Geographic Information (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2018
Jun. 30, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]      
Revenue $ 8,595 $ 16,079 $ 18,056
North America      
Revenues from External Customers and Long-Lived Assets [Line Items]      
Revenue   10,165 12,038
International      
Revenues from External Customers and Long-Lived Assets [Line Items]      
Revenue   5,914 6,018
United Kingdom      
Revenues from External Customers and Long-Lived Assets [Line Items]      
Revenue   3,047 3,551
Middle East      
Revenues from External Customers and Long-Lived Assets [Line Items]      
Revenue   $ 2,867 $ 2,467