Note 7 - Accrued Expenses - Summary of Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Accrued legal and professional fees	$ 3,640	$ 1,305
Accrued payroll and related costs	2,950	2,871
Accrued contract manufacturing costs	2,408	2,516
Accrued clinical trial costs	1,897	2,318
Accrued consulting costs	1,006	862
Other	560	661
Accrued expenses	$ 12,461	$ 10,533