v2.4.0.6
Fair Value Measurements (Parenthetical) (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 9 Months Ended 3 Months Ended 9 Months Ended 3 Months Ended 9 Months Ended 3 Months Ended 9 Months Ended 3 Months Ended 9 Months Ended
Sep. 30, 2012
Sep. 30, 2011
Sep. 30, 2012
Sep. 30, 2011
Dec. 31, 2011
Sep. 30, 2012
Cost and equity method investments [Member]
Jun. 30, 2012
Cost and equity method investments [Member]
Sep. 30, 2011
Cost and equity method investments [Member]
Sep. 30, 2011
Cost and equity method investments [Member]
Sep. 30, 2012
Long Lived Assets, Including Real Estate [Member]
Jun. 30, 2012
Long Lived Assets, Including Real Estate [Member]
Sep. 30, 2011
Long Lived Assets, Including Real Estate [Member]
Sep. 30, 2011
Long Lived Assets, Including Real Estate [Member]
Sep. 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]
Sep. 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]
Sep. 30, 2012
Private Equity And Real Estate Funds [Member]
Sep. 30, 2011
Private Equity And Real Estate Funds [Member]
Sep. 30, 2012
Private Equity And Real Estate Funds [Member]
Sep. 30, 2011
Private Equity And Real Estate Funds [Member]
Dec. 31, 2011
Private Equity And Real Estate Funds [Member]
Sep. 30, 2012
Real Estate Equity Properties And Investments [Member]
Sep. 30, 2011
Real Estate Equity Properties And Investments [Member]
Sep. 30, 2012
Real Estate Equity Properties And Investments [Member]
Sep. 30, 2011
Real Estate Equity Properties And Investments [Member]
Sep. 30, 2012
Retained Interest [Member]
Jun. 30, 2012
Retained Interest [Member]
Dec. 31, 2011
Retained Interest [Member]
Sep. 30, 2011
Retained Interest [Member]
Jun. 30, 2011
Retained Interest [Member]
Dec. 31, 2010
Retained Interest [Member]
Sep. 30, 2012
Retained Interest [Member]
Fair Value, Inputs, Level 3 [Member]
Dec. 31, 2011
Retained Interest [Member]
Fair Value, Inputs, Level 3 [Member]
Sep. 30, 2012
Derivatives [Member]
Jun. 30, 2012
Derivatives [Member]
Dec. 31, 2011
Derivatives [Member]
Sep. 30, 2011
Derivatives [Member]
Jun. 30, 2011
Derivatives [Member]
Dec. 31, 2010
Derivatives [Member]
Sep. 30, 2012
Other 1 [Member]
Jun. 30, 2012
Other 1 [Member]
Sep. 30, 2011
Other 1 [Member]
Jun. 30, 2011
Other 1 [Member]
Dec. 31, 2010
Other 1 [Member]
Cumulative gain (loss) adjustment for non performance risk $ 21   $ 21   $ 11                                                           $ 21   $ 11                
Investments, Fair Value Disclosure                                                                 29 35                      
Cash Accruals Not Included In Schedule Assets Measured For Fair Value On Recurring Basis 4 3 4 3                                                                                  
Fair value assets measured on non recurring basis 1,862   1,862                     336 402 1,484 3,254 82   82   123                                              
Adjustments To Assets Measured At Fair Value On Non Recurring Basis           (105) (50) (84) (254) (473) (271) (367) (1,262)         (1) (3) (3) (16)                                                
Impairment of Long-Lived Assets Held-for-use                                             71 223 126 999                                      
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value 2,900   2,900                                               29 31 35 37 45 39     145 136 141 134 111 227 416 409 509 595 450
Individually Insignificant Recurring Fair Value Measurements 218   218                                                                                    
Individually Insignificant NonRecurring Fair Value Measurements $ 286   $ 286