Marketable Securities (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012
Money market funds [Member]
Summary of cash equivalents and marketable securities classified as available for sale
Fair value	$ 57,918
Amortized cost	57,918
Gross unrealized gains
Gross unrealized losses
U.S. government bonds and notes [Member]
Summary of cash equivalents and marketable securities classified as available for sale
Fair value	22,052
Amortized cost	22,051
Gross unrealized gains	1
Gross unrealized losses
Total cash equivalents and marketable securities [Member]
Summary of cash equivalents and marketable securities classified as available for sale
Fair value	79,970
Amortized cost	79,969
Gross unrealized gains	1
Gross unrealized losses
Cash [Member]
Summary of cash equivalents and marketable securities classified as available for sale
Fair value	39,817
Amortized cost	39,817
Gross unrealized gains
Gross unrealized losses
Total cash, cash equivalents and marketable securities [Member]
Summary of cash equivalents and marketable securities classified as available for sale
Fair value	119,787
Amortized cost	119,786
Gross unrealized gains	1
Gross unrealized losses

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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This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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