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 9 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Sep. 30, 2013
Sep. 30, 2012
U.S. Pension Benefits
        
Net Periodic Cost:        
Service cost $ 337 $ 249 $ 1,012 $ 748
Interest cost 362 353 1,087 1,058
Expected return on assets (537) (493) (1,611) (1,478)
Amortization of:        
Transition obligation 0 0 0 0
Other net (gain) loss 0 0 0 0
Prior service cost 44 43 130 130
Actuarial (gain) loss 0 0 0 0
Net periodic benefit cost 206 152 618 458
U.S. Postretirement Medical Benefits
        
Net Periodic Cost:        
Service cost 20 23 72 67
Interest cost 46 52 139 156
Expected return on assets (8) (4) (25) (13)
Amortization of:        
Transition obligation 0 0 0 0
Other net (gain) loss 0 0 0 0
Prior service cost 1 1 3 3
Actuarial (gain) loss 0 0 0 0
Net periodic benefit cost 59 72 189 213
International Pension Benefits
        
Net Periodic Cost:        
Service cost 11 12 37 41
Interest cost 11 10 33 31
Expected return on assets (14) (11) (42) (35)
Amortization of:        
Transition obligation 0 0 0 0
Other net (gain) loss 0 0 0 0
Prior service cost 0 1 0 1
Actuarial (gain) loss 0 0 0 0
Net periodic benefit cost $ 8 $ 12 $ 28 $ 38