FAIR VALUE MEASUREMENTS (Details) (Recurring basis, USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Mar. 31, 2013
Level 1
Financial Assets
Total cash equivalents and short-term investments	$ 65,188	$ 16,549
Level 1 \| Money market funds
Financial Assets
Total cash equivalents and short-term investments	65,188	16,549
Level 2
Financial Assets
Total cash equivalents and short-term investments	60,412	108,546
Level 2 \| Corporate debentures/bonds
Financial Assets
Total cash equivalents and short-term investments	48,420	75,572
Level 2 \| Commercial paper
Financial Assets
Total cash equivalents and short-term investments	7,992	28,974
Level 2 \| Certificates of deposit
Financial Assets
Total cash equivalents and short-term investments	4,000	4,000
Total fair value
Financial Assets
Total cash equivalents and short-term investments	$ 125,600	$ 125,095

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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