Summary of Principal Accounting Policies (Property) (Details) (USD $) In Millions, unless otherwise specified			12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Building [Member] years	Dec. 31, 2011 Machinery and Equipment [Member] years
Property, Plant and Equipment [Line Items]
Land	$ 76	$ 74
Buildings	1,208	1,218
Machinery and equipment	7,964	8,502
Accumulated depreciation	(6,146)	(6,660)
Property, net	$ 3,102	$ 3,134
Property, Plant and Equipment, Useful Life, Minimum			25	3
Property, Plant and Equipment, Useful Life, Maximum			50	25