Summary of Significant Accounting Policies - Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Inventory, Raw Materials, Net of Reserves	$ 148	$ 148
Inventory, Finished Goods, Net of Reserves	3,103	2,422
Inventory, Net	$ 3,251	$ 2,570