Acquisitions and Sales of Other Assets (Narrative - Change in PPA) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Significant Acquisitions and Disposals [Line Items]
Current assets	$ 3,204
Property, plant and equipment	23,279
Goodwill	12,467
Other long-term assets, excluding goodwill	9,994
Current liabilities, including current maturities of long-term debt	3,581
Long-term liabilities, preferred stock and noncontrolling interests	10,546
Purchase Price Allocation Adjustments [Member]
Significant Acquisitions and Disposals [Line Items]
Current assets	(54)
Property, plant and equipment	(1,670)
Goodwill	125
Other long-term assets, excluding goodwill	1,845
Current liabilities, including current maturities of long-term debt	14
Long-term liabilities, preferred stock and noncontrolling interests	$ 232