Note 4 - Summary of Significant Accounting Policies - Valuation Assumptions (Details) - Fair Value, Inputs, Level 3 [Member] - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Series 2023 PIK Note Derivative Liability [Member]
Market price and estimated fair value of stock (in dollars per share)	$ 0.15	$ 0.28
Exercise price (in dollars per share)	$ 1.28	$ 1.36
Term (years)	6 years 302 days	7 years 211 days
Expected volatility	89.00%	72.90%
Risk-free interest rate	1.40%	2.12%
Series A PIK Note Derivative Liability [Member]
Market price and estimated fair value of stock (in dollars per share)	$ 0.15	$ 0.28
Exercise price (in dollars per share)	$ 0.83	$ 0.92
Term (years)	6 years 302 days	7 years 211 days
Expected volatility	89.00%	72.90%
Risk-free interest rate	1.40%	2.12%