Note 9 - Redeemable Convertible Preferred Stock (Tables)

12 Months Ended

Dec. 31, 2014

Redeemable Convertible Preferred Stock [Abstract]

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

	Upon Issuance			Immediately before IPO
Expected term (in years)	1.84	-	3.50		0.001
Expected volatility	63.0%	-	86.0%	63.0%	-	71.0%
Risk-free interest rate	0.44%	-	1.12%	0.35%	-	1.05%
Expected dividend yield		0%			0%

Schedule Of Series D Investors' Rights [Table Text Block]

	Amount
Fair value of tranche right liability upon issuance May 13, 2014	$	6,639
Issuance costs allocated to tranche right liability		(80	)
Adjustment to fair value recorded in other income during 2014		(5,151	)
Reclassified to equity upon exercise on October 21, 2014		(1,408	)
Balance at December 31, 2014	$	-