Net Income Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net Income Per Share Details
Net income available to common stockholders	$ 1,741	$ 832	$ 10,358	$ 2,779
Common shares	71,261	63,710	70,989	62,989
Denominator for basic calculation	71,261	63,710	70,989	62,989
Employee stock options	2,975	3,622	2,896	3,443
Stock purchase rights	322	427	325	401
Denominator for diluted calculation	74,558	67,759	74,210	66,833
Net income per share
Basic	$ 0.02	$ 0.01	$ 0.15	$ 0.04
Diluted	$ 0.02	$ 0.01	$ 0.14	$ 0.04