Selected Balance Sheet Information - Schedule of accrued expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Selected Balance Sheet Information
Accrued clinical consulting services	$ 684	$ 674
Accrued manufacturing costs	635	83
Accrued vendor payments	456	150
Other accrued expenses	1	12
Total	$ 1,776	$ 919