Cash, Cash Equivalents, and Available-For-Sale Investments (Details Textuals)	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010
Cash Cash Equivalents and Available For Sale Investments (Textuals) [Abstract]
Realized gains and losses from sales of available-for-sale securities	less than $0.1 million	less than $0.1 million
Maturity term for debt securities investment	two years or less

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