Note 4 - Fair Value of Financial Instruments - Reconciliation of All Liabilities Measured At Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Balance at January 1, 2018	$ 67
Issuances
Revaluation loss included in loss on revaluation of financial instruments	3
Settlements	(70)
Balance at December 31, 2018
Total losses included in other income and (expenses) attributable to liabilities still held as of December 31, 2018
Convertible Preferred Stock Warrant Liability [Member]
Balance at January 1, 2018	67
Issuances
Revaluation loss included in loss on revaluation of financial instruments	3
Settlements	(70)
Balance at December 31, 2018
Total losses included in other income and (expenses) attributable to liabilities still held as of December 31, 2018