Segment and Geographic Information - Segment Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Total revenues	$ 16,083	$ 4,000	$ 46,028	$ 11,529
Software development
Segment Reporting Information [Line Items]
Total revenues	190	517	537	1,730
Monthly Service
Segment Reporting Information [Line Items]
Total revenues	$ 15,893	$ 3,483	$ 45,491	$ 9,799