Certain Financial Statement Information (Details 10) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Mar. 31, 2013
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	$ 89,730		$ 85,476
Cash, cash equivalents and available-for-sale investments measured at fair value on recurring basis	89,730		85,476
Level 1 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and available-for-sale investments measured at fair value on recurring basis	69,380		57,625
Level 2 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and available-for-sale investments measured at fair value on recurring basis	20,350		27,851
Level 3 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and available-for-sale investments measured at fair value on recurring basis	0		0
Cash [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash and cash equivalents measured at fair value on a recurring basis	13,140		8,529
Cash [Member] | Level 1 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash and cash equivalents measured at fair value on a recurring basis	13,140		8,529
Cash [Member] | Level 2 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash and cash equivalents measured at fair value on a recurring basis	0		0
Cash [Member] | Level 3 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash and cash equivalents measured at fair value on a recurring basis	0		0
Cash equivalents [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash and cash equivalents measured at fair value on a recurring basis	26,533		10,536
Cash equivalents [Member] | Level 1 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash and cash equivalents measured at fair value on a recurring basis	25,378		9,508
Cash equivalents [Member] | Level 2 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash and cash equivalents measured at fair value on a recurring basis	1,155		1,028
Cash equivalents [Member] | Level 3 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash and cash equivalents measured at fair value on a recurring basis	0		0
U.S Treasury securities and agency bonds [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	12,515		12,373
U.S Treasury securities and agency bonds [Member] | Level 1 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	11,951		12,373
U.S Treasury securities and agency bonds [Member] | Level 2 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	564		0
U.S Treasury securities and agency bonds [Member] | Level 3 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	0		0
Corporate bonds [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	10,829		15,628
Corporate bonds [Member] | Level 1 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	0		0
Corporate bonds [Member] | Level 2 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	10,829		15,628
Corporate bonds [Member] | Level 3 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	0		0
Mortgage-backed and asset-backed securities [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	4,472	[1]	4,003	[1]
Mortgage-backed and asset-backed securities [Member] | Level 1 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	0		0
Mortgage-backed and asset-backed securities [Member] | Level 2 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	4,472		4,003
Mortgage-backed and asset-backed securities [Member] | Level 3 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	0		0
Closed-end bond funds [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	18,911		27,215
Closed-end bond funds [Member] | Level 1 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	18,911		27,215
Closed-end bond funds [Member] | Level 2 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	0		0
Closed-end bond funds [Member] | Level 3 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	0		0
Preferred stock [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	3,330		7,192
Preferred stock [Member] | Level 1 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	0		0
Preferred stock [Member] | Level 2 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	3,330		7,192
Preferred stock [Member] | Level 3 [Member]
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Cash, cash equivalents and short term investments, measured at fair value on a recurring basis	$ 0		$ 0

[1] At June 30, 2013 and March 31, 2013, approximately $1.3 million and $1.4 million of the estimated fair value presented were mortgage-backed securities, respectively.