Revenue Recognition - Schedule of Disaggregated Revenue (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 44,682,000	$ 55,661,000
Point in Time | Restaurant/Retail
Disaggregation of Revenue [Line Items]
Revenue	22,826,000	32,917,000
Point in Time | Restaurant/Retail | Restaurant
Disaggregation of Revenue [Line Items]
Revenue	22,336,000	32,164,000
Point in Time | Restaurant/Retail | Grocery
Disaggregation of Revenue [Line Items]
Revenue	490,000	753,000
Point in Time | Restaurant/Retail | Mission Systems
Disaggregation of Revenue [Line Items]
Revenue	0	0
Point in Time | Restaurant/Retail | ISR Solutions
Disaggregation of Revenue [Line Items]
Revenue	0	0
Over Time | Restaurant/Retail
Disaggregation of Revenue [Line Items]
Revenue	6,734,000	6,603,000
Over Time | Restaurant/Retail | Restaurant
Disaggregation of Revenue [Line Items]
Revenue	5,790,000	5,857,000
Over Time | Restaurant/Retail | Grocery
Disaggregation of Revenue [Line Items]
Revenue	944,000	746,000
Over Time | Restaurant/Retail | Mission Systems
Disaggregation of Revenue [Line Items]
Revenue	0	0
Over Time | Restaurant/Retail | ISR Solutions
Disaggregation of Revenue [Line Items]
Revenue	0	0
Over Time | Government
Disaggregation of Revenue [Line Items]
Revenue	15,122,000	16,141,000
Over Time | Government | Restaurant
Disaggregation of Revenue [Line Items]
Revenue	0	0
Over Time | Government | Grocery
Disaggregation of Revenue [Line Items]
Revenue	0	0
Over Time | Government | Mission Systems
Disaggregation of Revenue [Line Items]
Revenue	8,546,000	8,334,000
Over Time | Government | ISR Solutions
Disaggregation of Revenue [Line Items]
Revenue	$ 6,576,000	$ 7,807,000