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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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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Amount of held-to-maturity debt securities at fair value maturing in the next fiscal year following the latest fiscal year.

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The sum of the realized and unrealized net gain (loss) on trading securities during the period.

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

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Marketable Investments (Details 4) (USD $)	12 Months Ended
Marketable Investments (Details 4) (USD $)	Dec. 31, 2010	Dec. 31, 2012	Dec. 31, 2011
Amortized Cost
Due in less than one year, Amortized Cost		$ 325,175,000
Due in one to two years, Amortized Cost		305,253,000
Total Amortized Cost		630,428,000
Fair Value
Due in less than one year, Fair Value		325,392,000
Due in one to two years, Fair Value		305,306,000
Total Fair Value		630,698,000
Trading Investments
Trading gains	6,900,000
Equity Investments
Available-for-sale investment in common stock, less than a certain percentage		1.00%	1.00%
Investments in equity of privately-held corporations		$ 8,000,000