Revenue Recognition - Schedule of Disaggregated Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 54,732	$ 44,682
Billed | Restaurant/Retail
Disaggregation of Revenue [Line Items]
Revenue	28,838	23,513
Billed | Restaurant/Retail | Restaurant/Retail
Disaggregation of Revenue [Line Items]
Revenue	28,838	23,023
Billed | Restaurant/Retail | Grocery
Disaggregation of Revenue [Line Items]
Revenue		490
Billed | Restaurant/Retail | Mission Systems
Disaggregation of Revenue [Line Items]
Revenue	0	0
Billed | Restaurant/Retail | ISR Solutions
Disaggregation of Revenue [Line Items]
Revenue	0	0
Advanced billings | Restaurant/Retail
Disaggregation of Revenue [Line Items]
Revenue	8,571	6,047
Advanced billings | Restaurant/Retail | Restaurant/Retail
Disaggregation of Revenue [Line Items]
Revenue	8,571	5,103
Advanced billings | Restaurant/Retail | Grocery
Disaggregation of Revenue [Line Items]
Revenue		944
Advanced billings | Restaurant/Retail | Mission Systems
Disaggregation of Revenue [Line Items]
Revenue	0	0
Advanced billings | Restaurant/Retail | ISR Solutions
Disaggregation of Revenue [Line Items]
Revenue	0	0
Advanced billings | Government
Disaggregation of Revenue [Line Items]
Revenue	17,323	15,122
Advanced billings | Government | Restaurant/Retail
Disaggregation of Revenue [Line Items]
Revenue	0	0
Advanced billings | Government | Grocery
Disaggregation of Revenue [Line Items]
Revenue		0
Advanced billings | Government | Mission Systems
Disaggregation of Revenue [Line Items]
Revenue	8,448	8,546
Advanced billings | Government | ISR Solutions
Disaggregation of Revenue [Line Items]
Revenue	$ 8,875	$ 6,576