Note 7 - Fair Value Measurements - Fair Value of Liabilities on a Recurring Basis (Details) - Fair Value, Recurring [Member] $ in Thousands	Jun. 30, 2018 USD ($)
Warrant derivative liabilities	$ (1,528)
Total warrant derivative liabilities	(1,528)
Fair Value, Inputs, Level 1 [Member]
Warrant derivative liabilities
Total warrant derivative liabilities
Fair Value, Inputs, Level 2 [Member]
Warrant derivative liabilities
Total warrant derivative liabilities
Fair Value, Inputs, Level 3 [Member]
Warrant derivative liabilities	(1,528)
Total warrant derivative liabilities	$ (1,528)