Industry Segments - Financial Information by Industry Segment (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 28, 2014	Jun. 29, 2013	Jun. 28, 2014	Jun. 29, 2013
Net sales by segment:
Consolidated net sales for reportable segments	$ 77,850	$ 62,234	$ 142,714	$ 114,461
Segment profit (loss):
Profit (loss) for reportable segments	2,682	(3,246)	1,318	(14,479)
Other unallocated amounts:
Corporate expenses	(1,637)	(1,650)	(3,697)	(3,553)
Interest and other, net	5	16	19	26
Income (loss) from continuing operations before taxes	1,050	(4,880)	(2,360)	(18,006)
Semiconductor Equipment [Member]
Net sales by segment:
Consolidated net sales for reportable segments	74,299	59,339	134,469	107,923
Segment profit (loss):
Profit (loss) for reportable segments	4,480	(605)	3,655	(9,466)
Microwave Communications Equipment [Member]
Net sales by segment:
Consolidated net sales for reportable segments	3,551	2,895	8,245	6,538
Segment profit (loss):
Profit (loss) for reportable segments	$ (1,798)	$ (2,641)	$ (2,337)	$ (5,013)