Financial Instruments (Net Carrying Value And Estimated Fair Value Of Available-For-Sale Marketable Securities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011
Cost [Member]
Due in one year or less	$ 499
Due after one year through three years	1,956
Due after three years	60
Fair value of available-for-sale marketable securities, cost	2,515
Estimated Fair Value [Member]
Due in one year or less	499
Due after one year through three years	1,955
Due after three years	60
Fair value of available-for-sale marketable securities, cost	$ 2,514

This item represents the total of all debt securities grouped by maturity dates, at cost, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments, as defined), and fair value hedge accounting adjustments, if any, which are classified neither as held-to-maturity nor trading securities.

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This item represents debt securities, at cost, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments, as defined), and fair value hedge accounting adjustments, if any, which are expected to mature within one year of the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

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