Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($)	Jun. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Operating Lease, Liability, Total	$ 781,000
Operating Lease, Liability, Current	565,000
Operating Lease, Right-of-Use Asset	565,000
Deferred Rent Credit, Current			111,000
Retained Earnings (Accumulated Deficit), Ending Balance	$ (104,992,000)		$ (97,989,000)
Accounting Standards Update 2016-02 [Member]
Operating Lease, Liability, Total		$ 1,229,000
Operating Lease, Liability, Current		783,000
Operating Lease, Right-of-Use Asset		953,000
Deferred Rent Credit		(249,000)
Deferred Rent Credit, Current		(111,000)
Retained Earnings (Accumulated Deficit), Ending Balance		$ (27,000)