Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts Payable and Accrued Liabilities, Current [Abstract]
Payroll and other employee benefits	$ 205	$ 465
Accrued vacation	144	294
Accrued legal expenses - patent	5,974	5,479
Foreign taxes payable	374	15
Accrued consulting and other professional fees	1,241	1,364
Other accrued liabilities	409	339
Accounts payable and accrued expenses	$ 8,347	$ 7,956