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Note 8 - Secured Notes to Related Party (Details Textual) - USD ($)				1 Months Ended			12 Months Ended
	Aug. 05, 2016	Aug. 02, 2016	Jul. 29, 2011	Aug. 31, 2018	Aug. 31, 2016	Apr. 30, 2011	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Convertible Debt Issuable in Connection with Private Placement						$ 4,500,000
Proceeds from Convertible Debt						$ 4,300,000
Amortization of Debt Discount (Premium)							$ 890,000	$ 773,000	$ 689,000
Convertible Notes Payable, Related Parties, Current							4,574,000	3,684,000
Interest Expense, Total							2,672,000	3,937,000	2,664,000
Repayments of Long-term Debt, Total							25,000,000	25,000,000
Interest Paid, Excluding Capitalized Interest, Operating Activities							1,183,000	2,789,000	1,622,000
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								400,000
Debt Instrument, Increase (Decrease), Other, Net								400,000
Amortization of Debt Discount (Premium)							900,000	800,000	700,000
Debt Instrument, Face Amount							6,800,000
Debt Instrument, Unamortized Discount, Total							$ 2,200,000
Debt Instrument, Convertible, Number Shares of Equity Insturments							8,500,000
Interest Expense, Debt, Excluding Amortization							$ 400,000	400,000	$ 400,000
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							1,200,000	$ 2,800,000
Repayments of Long-term Debt, Total				$ 25,000,000
Interest Paid, Excluding Capitalized Interest, Operating Activities				$ 200,000
Long-term Debt, Total							$ 0