Asset Impairments, Lease Terminations and Other (Leases) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	3 Months Ended
Jun. 30, 2009	Jun. 30, 2009 Midland Cogeneration Ventures	Dec. 31, 2011 American Airlines Lease
Lease Disclosures [Line Items]
Proceeds from termination of cross-border leases, before tax	$ 1,385
Loss from termination of cross-border leases, before tax	920
Pre-tax gain on sale		33
Pre-tax write down of investment			26
Net of tax write down of investment			$ 16

The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

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