Note 10 - Net Loss Per Share - Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Net income (loss)	$ (873)	$ 6,188	$ (4,477)	$ 7,113
Weighted average shares of common stock outstanding used in computing net income (loss) per share, basic (in shares)	13,851	13,973	13,717	13,917
Dilutive effect of incremental shares and share equivalents (in shares)		794		816
Weighted average shares of common stock outstanding used in computing net income (loss) per share, diluted (in shares)	13,851	14,767	13,717	14,733
Net income (loss) per share, basic (in dollars per share)	$ (0.06)	$ 0.44	$ (0.33)	$ 0.51
Net income (loss) per share, diluted (in dollars per share)	$ (0.06)	$ 0.42	$ (0.33)	$ 0.48