Revenue Recognition - Schedule of Disaggregated Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 46,362	$ 48,938	$ 154,594	$ 177,064
Point in Time | Restaurant/Retail
Disaggregation of Revenue [Line Items]
Revenue	22,452		83,673
Point in Time | Restaurant/Retail | Restaurant
Disaggregation of Revenue [Line Items]
Revenue	21,761		81,422
Point in Time | Restaurant/Retail | Grocery
Disaggregation of Revenue [Line Items]
Revenue	691		2,251
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	6,474		19,600
Over Time | Restaurant/Retail | Restaurant
Disaggregation of Revenue [Line Items]
Revenue	5,727		17,258
Over Time | Restaurant/Retail | Grocery
Disaggregation of Revenue [Line Items]
Revenue	747		2,342
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	17,436		51,321
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	8,283		25,324
Over Time | Government | ISR Solutions
Disaggregation of Revenue [Line Items]
Revenue	$ 9,153		$ 25,997