Revenue Recognition - Schedule of Disaggregated Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 52,571	$ 62,261	$ 108,232	$ 128,126
Point in Time | Restaurant/Retail
Disaggregation of Revenue [Line Items]
Revenue	28,303		61,220
Point in Time | Restaurant/Retail | Restaurant
Disaggregation of Revenue [Line Items]
Revenue	27,430		59,594
Point in Time | Restaurant/Retail | Grocery
Disaggregation of Revenue [Line Items]
Revenue	873		1,626
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	6,524		13,127
Over Time | Restaurant/Retail | Restaurant
Disaggregation of Revenue [Line Items]
Revenue	5,742		11,599
Over Time | Restaurant/Retail | Grocery
Disaggregation of Revenue [Line Items]
Revenue	782		1,528
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	17,744		33,885
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	8,707		17,041
Over Time | Government | ISR Solutions
Disaggregation of Revenue [Line Items]
Revenue	$ 9,037		$ 16,844