Summary of Significant Accounting Policies - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 10,474	$ 21,684	$ 34,955	$ 42,462
Europe
Disaggregation of Revenue [Line Items]
Revenue	6,153	9,280	15,932	18,687
Latin America
Disaggregation of Revenue [Line Items]
Revenue	1,366	6,017	8,508	12,184
Asia-Pacific/Middle East
Disaggregation of Revenue [Line Items]
Revenue	2,880	6,276	10,350	11,222
Other
Disaggregation of Revenue [Line Items]
Revenue	$ 75	$ 111	$ 165	$ 369