Note 17 - Income Taxes (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Tax Expense (Benefit)	$ 0	$ 0
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	2,800,000	2,700,000
Unrecognized Tax Benefits that Would Not Impact Effective Tax Rate	398,000	344,000
Deferred Tax Liabilities, Net	0	$ 0
Liability for Uncertainty in Income Taxes, Current	0
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards	48,000,000
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	1,300,000
State and Local Jurisdiction [Member]
Operating Loss Carryforwards	40,800,000
State and Local Jurisdiction [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	$ 1,100,000