Segment Reporting and Geographic Information - Schedule of Revenue from External Customers by Products and Services (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total revenue	$ 120,558	$ 62,935	$ 61,511	$ 60,892	$ 62,780	$ 60,432	$ 77,476	$ 73,096	$ 305,896	$ 273,784	$ 255,098
Sales [Member] | Product [Member]
Segment Reporting Information [Line Items]
Concentration risk, percentage									100.00%	100.00%	100.00%
Systems and Software [Member]
Segment Reporting Information [Line Items]
Total revenue									$ 255,723	$ 234,241	$ 216,884
Systems and Software [Member] | Sales [Member] | Product [Member]
Segment Reporting Information [Line Items]
Concentration risk, percentage									84.00%	86.00%	85.00%
Parts Revenue [Member]
Segment Reporting Information [Line Items]
Total revenue									$ 34,892	$ 28,658	$ 27,143
Parts Revenue [Member] | Sales [Member] | Product [Member]
Segment Reporting Information [Line Items]
Concentration risk, percentage									11.00%	10.00%	11.00%
Service Revenue [Member]
Segment Reporting Information [Line Items]
Total revenue									$ 15,281	$ 10,885	$ 11,071
Service Revenue [Member] | Sales [Member] | Product [Member]
Segment Reporting Information [Line Items]
Concentration risk, percentage									5.00%	4.00%	4.00%