Note 4 - Fair Value Measurement and Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Values on a Recurring Basis (Details) - Fair Value, Measurements, Recurring [Member] $ in Thousands	Jun. 30, 2018 USD ($)
Liabilities:
Warrant liability	$ 185
Total liabilities	185
Fair Value, Inputs, Level 1 [Member]
Liabilities:
Warrant liability
Total liabilities
Fair Value, Inputs, Level 2 [Member]
Liabilities:
Warrant liability
Total liabilities
Fair Value, Inputs, Level 3 [Member]
Liabilities:
Warrant liability	185
Total liabilities	$ 185