Revenue Recognition - Schedule of Disaggregated Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 45,691	$ 44,247	$ 100,423	$ 88,929
Restaurant/Retail
Disaggregation of Revenue [Line Items]
Revenue	27,633	28,262	65,042	57,822
Government
Disaggregation of Revenue [Line Items]
Revenue	18,058	15,985	35,381	31,107
Billed | Restaurant/Retail
Disaggregation of Revenue [Line Items]
Revenue	19,820	21,786	47,635	44,612
Billed | Restaurant/Retail | Restaurant/Retail
Disaggregation of Revenue [Line Items]
Revenue	19,820	21,503	47,635	43,880
Billed | Restaurant/Retail | Grocery
Disaggregation of Revenue [Line Items]
Revenue		283		732
Billed | Restaurant/Retail | Mission Systems
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Billed | Restaurant/Retail | ISR Solutions
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Advanced billings | Restaurant/Retail
Disaggregation of Revenue [Line Items]
Revenue	7,813	6,476	17,407	13,210
Advanced billings | Restaurant/Retail | Restaurant/Retail
Disaggregation of Revenue [Line Items]
Revenue	7,813	5,829	17,407	11,579
Advanced billings | Restaurant/Retail | Grocery
Disaggregation of Revenue [Line Items]
Revenue		647		1,631
Advanced billings | Restaurant/Retail | Mission Systems
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Advanced billings | Restaurant/Retail | ISR Solutions
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Advanced billings | Government
Disaggregation of Revenue [Line Items]
Revenue	18,058	15,985	35,381	31,107
Advanced billings | Government | Restaurant/Retail
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Advanced billings | Government | Grocery
Disaggregation of Revenue [Line Items]
Revenue		0		0
Advanced billings | Government | Mission Systems
Disaggregation of Revenue [Line Items]
Revenue	8,087	8,192	16,535	16,738
Advanced billings | Government | ISR Solutions
Disaggregation of Revenue [Line Items]
Revenue	$ 9,971	$ 7,793	$ 18,846	$ 14,369