Note 7 - Accrued Expenses - Summary of Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Accrued contract manufacturing costs	$ 2,946	$ 2,516
Accrued clinical trial costs	1,817	2,318
Accrued payroll and related costs	1,411	2,871
Accrued consulting and service fee expenses	847	1,229
Accrued legal and professional fees	1,529	1,191
Other	954	408
Accrued expenses	$ 9,504	$ 10,533