Cash, Cash Equivalents, and Available-For-Sale Investments (Details 2) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Portfolio of available-for-sale investments
Less than one year	$ 296,720	$ 213,386
Greater than one year but less than two years	44,245	186,238
Total available-for-sale investments	$ 340,965	$ 399,624

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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