Geographic Information and Concentrations of Risk - Net Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	$ 56,840	$ 48,556
United States and Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	42,350	33,494
South Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	8,238	8,369
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	$ 6,252	$ 6,693