Discontinued Operations - Schedule of Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 05, 2015	Jun. 29, 2014	Jul. 05, 2015	Jun. 29, 2014	Dec. 31, 2014
Assets and Liabilities
Held for sale assets	$ 38,927		$ 38,927		$ 29,814
Held for sale liabilities	14,598		14,598		12,191
Revenue and Expenses
Income from discontinued operations, net	198	$ 3,273	1,228	$ 3,963
Significant Noncash Items
Capital expenditures			482	261
SISD | Discontinued Operations, Held-for-sale
Assets and Liabilities
Accounts receivable, net	9,550		9,550		10,885
Inventories, net	5,943		5,943		6,313
Unbilled revenue	2,573		2,573		2,356
Prepaid expenses and other current assets	3,391		3,391		2,955
Property, plant, and equipment, net	1,720		1,720		1,944
Intangible assets, net	11,338		11,338		1,029
Goodwill	4,301		4,301		4,301
Other assets	111		111		31
Held for sale assets	38,927		38,927		29,814
Accounts payable	1,470		1,470		1,891
Accrued expenses	3,787		3,787		4,335
Deferred revenue	9,341		9,341		5,965
Held for sale liabilities	14,598		14,598		$ 12,191
Revenue and Expenses
Revenue	11,187	16,526	23,248	26,139
Cost of revenue	(5,765)	(7,506)	(11,291)	(11,948)
Research, development, and engineering expenses	1,022	1,118	2,126	2,068
Selling, general, and administrative expenses	(4,176)	(3,204)	(7,800)	(6,384)
Foreign currency gain (loss)	77	(22)	(177)	(22)
Pretax income from discontinued operations	301	4,676	1,854	5,717
Income tax expense	103	1,403	626	1,754
Income from discontinued operations, net	198	3,273	1,228	3,963
Significant Noncash Items
Capital expenditures	171	152	482	261
Stock-based compensation expense	144	248	427	555
Depreciation expense	203	193	401	388
Amortization expense	$ 82	$ 94	$ 165	$ 188