v2.4.0.8
Reconciliation of Beginning and Ending Balance of Pension Plan Assets Measured at Fair Value (Detail) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]    
Beginning Balance $ 7,811 $ 9,064
Actual gain on plan assets 851 285
Purchases and sales (2,184) (1,547)
Transfers in (out) 606 9
Ending Balance 7,084 7,811
Corporate Bonds
    
Defined Benefit Plan Disclosure [Line Items]    
Beginning Balance 196 189
Actual gain on plan assets 12 12
Purchases and sales (13) (14)
Transfers in (out) (33) 9
Ending Balance 162 196
Real Estate
    
Defined Benefit Plan Disclosure [Line Items]    
Beginning Balance 2,018 2,158
Actual gain on plan assets 81 84
Purchases and sales (315) (224)
Ending Balance 1,784 2,018
Private Equity
    
Defined Benefit Plan Disclosure [Line Items]    
Beginning Balance 5,039 6,055
Actual gain on plan assets 674 146
Purchases and sales (1,732) (1,162)
Transfers in (out) (39)  
Ending Balance 3,942 5,039
Hedge Funds
    
Defined Benefit Plan Disclosure [Line Items]    
Beginning Balance 558 662
Actual gain on plan assets 84 43
Purchases and sales (124) (147)
Transfers in (out) 678  
Ending Balance $ 1,196 $ 558