Net Income Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Net Income Per Share Details
Net income available to common stockholders	$ 2,139	$ 8,617
Common shares	72,510	70,717
Denominator for basic calculation	72,510	70,717
Employee stock options	2,911	2,759
Stock purchase rights	335	309
Employee stock purchase plan	0	325
Denominator for diluted calculation	75,756	74,110
Net income per share
Basic	$ 0.03	$ 0.12
Diluted	$ 0.03	$ 0.12