Acquisitions and Sales of Other Assets (Narrative - Change in PPA) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013
Significant Acquisitions and Disposals [Line Items]
Current assets	$ 3,204
Property, plant and equipment	23,122
Goodwill	12,477
Other long-term assets, excluding goodwill	9,992
Current liabilities, including current maturities of long-term debt	3,590
Long-term liabilities, preferred stock and noncontrolling interests	10,388
Purchase Price Allocation Adjustments [Member]
Significant Acquisitions and Disposals [Line Items]
Property, plant and equipment	(157)
Goodwill	10
Current liabilities, including current maturities of long-term debt	9
Long-term liabilities, preferred stock and noncontrolling interests	$ (158)