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Note 7 - Secured Notes to Related Party (Details Textual) - USD ($)				1 Months Ended	3 Months Ended
	Aug. 05, 2016	Aug. 02, 2016	Jul. 29, 2011	Apr. 30, 2011	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Convertible Debt Issuable in Connection with Private Placement				$ 4,500,000
Proceeds from Convertible Debt				$ 4,300,000
Amortization of Debt Discount (Premium)					$ 210,000	$ 185,000
Convertible Notes Payable, Related Parties, Current					3,894,000		$ 3,684,000
Convertible Debt [Member]
Debt Instrument, Interest Rate, Stated Percentage				6.00%
Debt Instrument Conversion Ratio Multiple of Principal				$ 1,000
Beneficial Ownership after Conversion				9.99%
Notice Period Associated with Beneficial Ownership Percentage Limitation Convertible Notes				61 days
Common Shares Registered for Resale in Connection with Convertible Notes			3,500,000
Debt Instrument, Term				10 years
Paid-in-Kind Interest					100,000
Debt Instrument, Increase (Decrease), Other, Net					100,000
Interest Expense, Debt, Excluding Amortization					100,000	100,000
Amortization of Debt Discount (Premium)					200,000	200,000
Debt Instrument, Face Amount					6,500,000
Debt Instrument, Unamortized Discount, Total					$ 2,600,000
Debt Instrument, Convertible, Number Shares of Equity Insturments					8,100,000
Convertible Debt [Member] \| Common Stock [Member]
Debt Instrument Conversion Ratio Shares				1,250
Term Loan [Member] \| Tang Capital [Member]
Debt Instrument, Interest Rate, Stated Percentage		8.00%
Debt Instrument, Term		2 years
Debt Agreement, Maximum Borrowing Capacity		$ 100,000,000
Proceeds from Issuance of Long-term Debt, Total	$ 50,000,000
Proceeds from Issuance of Long-term Debt, Subject to Achievement of Corporate Milestone		50,000,000
Debt Instrument, Fee Amount		$ 0
Debt Instrument, Number of Warrants		0
Debt Instrument, Convertible, Beneficial Conversion Feature		$ 0
Interest Expense, Total					$ 500,000	$ 1,000,000
Notes Payable, Related Parties, Noncurrent					$ 25,000,000