Concentrations of Risk (Details)	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015	Dec. 27, 2014
Concentration Risk [Line Items]
Concentrations of risk, percentage	10.00%
Accounts Receivable | Credit concentration risk | Elbit Systems
Concentration Risk [Line Items]
Concentrations of risk, percentage		21.00%
Accounts Receivable | Credit concentration risk | RealWear, Inc.
Concentration Risk [Line Items]
Concentrations of risk, percentage	10.00%
Accounts Receivable | Credit concentration risk | DRS Technologies
Concentration Risk [Line Items]
Concentrations of risk, percentage		19.00%
Accounts Receivable | Credit concentration risk | Scott Safety
Concentration Risk [Line Items]
Concentrations of risk, percentage	14.00%	18.00%
Accounts Receivable | Credit concentration risk | U.S. Army
Concentration Risk [Line Items]
Concentrations of risk, percentage	43.00%
Sales as a Percent of Total Revenue | Customer concentration risk | Raytheon Company
Concentration Risk [Line Items]
Concentrations of risk, percentage				18.00%
Sales as a Percent of Total Revenue | Customer concentration risk | DRS Technologies
Concentration Risk [Line Items]
Concentrations of risk, percentage	10.00%
Sales as a Percent of Total Revenue | Customer concentration risk | Google, Inc.
Concentration Risk [Line Items]
Concentrations of risk, percentage			22.00%
Sales as a Percent of Total Revenue | Customer concentration risk | Rockwell Collins
Concentration Risk [Line Items]
Concentrations of risk, percentage	10.00%	12.00%
Sales as a Percent of Total Revenue | Customer concentration risk | Shenzhen Oriscape
Concentration Risk [Line Items]
Concentrations of risk, percentage		20.00%
Sales as a Percent of Total Revenue | Customer concentration risk | Military Customers in Total
Concentration Risk [Line Items]
Concentrations of risk, percentage	48.00%	24.00%		32.00%
Sales as a Percent of Total Revenue | Customer concentration risk | U.S. Army
Concentration Risk [Line Items]
Concentrations of risk, percentage	12.00%
Sales as a Percent of Total Revenue | United States Government Funded Research and Development Contracts
Concentration Risk [Line Items]
Concentrations of risk, percentage	11.00%	7.00%		12.00%