Note 3 - Fair Value Measurements (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2015

Dec. 31, 2014

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

	Fair Value of Assets and Liabilities as of September 30, 2015
	Level 1		Level 2		Level 3		Total
Assets
Money market funds	$	6,000	$	-	$	-	$	6,000
Total assets	$	6,000	$	-	$	-	$	6,000
Liabilities
	$	-	$	-			$	-
Total liabilities	$	-	$	-	$	-	$	-

	Assets and Liabilities at Fair Value as of December 31, 2013
	Quoted prices in active markets for identical assets		Significant other observable inputs		Significant unobservable inputs
	Level 1		Level 2		Level 3		Total
Assets
	$	-	$	-	$	-	$	-
Total assets	$	-	$	-	$	-	$	-
Liabilities
Preferred stock warrant liabilities	$	-	$	-	$	624	$	624
Total liabilities	$	-	$	-	$	624	$	624

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

Fair value as of December 31, 2012	$	686
Change in fair value recorded in other income (expense), net		(62	)
Fair value as of December 31, 2013		624
Change in fair value recorded in other income (expense), net		(52	)
Extinguishment of warrant liabilities pursuant to the Merger Agreement		(572	)
Fair value as of December 31, 2014	$	-

Fair Value Inputs, Liabilities, Quantitative Information [Table Text Block]

	Fair Value as of
	December 31, 2013		Valuation	Unobservable	Range
	(in thousands)		Techniques	Input	(Weighted-Average)
Preferred stock warrant liabilities	$	624	Black-Scholes	Preferred series
			option pricing	prices	$0.04	-	$0.44	($0.06)
			model
				Volatility	70.6%	-	84.2%	(76%)