v2.4.0.8
Pension and Other Postretirement Benefit Plans - Components of Net Periodic Benefit Cost (Detail) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Pension Plans, Defined Benefit [Member]
      
Defined Benefit Plan Disclosure [Line Items]      
Service cost $ 682 $ 555 $ 619
Interest cost 665 661 718
Expected return on plan assets (1,097) (970) (972)
Net amortization 336 185 201
Termination benefits 58 27 59
Curtailments (23) (10) (86)
Settlements 23 18 4
Net periodic benefit cost 644 466 543
Other Postretirement Benefit Plans, Defined Benefit [Member]
      
Defined Benefit Plan Disclosure [Line Items]      
Service cost 102 82 110
Interest cost 107 121 141
Expected return on plan assets (126) (136) (142)
Net amortization (50) (35) (17)
Termination benefits 50 18 29
Curtailments (11) (7) 1
Settlements 0 0 0
Net periodic benefit cost $ 72 $ 43 $ 122