Industry Segments - Financial Information by Industry Segment (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013
Net sales by segment:
Consolidated net sales for reportable segments	$ 94,441	$ 55,977	$ 237,155	$ 170,438
Segment profit (loss):
Profit (loss) for reportable segments	11,392	(10,902)	12,710	(25,381)
Other unallocated amounts:
Corporate expenses	(1,984)	(1,516)	(5,681)	(5,069)
Interest and other, net	6	16	25	42
Income (loss) from continuing operations before taxes	9,414	(12,402)	7,054	(30,408)
Semiconductor Equipment [Member]
Net sales by segment:
Consolidated net sales for reportable segments	91,573	52,403	226,042	160,326
Segment profit (loss):
Profit (loss) for reportable segments	13,928	(9,391)	17,583	(18,857)
Microwave Communications Equipment [Member]
Net sales by segment:
Consolidated net sales for reportable segments	2,868	3,574	11,113	10,112
Segment profit (loss):
Profit (loss) for reportable segments	$ (2,536)	$ (1,511)	$ (4,873)	$ (6,524)