v2.4.0.8
Fair Values for Plans by Asset Category (Detail) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category $ 3,053 $ 2,657  
Cash and Cash Equivalents
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 237 291  
Equity Securities
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 2,178 1,753  
US Treasuries and agencies
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 121 118  
Corporate Bonds
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 252 192  
International Bonds
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 104 189  
Other Fixed Income Securities
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 161 114  
Level 1
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 1,533 1,180  
Level 1 | Cash and Cash Equivalents
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 12 13  
Level 1 | Equity Securities
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 1,324 1,004  
Level 1 | US Treasuries and agencies
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 94 80  
Level 1 | Corporate Bonds
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 45 11  
Level 1 | International Bonds
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 18 72  
Level 1 | Other Fixed Income Securities
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 40    
Level 2
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 1,520 1,477  
Level 2 | Cash and Cash Equivalents
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 225 278  
Level 2 | Equity Securities
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 854 749  
Level 2 | US Treasuries and agencies
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 27 38  
Level 2 | Corporate Bonds
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 207 181  
Level 2 | International Bonds
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 86 117  
Level 2 | Other Fixed Income Securities
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 121 114  
Pension
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 17,111 18,282 24,110
Pension | Cash and Cash Equivalents
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 968 1,618  
Pension | Equity Securities
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 4,200 2,944  
Pension | US Treasuries and agencies
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 1,097 1,589  
Pension | Corporate Bonds
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 2,953 2,456  
Pension | International Bonds
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 364 601  
Pension | Other Fixed Income Securities
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 3 210  
Pension | Real Estate
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 1,784 2,018  
Pension | Private Equity
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 3,942 5,039  
Pension | Hedge Funds
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 1,800 1,807  
Pension | Level 1
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 5,135 5,355  
Pension | Level 1 | Cash and Cash Equivalents
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 881 1,586  
Pension | Level 1 | Equity Securities
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 3,300 2,469  
Pension | Level 1 | US Treasuries and agencies
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 691 1,125  
Pension | Level 1 | Corporate Bonds
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 212 35  
Pension | Level 1 | International Bonds
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 51 140  
Pension | Level 2
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 4,892 5,116  
Pension | Level 2 | Cash and Cash Equivalents
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 87 32  
Pension | Level 2 | Equity Securities
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 900 475  
Pension | Level 2 | US Treasuries and agencies
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 406 464  
Pension | Level 2 | Corporate Bonds
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 2,579 2,225  
Pension | Level 2 | International Bonds
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 313 461  
Pension | Level 2 | Other Fixed Income Securities
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 3 210  
Pension | Level 2 | Hedge Funds
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 604 1,249  
Pension | Level 3
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 7,084 7,811  
Pension | Level 3 | Corporate Bonds
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 162 196  
Pension | Level 3 | Real Estate
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 1,784 2,018  
Pension | Level 3 | Private Equity
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category 3,942 5,039  
Pension | Level 3 | Hedge Funds
      
Defined Benefit Plan Disclosure [Line Items]      
Fair values for the pension plans by asset category $ 1,196 $ 558