Segment Reporting (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 29, 2013	Mar. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Sales to external customers	$ 299,169	$ 353,630
Intersegment sales	1,478	1,826
Operating profit (loss)	9,522	9,884
Assets	812,400	796,310	814,917
Advanced Material Technologies [Member]
Segment Reporting Information [Line Items]
Sales to external customers	193,853	241,806
Intersegment sales	748	665
Operating profit (loss)	3,351	5,285
Assets	334,325	358,933
Performance Alloys [Member]
Segment Reporting Information [Line Items]
Sales to external customers	74,522	75,228
Intersegment sales	430	697
Operating profit (loss)	7,236	6,260
Assets	272,245	238,471
Beryllium and Composites [Member]
Segment Reporting Information [Line Items]
Sales to external customers	12,322	16,117
Intersegment sales	70	200
Operating profit (loss)	(1,296)	(1,291)
Assets	135,166	129,033
Technical Materials [Member]
Segment Reporting Information [Line Items]
Sales to external customers	18,472	20,400
Intersegment sales	230	264
Operating profit (loss)	1,436	1,893
Assets	23,417	24,560
Subtotal [Member]
Segment Reporting Information [Line Items]
Sales to external customers	299,169	353,551
Intersegment sales	1,478	1,826
Operating profit (loss)	10,727	12,147
Assets	765,153	750,997
All Other [Member]
Segment Reporting Information [Line Items]
Sales to external customers	0	79
Intersegment sales	0	0
Operating profit (loss)	(1,205)	(2,263)
Assets	$ 47,247	$ 45,313