Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Accrued research and development expenses	$ 596	$ 318
Accrued employee bonus compensation	203	730
Employee withholdings	6	22
Other accrued expenses	252	198
Total accrued expenses	$ 1,057	$ 1,268