Debt Security Investments (Details Textual) (USD $)	6 Months Ended	12 Months Ended
Jun. 30, 2012	Dec. 31, 2011
Debt Security Investments (Textual) [Abstract]
Investments with original maturities, short term	Greater than 90 days
Investments with current maturities, short term	One year or less
Investments with current maturities, long term	Greater than one year
Impairments on the debt security investments	$ 0	$ 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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