Cash, Cash Equivalents and Short-term Investments (Details Textual) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Cash, Cash Equivalents and Short-term Investments (Textual) [Abstract]
Maturity of fixed-income investments			Three months or less
Maturity of readily marketable securities			more than three months
Realized gain (loss) on available for sale securities	$ 0	$ 0	$ 0	$ 0
Impairment of investments			$ 0

The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

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