Certain Financial Statement Information Short-Term Investments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Jun. 30, 2014		Mar. 31, 2014		Jun. 30, 2013	Mar. 31, 2013
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Available-for-sale Securities, Amortized Cost	$ 94,913		$ 103,548
Available-for-sale Securities, Gross Unrealized Gain	3,802		3,455
Available-for-sale Securities, Gross Unrealized Loss	105		420
Available-for-sale Securities, Estimated Fair Value	98,610		106,583
Cash and cash equivalents	62,267		71,539		39,673	19,065
Short-term investments available-for-sale	36,343		35,044
Cash, Cash equivalents and Short-term investments, Estimated Fair Value	98,610		106,583
Cash [Member]
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Cash and Cash equivalents, Estimated Fair Value	56,869		65,867
Cash equivalents [Member]
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Cash and Cash equivalents, Estimated Fair Value	5,398		5,672
U.S Treasury securities and agency bonds [Member]
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Available-for-sale Securities, Amortized Cost	2,838		2,838
Available-for-sale Securities, Gross Unrealized Gain	0		0
Available-for-sale Securities, Gross Unrealized Loss	0		0
Available-for-sale Securities, Estimated Fair Value	2,838		2,838
Corporate bonds [Member]
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Available-for-sale Securities, Amortized Cost	11,320		10,599
Available-for-sale Securities, Gross Unrealized Gain	41		30
Available-for-sale Securities, Gross Unrealized Loss	1		2
Available-for-sale Securities, Estimated Fair Value	11,360		10,627
Mortgage-backed and asset-backed securities [Member]
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Available-for-sale Securities, Amortized Cost	1,709		1,793
Available-for-sale Securities, Gross Unrealized Gain	323		297
Available-for-sale Securities, Gross Unrealized Loss	2		16
Available-for-sale Securities, Estimated Fair Value	2,030	[1]	2,074	[1]
Closed-end bond funds [Member]
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Available-for-sale Securities, Amortized Cost	14,373		14,373
Available-for-sale Securities, Gross Unrealized Gain	2,709		2,392
Available-for-sale Securities, Gross Unrealized Loss	102		402
Available-for-sale Securities, Estimated Fair Value	16,980		16,363
Preferred stock [Member]
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Available-for-sale Securities, Amortized Cost	2,406		2,406
Available-for-sale Securities, Gross Unrealized Gain	729		736
Available-for-sale Securities, Gross Unrealized Loss	0		0
Available-for-sale Securities, Estimated Fair Value	3,135		3,142
Mortgage-backed securities [Member]
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Cash, Cash equivalents and Short-term investments, Estimated Fair Value	$ 1,100	[1]	$ 1,100	[1]

[1] At June 30, 2014 and March 31, 2014, approximately $1.1 million of the estimated fair value presented were mortgage-backed securities.