Quarterly report pursuant to Section 13 or 15(d)

Net Periodic Benefit Cost for Pension and Postretirement Benefit Plans (Detail)

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Net Periodic Benefit Cost for Pension and Postretirement Benefit Plans (Detail) (USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2013
Mar. 31, 2012
U.S. Pension Benefits
    
Net Periodic Cost:    
Service cost $ 338 $ 249
Interest cost 362 353
Expected return on assets (537) (492)
Amortization of:    
Transition obligation 0 0
Other net (gain) loss 0 0
Prior service cost 43 43
Actuarial (gain) loss 0 0
Net periodic benefit cost 206 153
U.S. Postretirement Medical Benefits
    
Net Periodic Cost:    
Service cost 26 22
Interest cost 46 52
Expected return on assets (8) (4)
Amortization of:    
Transition obligation 0 0
Other net (gain) loss 0 0
Prior service cost 1 1
Actuarial (gain) loss 0 0
Net periodic benefit cost 65 71
International Pension Benefits
    
Net Periodic Cost:    
Service cost 15 15
Interest cost 11 11
Expected return on assets (14) (12)
Amortization of:    
Transition obligation 0 0
Other net (gain) loss 0 0
Prior service cost 0 0
Actuarial (gain) loss 0 0
Net periodic benefit cost $ 12 $ 14