
Segment Reporting Information
Net sales	$ 301,441	$ 303,467
Intersegment sales	17,222	11,680
Operating profit (loss)	21,387	13,251
Performance Alloys and Composites
Segment Reporting Information
Net sales	127,113	118,236
Intersegment sales	9	28
Operating profit (loss)	18,958	9,861
Advanced Materials
Segment Reporting Information
Net sales	144,025	153,545
Intersegment sales	17,213	11,652
Operating profit (loss)	7,080	5,898
Precision Coatings
Segment Reporting Information
Net sales	30,303	31,686
Intersegment sales	0	0
Operating profit (loss)	2,077	3,375
Other
Segment Reporting Information
Net sales	0	0
Intersegment sales	0	0
Operating profit (loss)	$ (6,728)	$ (5,883)