Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Numerator:
Net income available to common stockholders	$ (2,925)	$ (1,325)	$ 27	$ (528)	$ (1,076)	$ (1,680)	$ (1,892)	$ (472)	$ (4,751)	$ (5,120)	$ 1,926
Denominator:
Common shares	91,175	90,774	89,987	89,434	88,888	88,289	88,557	88,233	90,340	88,477	89,071
Denominator for basic calculation	91,175	90,774	89,987	89,434	88,888	88,289	88,557	88,233	90,340	88,477	89,071
Employee stock options									0	0	2,088
Employee stock purchase rights									0	0	493
Denominator for diluted calculation	91,175	90,774	93,447	89,434	88,888	88,289	88,557	88,233	90,340	88,477	91,652
Net loss per share:
Basic	$ (0.03)	$ (0.01)	$ 0.00	$ (0.01)	$ (0.01)	$ (0.02)	$ (0.02)	$ (0.01)	$ (0.05)	$ (0.06)	$ 0.02
Diluted	$ (0.03)	$ (0.01)	$ 0.00	$ (0.01)	$ (0.01)	$ (0.02)	$ (0.02)	$ (0.01)	$ (0.05)	$ (0.06)	$ 0.02