Fair Value Measurements (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Sep. 30, 2010	Dec. 31, 2011	Dec. 31, 2010
Investment Owned, at Cost		$ 133	$ 143
Volatilities used in valuations Range		16% to 47%
Discount factors used in valuations Range		0.295% to 0.676%
Asset Impairment Charges	146
Fair Value Assets Measured On Nonrecurring Basis Estimated Fair Value Of Aircraft	97
Short-term Investments [Member]
Investments, Fair Value Disclosure		958	718
Short-term Investments [Member] \| Fair Value, Inputs, Level 3 [Member]
Investments, Fair Value Disclosure		0	0
Long Term Investments [Member]
Investments, Fair Value Disclosure		188	144
Long Term Investments [Member] \| Fair Value, Inputs, Level 3 [Member]
Investments, Fair Value Disclosure		$ 109	$ 119

The charge against earnings resulting from the aggregate write down of all assets from their carrying value to their fair value.

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This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents investment securities as of the balance sheet date which may include marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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