Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Accrued research and development expenses	$ 561	$ 318
Accrued employee bonus compensation	421	730
Employee withholdings	23	22
Other accrued expenses	324	198
Total accrued expenses	$ 1,329	$ 1,268