Revenue Recognition - Schedule of Performance Obligations (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue recognized included in contract liabilities at beginning of period	$ 3,400	$ 8,100
Current - under one year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations	$ 10,736	$ 10,736	$ 9,645
Performance obligation, percentage	71.00%	71.00%
Current - under one year | Restaurant/Retail
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations	$ 10,657	$ 10,657	9,320
Current - under one year | Government
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations	79	79	325
Non-current - over one year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations	$ 4,343	$ 4,343	4,407
Performance obligations, period	60 months	60 months
Non-current - over one year | Restaurant/Retail
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations	$ 4,343	$ 4,343	4,407
Non-current - over one year | Government
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations	$ 0	$ 0	$ 0