Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details

Segment and Geographic Information - Segment Revenue (Details) $ in Thousands		3 Months Ended		6 Months Ended
	Jun. 30, 2020 segment	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)
Risks and Uncertainties [Abstract]
Number of operating segments \| segment	3
Number of reportable segments \| segment	1
Segment Reporting Information [Line Items]
Total revenue		$ 16,105	$ 16,876	$ 36,160	$ 29,945
Installation and software development
Segment Reporting Information [Line Items]
Total revenue		282	138	418	347
Monthly Service
Segment Reporting Information [Line Items]
Total revenue		$ 15,823	$ 16,738	$ 35,742	$ 29,598