Revenue - Disaggregated Revenue by Geography (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Total Revenues	$ 10,155	$ 12,791
United States
Disaggregation of Revenue [Line Items]
Total Revenues	8,815	10,242
South America
Disaggregation of Revenue [Line Items]
Total Revenues	175	335
Europe
Disaggregation of Revenue [Line Items]
Total Revenues	617	1,454
Asia
Disaggregation of Revenue [Line Items]
Total Revenues	548	760
Total Foreign Revenues
Disaggregation of Revenue [Line Items]
Total Revenues	$ 1,340	$ 2,549