Selected Balance Sheet Information (Details 2) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Accrued Expenses [Line Items]
Accrued clinical consulting services	$ 625	$ 658
Accrued vendor payments	221	193
Accrued manufacturing costs	143	661
Other accrued expenses	11	14
Total	$ 1,000	$ 1,526