Revenue Recognition - Schedule of Performance Obligations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Dec. 31, 2019
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Support contract timing	12
Revenue, Remaining Performance Obligation [Roll Forward]
Beginning balance	$ 16,000	$ 14,134
Deferral of revenue	8,579	7,023
Recognition of revenue	(8,571)	(6,047)
Changes in customer deposits	(1,741)	1,237
Ending balance	14,267	16,347
Performance obligations	14,267	16,347	$ 14,267	$ 16,000
Restaurant/Retail
Revenue, Remaining Performance Obligation [Roll Forward]
Recognition of revenue	7,200	$ 5,700
Government
Revenue, Remaining Performance Obligation [Roll Forward]
Beginning balance	148,700
Ending balance	136,057
Performance obligations	$ 136,057		136,057	148,700
Funded performance obligations			$ 34,500	$ 32,800
Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Payment period	30 days
Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Payment period	90 days