Note 7 - Accrued Expenses - Summary of Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accrued payroll and related costs	$ 2,871	$ 2,400
Accrued contract manufacturing costs	2,516	666
Accrued clinical trial costs	2,318	2,570
Accrued consulting and service fee expenses	1,229	1,860
Accrued legal and professional fees	1,191	1,022
Other	408	1,037
Accrued expenses	$ 10,533	$ 9,555