Certain Financial Statement Information - Short Term Investments Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Mar. 31, 2015
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	$ 75,500	$ 75,358
Cash
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	16,224	33,936
Cash equivalents
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	4,851	2,559
U.S Treasury securities and agency bonds
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	23,853	1,230
Corporate bonds
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	24,567	10,794
Asset-backed securities
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	4,634	15
Municipal bonds
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	1,355	0
Mutual Funds
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	0	26,791
Preferred stock
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	16	33
Recurring
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	75,500	75,358
Recurring | Level 1
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	46,283	64,516
Recurring | Level 2
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	29,217	10,842
Recurring | Level 3
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	0	0
Recurring | Cash
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	16,224	33,936
Recurring | Cash | Level 1
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	16,224	33,936
Recurring | Cash | Level 2
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	0	0
Recurring | Cash | Level 3
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	0	0
Recurring | Cash equivalents
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	4,851	2,559
Recurring | Cash equivalents | Level 1
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	4,851	2,559
Recurring | Cash equivalents | Level 2
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	0	0
Recurring | Cash equivalents | Level 3
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	0	0
Recurring | U.S Treasury securities and agency bonds
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	23,853	1,230
Recurring | U.S Treasury securities and agency bonds | Level 1
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	23,853	1,230
Recurring | U.S Treasury securities and agency bonds | Level 2
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	0	0
Recurring | U.S Treasury securities and agency bonds | Level 3
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	0	0
Recurring | Corporate bonds
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	24,567	10,794
Recurring | Corporate bonds | Level 1
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	0	0
Recurring | Corporate bonds | Level 2
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	24,567	10,794
Recurring | Corporate bonds | Level 3
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	0	0
Recurring | Asset-backed securities
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	4,634	15
Recurring | Asset-backed securities | Level 1
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	0	0
Recurring | Asset-backed securities | Level 2
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	4,634	15
Recurring | Asset-backed securities | Level 3
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	0	0
Recurring | Municipal bonds
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	1,355	0
Recurring | Municipal bonds | Level 1
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	1,355	0
Recurring | Municipal bonds | Level 2
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	0	0
Recurring | Municipal bonds | Level 3
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	0	0
Recurring | Mutual Funds
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	0	26,791
Recurring | Mutual Funds | Level 1
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	0	26,791
Recurring | Mutual Funds | Level 2
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	0	0
Recurring | Mutual Funds | Level 3
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	0	0
Recurring | Preferred stock
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	16	33
Recurring | Preferred stock | Level 1
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	0	0
Recurring | Preferred stock | Level 2
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	16	33
Recurring | Preferred stock | Level 3
Schedule of Cash, Cash Equivalents and Available-For-Sale Investments by Type of Instruments Measured at Fair Value on Recurring Basis
Available-for-sale securities	$ 0	$ 0