v2.4.0.8
Fair Values For Other Postretirement Benefit Plans By Asset Category (Detail) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
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