v2.4.0.8
Pension and Other Postretirement Benefit Plans - Components of Other Comprehensive Income (Detail) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]      
Total $ (3,917) $ 1,852 $ 573
Net loss amortization included in benefit cost (286) (136) (151)
Pension Plans, Defined Benefit [Member]
      
Defined Benefit Plan Disclosure [Line Items]      
Net gain (loss) arising during the period 3,189 (1,907) (1,628)
Prior service credit (cost) arising during the period 203 (13) 783
Total 3,392 (1,920) (845)
Net loss amortization included in benefit cost 407 256 196
Prior service (credit) cost amortization included in benefit cost (71) (71) 5
Total 336 185 201
Other Postretirement Benefit Plans, Defined Benefit [Member]
      
Defined Benefit Plan Disclosure [Line Items]      
Net gain (loss) arising during the period 499 (24) 106
Prior service credit (cost) arising during the period 26 78 133
Total 525 54 239
Net loss amortization included in benefit cost 23 31 38
Prior service (credit) cost amortization included in benefit cost (73) (66) (55)
Total $ (50) $ (35) $ (17)