Certain Financial Statement Information Short-Term Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Mar. 31, 2015		Jun. 30, 2014	[2]	Mar. 31, 2014	[2]
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Available-for-sale Securities, Amortized Cost	$ 76,314	$ 73,403
Available-for-sale Securities, Gross Unrealized Gains	425	2,020
Available-for-sale Securities, Gross Unrealized Losses	(123)	(65)
Available-for-sale Securities, Estimated Fair Value	76,616	75,358
Cash and cash equivalents	44,290	36,495	[1]	$ 62,267		$ 71,539
Short-term investments available-for-sale	32,326	38,863	[1]
Cash, Cash equivalents and Short-term investments, Estimated Fair Value	76,616	75,358
Cash
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Cash and Cash equivalents, Estimated Fair Value	35,209	33,936
Cash equivalents
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Cash and Cash equivalents, Estimated Fair Value	9,081	2,559
U.S Treasury securities and agency bonds
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Available-for-sale Securities, Amortized Cost	985	1,230
Available-for-sale Securities, Gross Unrealized Gains	0	0
Available-for-sale Securities, Gross Unrealized Losses	0	0
Available-for-sale Securities, Estimated Fair Value	985	1,230
Corporate bonds
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Available-for-sale Securities, Amortized Cost	10,918	10,772
Available-for-sale Securities, Gross Unrealized Gains	17	28
Available-for-sale Securities, Gross Unrealized Losses	(13)	(6)
Available-for-sale Securities, Estimated Fair Value	10,922	10,794
Mortgage-backed securities
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Available-for-sale Securities, Amortized Cost	0	0
Available-for-sale Securities, Gross Unrealized Gains	6	15
Available-for-sale Securities, Gross Unrealized Losses	0	0
Available-for-sale Securities, Estimated Fair Value	6	15
Municipal bonds
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Available-for-sale Securities, Amortized Cost	267	0
Available-for-sale Securities, Gross Unrealized Gains	0	0
Available-for-sale Securities, Gross Unrealized Losses	0	0
Available-for-sale Securities, Estimated Fair Value	267	0
Mutual Funds
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Available-for-sale Securities, Amortized Cost	19,849	24,895
Available-for-sale Securities, Gross Unrealized Gains	391	1,955
Available-for-sale Securities, Gross Unrealized Losses	(110)	(59)
Available-for-sale Securities, Estimated Fair Value	20,130	26,791
Preferred stock
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Available-for-sale Securities, Amortized Cost	5	11
Available-for-sale Securities, Gross Unrealized Gains	11	22
Available-for-sale Securities, Gross Unrealized Losses	0	0
Available-for-sale Securities, Estimated Fair Value	$ 16	$ 33

[1] The Condensed Consolidated Balance Sheet as of March 31, 2015 has been derived from the audited Consolidated Financial Statements at that date but does not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements.

[2] The Statement of Cash Flows for the three months ended June 30, 2014 reflects an immaterial revision to correct outstanding payables related to purchases of property and equipment previously included in net cash used for investing activities to net cash used for operating activities. As a result, net cash used for operating activities increased by $0.3 million and net cash used for investing activities decreased by the corresponding amount.