Revenue Recognition - Schedule of Disaggregated Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue	$ 54,467	$ 54,732
Service
Disaggregation of Revenue [Line Items]
Revenue	18,028	18,775
Product
Disaggregation of Revenue [Line Items]
Revenue	18,556	18,634
Restaurant and Retail
Disaggregation of Revenue [Line Items]
Revenue	36,584	37,409
Government Segment
Disaggregation of Revenue [Line Items]
Revenue	17,883	17,323
Point in Time | Restaurant and Retail
Disaggregation of Revenue [Line Items]
Revenue	21,490	23,641
Point in Time | Restaurant and Retail | Hardware
Disaggregation of Revenue [Line Items]
Revenue	17,835	18,137
Point in Time | Restaurant and Retail | Software
Disaggregation of Revenue [Line Items]
Revenue	243	562
Point in Time | Restaurant and Retail | Service
Disaggregation of Revenue [Line Items]
Revenue	3,412	4,942
Point in Time | Restaurant and Retail | Mission Systems
Disaggregation of Revenue [Line Items]
Revenue	0	0
Point in Time | Restaurant and Retail | ISR Solutions
Disaggregation of Revenue [Line Items]
Revenue	0	0
Point in Time | Restaurant and Retail | Product
Disaggregation of Revenue [Line Items]
Revenue	0	0
Over Time | Restaurant and Retail
Disaggregation of Revenue [Line Items]
Revenue	15,094	13,768
Over Time | Restaurant and Retail | Hardware
Disaggregation of Revenue [Line Items]
Revenue	0	0
Over Time | Restaurant and Retail | Software
Disaggregation of Revenue [Line Items]
Revenue	7,633	6,382
Over Time | Restaurant and Retail | Service
Disaggregation of Revenue [Line Items]
Revenue	7,461	7,386
Over Time | Restaurant and Retail | Mission Systems
Disaggregation of Revenue [Line Items]
Revenue	0	0
Over Time | Restaurant and Retail | ISR Solutions
Disaggregation of Revenue [Line Items]
Revenue	0	0
Over Time | Restaurant and Retail | Product
Disaggregation of Revenue [Line Items]
Revenue	0	0
Over Time | Government Segment
Disaggregation of Revenue [Line Items]
Revenue	17,883	17,323
Over Time | Government Segment | Hardware
Disaggregation of Revenue [Line Items]
Revenue	0	0
Over Time | Government Segment | Software
Disaggregation of Revenue [Line Items]
Revenue	0	0
Over Time | Government Segment | Service
Disaggregation of Revenue [Line Items]
Revenue	0	0
Over Time | Government Segment | Mission Systems
Disaggregation of Revenue [Line Items]
Revenue	9,547	8,448
Over Time | Government Segment | ISR Solutions
Disaggregation of Revenue [Line Items]
Revenue	8,131	8,772
Over Time | Government Segment | Product
Disaggregation of Revenue [Line Items]
Revenue	$ 205	$ 103