Marketable Investments (Details 4) (USD $)	Sep. 30, 2012
Amortized Cost
Due in less than one year, Amortized Cost	$ 240,032,000
Due in one to two years, Amortized Cost	248,355,000
Total Amortized Cost	488,387,000
Fair Value
Due in less than one year, Fair Value	240,342,000
Due in one to two years, Fair Value	248,559,000
Total Fair Value	488,901,000
Equity Investments
Available-for-sale investment in common stock, less than a certain percentage	1.00%
Investments in equity of privately-held corporations	$ 8,000,000

This element represents the aggregate carrying amount of all cost-method investments held by the Company. Generally, such investments do not have readily determinable fair values and are not required to be accounted for by the equity method. The carrying amount of such securities equates to cost, adjusted for other-than-temporary impairment. The cost method and lower-of-cost or market, an adaptation of the cost method, is generally followed for most investments in noncontrolled corporations, in some corporate joint ventures, and to a lesser extent in unconsolidated subsidiaries, particularly foreign.

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This item represents the total of all debt securities grouped by maturity dates, at fair value, which are categorized as held-to-maturity.

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Carrying amount of debt securities accounted for as held-to-maturity, net of adjustments including, but not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized, and fair value hedge accounting adjustments.

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The entity owns less than this percentage of common stock of an available-for-sale investee.

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