Certain Financial Statement Information Short-Term Investments (Details) (USD $)	9 Months Ended
	Dec. 31, 2013		Dec. 31, 2012	Mar. 31, 2013		Mar. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Cost method investment, ownership percentage (less than)	20.00%
Investments in non-marketable equity investments, cost method	$ 0		$ 500,000
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Cash, Cash equivalents and Short-term investments, Amortized Cost	71,654,000			77,442,000
Available for sale Securities Gross Unrealized Gains	3,503,000			8,082,000
Available For Sale Securities Gross Unrealized Losses	(873,000)			(48,000)
Cash, Cash equivalents and Short-term investments, Estimated Fair Value	74,284,000			85,476,000
Cash and cash equivalents	23,630,000		15,683,000	19,065,000	[1]	28,065,000
Short-term investments available-for-sale	50,654,000			66,411,000	[1]
Cash [Member]
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Cash, Cash equivalents and Short-term investments, Amortized Cost	19,716,000			8,529,000
Available for sale Securities Gross Unrealized Gains	0			0
Available For Sale Securities Gross Unrealized Losses	0			0
Cash and Cash equivalents, Estimated Fair Value	19,716,000			8,529,000
Cash equivalents [Member]
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Cash, Cash equivalents and Short-term investments, Amortized Cost	3,914,000			10,536,000
Available for sale Securities Gross Unrealized Gains	0			0
Available For Sale Securities Gross Unrealized Losses	0			0
Cash and Cash equivalents, Estimated Fair Value	3,914,000			10,536,000
U.S Treasury securities and agency bonds [Member]
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Cash, Cash equivalents and Short-term investments, Amortized Cost	11,747,000			12,363,000
Available for sale Securities Gross Unrealized Gains	8,000			10,000
Available For Sale Securities Gross Unrealized Losses	(4,000)			0
Cash, Cash equivalents and Short-term investments, Estimated Fair Value	11,751,000			12,373,000
Corporate bonds [Member]
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Cash, Cash equivalents and Short-term investments, Amortized Cost	15,482,000			15,567,000
Available for sale Securities Gross Unrealized Gains	56,000			63,000
Available For Sale Securities Gross Unrealized Losses	(4,000)			(2,000)
Cash, Cash equivalents and Short-term investments, Estimated Fair Value	15,534,000			15,628,000
Mortgage-backed and asset-backed securities [Member]
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Cash, Cash equivalents and Short-term investments, Amortized Cost	4,015,000			3,655,000
Available for sale Securities Gross Unrealized Gains	300,000			355,000
Available For Sale Securities Gross Unrealized Losses	(47,000)			(7,000)
Cash, Cash equivalents and Short-term investments, Estimated Fair Value	4,268,000	[2]		4,003,000	[2]
Closed-end bond funds [Member]
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Cash, Cash equivalents and Short-term investments, Amortized Cost	14,374,000			21,914,000
Available for sale Securities Gross Unrealized Gains	2,261,000			5,340,000
Available For Sale Securities Gross Unrealized Losses	(818,000)			(39,000)
Cash, Cash equivalents and Short-term investments, Estimated Fair Value	15,817,000			27,215,000
Preferred stock [Member]
Schedule of cash, cash equivalents and available-for-sale investments by type of instruments
Cash, Cash equivalents and Short-term investments, Amortized Cost	2,406,000			4,878,000
Available for sale Securities Gross Unrealized Gains	878,000			2,314,000
Available For Sale Securities Gross Unrealized Losses	0			0
Cash, Cash equivalents and Short-term investments, Estimated Fair Value	3,284,000			7,192,000
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	$ 1,100,000	[2]		$ 1,400,000	[2]

[1] Amounts have been derived from the March 31, 2013 audited consolidated financial statements.

[2] At December 31, 2013 and March 31, 2013, approximately $1.1 million and $1.4 million of the estimated fair value presented were mortgage-backed securities, respectively.