Certain Financial Statement Information (Details 14) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Schedule of Interest Income, Net
Interest income	$ 685	$ 807	$ 1,915	$ 2,896
Net realized gain on short-term investments	207	21	1,401	682
Interest income, net	$ 892	$ 828	$ 3,316	$ 3,578