Note 8 - Net Loss Per Share Attributable to Common Stockholders (Tables)

9 Months Ended

Sep. 30, 2016

Notes Tables

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]

	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2015		2016		2015
Outstanding stock options		2,169,617		1,800,262		2,169,617		1,800,262
Outstanding ESPP shares		10,913		1,097		10,913		1,097
		2,180,530		1,801,359		2,180,530		1,801,359