Fair Value Measurements (Parenthetical) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended			3 Months Ended			6 Months Ended	3 Months Ended			6 Months Ended					3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011	Jun. 30, 2012 Cost and equity method investments [Member]	Mar. 31, 2012 Cost and equity method investments [Member]	Jun. 30, 2011 Cost and equity method investments [Member]	Jun. 30, 2011 Cost and equity method investments [Member]	Jun. 30, 2012 Long Lived Assets, Including Real Estate [Member]	Mar. 31, 2012 Long Lived Assets, Including Real Estate [Member]	Jun. 30, 2011 Long Lived Assets, Including Real Estate [Member]	Jun. 30, 2011 Long Lived Assets, Including Real Estate [Member]	Jun. 30, 2012 Fair Value, Inputs, Level 3 [Member] Cost and equity method investments [Member]	Dec. 31, 2011 Fair Value, Inputs, Level 3 [Member] Cost and equity method investments [Member]	Jun. 30, 2012 Fair Value, Inputs, Level 3 [Member] Long Lived Assets, Including Real Estate [Member]	Dec. 31, 2011 Fair Value, Inputs, Level 3 [Member] Long Lived Assets, Including Real Estate [Member]	Jun. 30, 2012 Private Equity And Real Estate Funds [Member]	Jun. 30, 2011 Private Equity And Real Estate Funds [Member]	Jun. 30, 2012 Private Equity And Real Estate Funds [Member]	Jun. 30, 2011 Private Equity And Real Estate Funds [Member]	Dec. 31, 2011 Private Equity And Real Estate Funds [Member]	Jun. 30, 2012 Real Estate Equity Properties And Investments [Member]	Jun. 30, 2011 Real Estate Equity Properties And Investments [Member]	Jun. 30, 2012 Real Estate Equity Properties And Investments [Member]	Jun. 30, 2011 Real Estate Equity Properties And Investments [Member]	Jun. 30, 2012 Retained Interest [Member]	Mar. 31, 2012 Retained Interest [Member]	Dec. 31, 2011 Retained Interest [Member]	Jun. 30, 2011 Retained Interest [Member]	Mar. 31, 2011 Retained Interest [Member]	Dec. 31, 2010 Retained Interest [Member]	Jun. 30, 2012 Retained Interest [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Retained Interest [Member] Fair Value, Inputs, Level 3 [Member]	Jun. 30, 2012 Derivatives [Member]	Mar. 31, 2012 Derivatives [Member]	Dec. 31, 2011 Derivatives [Member]	Jun. 30, 2011 Derivatives [Member]	Mar. 31, 2011 Derivatives [Member]	Dec. 31, 2010 Derivatives [Member]	Jun. 30, 2012 Other [Member]	Mar. 31, 2012 Other [Member]	Dec. 31, 2011 Other [Member]	Jun. 30, 2011 Other [Member]	Mar. 31, 2011 Other [Member]	Dec. 31, 2010 Other [Member]
Cumulative gain (loss) adjustment for non performance risk	$ 22		$ 22		$ 11																														$ 22		$ 11
Investments, Fair Value Disclosure																																	31	35
Cash Accruals Not Included In Schedule Assets Measured For Fair Value On Recurring Basis	2	1	2	1
Fair value assets measured on non recurring basis	2,110		2,110											266	402	2,014	3,254	57		57		123
Adjustments To Assets Measured At Fair Value On Non Recurring Basis						(58)	(38)	(127)	(174)	(247)	(107)	(342)	(861)					(1)	(8)	(2)	(13)
Impairment of Long-Lived Assets Held-for-use																							6	339	56	776
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	2,875		2,875																								31	34	35	45	52	39			136	117	141	111	75	227	409	390	388	595	472	450
Individually Insignificant Recurring Fair Value Measurements	157		157
Individually Insignificant NonRecurring Fair Value Measurements	$ 513		$ 513