v2.4.0.6
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