Selected Balance Sheet Information (Details 2) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Accrued Expenses [Line Items]
Accrued clinical consulting services	$ 1,812	$ 2,211
Accrued vendor payments	280	400
Accrued manufacturing expense	38	14
Other accrued expenses	4	2
Total	$ 2,134	$ 2,627