Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounts Payable and Accrued Liabilities, Current [Abstract]
Payroll and other employee benefits	$ 465	$ 1,593
Accrued vacation	294	533
Accrued legal expenses - patent	5,479	6,564
Foreign taxes payable	15	3,150
Accrued consulting and other professional fees	1,364	1,967
Other accrued liabilities	339	476
Accounts payable and accrued expenses	$ 7,956	$ 14,283