Accrued Expenses and Other Short Term Liabilities (Short-term Accrued Expenses) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accrued Expenses and Other Short Term Liabilities [Abstract]
Commission payable	$ 2,395	$ 2,395
Compensation and benefits	758	954
Severance	1,122	1,744
Royalty arrangements		2,502
Other	4,302	4,555
Total accrued expenses	$ 8,577	$ 12,150