Revenue Recognition - Disaggregated Revenue by Geography (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Total Revenues	$ 56,535	$ 45,166	$ 55,161
United States
Disaggregation of Revenue [Line Items]
Total Revenues	43,887	29,510	42,545
South America
Disaggregation of Revenue [Line Items]
Total Revenues	1,290	2,118	2,934
Europe
Disaggregation of Revenue [Line Items]
Total Revenues	6,260	6,206	4,460
Asia
Disaggregation of Revenue [Line Items]
Total Revenues	5,098	7,332	5,222
Foreign
Disaggregation of Revenue [Line Items]
Total Revenues	$ 12,648	$ 15,656	$ 12,616