Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Jan. 01, 2019
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect, Total	$ (10,022,000)	$ (2,945,000)
Restricted Cash and Cash Equivalents, Total	22,000	22,000
Accounting Standards Update 2016-02 [Member]
Operating Lease, Liability, Current			$ 200,000
Operating Lease, Weighted Average Discount Rate, Percent			8.00%
Operating Lease, Right-of-Use Asset			$ 200,000
Accounting Standards Update 2016-18 [Member]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect, Total	$ 22,000	$ 22,000