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Segment and Related Information - Financial Information by Industry Segment (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 27, 2014	Sep. 27, 2014	Jun. 28, 2014	Mar. 29, 2014	Dec. 28, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Dec. 27, 2014	Dec. 28, 2013	Dec. 29, 2012
Net sales by segment:
Total consolidated net sales and net sales for reportable segments	$ 96,168us-gaap_SalesRevenueNet	$ 94,441us-gaap_SalesRevenueNet	$ 77,850us-gaap_SalesRevenueNet	$ 64,864us-gaap_SalesRevenueNet	$ 61,135us-gaap_SalesRevenueNet	$ 55,977us-gaap_SalesRevenueNet	$ 62,235us-gaap_SalesRevenueNet	$ 52,227us-gaap_SalesRevenueNet	$ 333,323us-gaap_SalesRevenueNet	$ 231,574us-gaap_SalesRevenueNet	$ 206,312us-gaap_SalesRevenueNet
Segment profit (loss):
Profit (loss) for reportable segments									16,628	(31,140)	(6,178)
Other unallocated amounts:
Corporate expenses									(7,530)	(5,977)	(7,785)
Interest and other from continuing operations, net									30us-gaap_InvestmentIncomeNet	54us-gaap_InvestmentIncomeNet	967us-gaap_InvestmentIncomeNet
Income (loss) from continuing operations before taxes									9,128	(37,063)	(12,996)
Depreciation and amortization by segment deducted in arriving at profit (loss):
Total Depreciation expense									5,438us-gaap_Depreciation	5,246us-gaap_Depreciation	5,158us-gaap_Depreciation
Intangible amortization									8,090us-gaap_AmortizationOfIntangibleAssets	8,082us-gaap_AmortizationOfIntangibleAssets	4,057us-gaap_AmortizationOfIntangibleAssets
Total depreciation and amortization for reportable segments									13,528	13,328	9,215
Capital expenditures by segment:
Total consolidated capital expenditures									1,660	3,874	3,240
Total assets by segment:
Total consolidated assets	348,818us-gaap_Assets				345,423us-gaap_Assets				348,818us-gaap_Assets	345,423us-gaap_Assets	334,873us-gaap_Assets
Discontinued operations					6,703					6,703	7,862
Operating Segments [Member]
Total assets by segment:
Total consolidated assets	333,037				319,331				333,037	319,331	303,808
Corporate, Non-Segment [Member]
Total assets by segment:
Corporate, principally cash and investments and deferred taxes	15,781				19,389				15,781	19,389	23,203
Semiconductor Equipment [Member]
Net sales by segment:
Total consolidated net sales and net sales for reportable segments									316,629	214,511	179,449
Segment profit (loss):
Profit (loss) for reportable segments									26,658	(24,998)	(5,331)
Depreciation and amortization by segment deducted in arriving at profit (loss):
Total Depreciation expense									4,805	4,723	4,506
Capital expenditures by segment:
Total consolidated capital expenditures									1,457	3,607	2,759
Semiconductor Equipment [Member] \| Operating Segments [Member]
Total assets by segment:
Total consolidated assets	320,102				297,175				320,102	297,175	281,173
Microwave Communications Equipment [Member]
Net sales by segment:
Total consolidated net sales and net sales for reportable segments									16,694	17,063	26,863
Segment profit (loss):
Profit (loss) for reportable segments									(10,030)	(6,142)	(847)
Depreciation and amortization by segment deducted in arriving at profit (loss):
Total Depreciation expense									633	523	652
Capital expenditures by segment:
Total consolidated capital expenditures									203	267	481
Microwave Communications Equipment [Member] \| Operating Segments [Member]
Total assets by segment:
Total consolidated assets	$ 12,935				$ 22,156				$ 12,935	$ 22,156	$ 22,635