Revenue - Disaggregated Revenue by Geography (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Total Revenues	$ 6,452	$ 16,070	$ 25,555	$ 40,708
United States
Disaggregation of Revenue [Line Items]
Total Revenues	5,727	11,629	22,104	30,701
South America
Disaggregation of Revenue [Line Items]
Total Revenues	282	278	474	904
Europe
Disaggregation of Revenue [Line Items]
Total Revenues	283	1,907	1,568	4,935
Asia
Disaggregation of Revenue [Line Items]
Total Revenues	160	2,256	1,409	4,168
Total Foreign Revenues
Disaggregation of Revenue [Line Items]
Total Revenues	$ 725	$ 4,441	$ 3,451	$ 10,007