Net Income (Loss) Per Share - Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net income (loss) used in calculating net income (loss) per share, basic	$ (1,390)	$ (2,257)	$ 5,997	$ (26,065)
Net income (loss) used in calculating net income (loss) per share, diluted	$ (1,390)	$ (2,257)	$ 5,997	$ (26,065)
Denominator:
Weighted average shares of common stock outstanding used in computing net income (loss) per share, basic (in shares)	17,945	17,603	17,860	16,368
Dilutive effect of incremental shares and share equivalents:
Weighted average shares of common stock outstanding used in computing net income (loss) per share, diluted (in shares)	17,945	17,603	18,327	16,368
Net income (loss) per share:
Net income (loss) per share, basic (USD per share)	$ (0.08)	$ (0.13)	$ 0.34	$ (1.59)
Net income (loss) per share, diluted (USD per share)	$ (0.08)	$ (0.13)	$ 0.33	$ (1.59)
Options
Dilutive effect of incremental shares and share equivalents:
Dilutive effect of share-based payment arrangements (in shares)	0	0	70	0
RSUs
Dilutive effect of incremental shares and share equivalents:
Dilutive effect of share-based payment arrangements (in shares)	0	0	297	0
PSUs
Dilutive effect of incremental shares and share equivalents:
Dilutive effect of share-based payment arrangements (in shares)	0	0	81	0
ESPP
Dilutive effect of incremental shares and share equivalents:
Dilutive effect of share-based payment arrangements (in shares)	0	0	19	0