Note 6 - Fair Value Measurements - Fair Value of Liabilities on a Recurring Basis (Details) $ in Thousands	Sep. 30, 2017 USD ($)
Warrant liabilities	$ 4,500
Fair Value, Measurements, Recurring [Member]
Warrant liabilities	(6,642)
Total warrant liabilities	(6,642)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Warrant liabilities
Total warrant liabilities
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Warrant liabilities	(4,537)
Total warrant liabilities	(4,537)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Warrant liabilities	(2,105)
Total warrant liabilities	$ (2,105)