Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Jan. 01, 2019	Dec. 31, 2018
Operating Lease, Liability, Current	$ 135,000
Operating Lease, Weighted Average Discount Rate, Percent	8.00%
Operating Lease, Right-of-Use Asset	$ 135,000
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect, Total	(2,608,000)	$ 4,186,000
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