Annual report pursuant to Section 13 and 15(d)

Employee Benefit Plans - Fair Value Measurements (Details)

v2.4.0.6
Employee Benefit Plans - Fair Value Measurements (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair value, December 31 $ 5,064 $ 4,827  
Level 3
      
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair value, January 1 258 254 266
Actual Return on Plan Assets Still Held at the Reporting Date 5 (7) 5
Purchases 66 17 27
Sales and Settlements (15) (6) 0
Transfers Into/(Out of) Level 3 0 0 (44)
Fair value, December 31 314 258 254
Limited partnerships
      
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair value, December 31 180 181  
Limited partnerships | Level 3
      
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair value, January 1 176 175 111
Actual Return on Plan Assets Still Held at the Reporting Date 4 (7) 10
Purchases 10 13 2
Sales and Settlements (15) (5) 0
Transfers Into/(Out of) Level 3 0 0 52
Fair value, December 31 175 176 175
Other investments
      
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair value, December 31 473 [1] 553 [2]  
Other investments | Level 3
      
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair value, January 1     110
Actual Return on Plan Assets Still Held at the Reporting Date     0
Purchases     0
Sales and Settlements     0
Transfers Into/(Out of) Level 3     (110)
Fair value, December 31 0 [1] 0 [2] 0
U.S. Government and government agency obligations | Level 3
      
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair value, January 1 13 14 0
Actual Return on Plan Assets Still Held at the Reporting Date 0 (1) 0
Purchases 0 0 0
Sales and Settlements 0 0 0
Transfers Into/(Out of) Level 3 0 0 14
Fair value, December 31 13 13 14
Mutual funds | Real estate
      
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair value, December 31 136 80  
Mutual funds | Real estate | Level 3
      
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair value, January 1 69 65 45
Actual Return on Plan Assets Still Held at the Reporting Date 1 1 (5)
Purchases 56 4 25
Sales and Settlements 0 (1) 0
Transfers Into/(Out of) Level 3 0 0 0
Fair value, December 31 $ 126 $ 69 $ 65
[1] Other investments includes swaps of $311 million, commodity and balanced funds of $158 million, and various other investments of $4 million.
[2] Other investments includes swaps of $465 million and commodity and balanced funds of