Noncontrolling Interests (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Activity for equity attributable to noncontrolling interests
Balance at January 1	$ 122,181		$ 105,811
Net Income	26,336		27,008		19,136
Balance at December 31	137,832		122,181		105,811
Noncontrolling Interest
Activity for equity attributable to noncontrolling interests
Balance at January 1	799		730		647
Net Income	157		113		112
Distributions to noncontrolling interests	(41)		(71)		(72)
Other changes, net	393	[1]	27	[1]	43	[1]
Balance at December 31	$ 1,308		$ 799		$ 730

[1] Includes components of comprehensive income, which are disclosed separately in the Consolidated Statement of Comprehensive Income.