Cash, Cash Equivalents and Short-Term Investments (Details Textual) (USD $)	Jun. 30, 2012	Dec. 31, 2011
Cash, Cash Equivalents and Short Term Investments (Additional Textual) [Abstract]
Amortized Cost of investment with loss positions	$ 5,900,000	$ 12,800,000
Fair value of investments with loss positions	5,900,000	12,800,000
Variable Rate Demand Note Maturity Year	2037
Maturity on Demand [Member]
Cash, Cash Equivalents and Short-Term Investments (Textual) [Abstract]
Securities amortized cost Due in one year or less	1,500,000	1,900,000
Securities fair value Due in one year or less	$ 1,500,000	$ 1,900,000

This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

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This item represents debt securities, at cost, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments, as defined), and fair value hedge accounting adjustments, if any, which are expected to mature within one year of the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

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- Definition

This item represents the fair value of debt securities which are expected to mature within one year of the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

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