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
 3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
U.S. Pension Benefits        
Net Periodic Cost:        
Service cost $ 382 $ 353 $ 1,161 $ 1,059
Interest cost 445 457 1,369 1,371
Expected return on assets (730) (629) (2,154) (1,887)
Amortization of:        
Amortization of prior service cost 48 41 144 125
Net periodic benefit cost 145 222 520 668
U.S. Postretirement Medical Benefits        
Net Periodic Cost:        
Service cost 7 7 21 21
Interest cost 28 32 84 92
Expected return on assets (2) (2) (5) (4)
Amortization of:        
Amortization of prior service cost 1 1 5 3
Net periodic benefit cost 34 38 105 112
International Pension Benefits        
Net Periodic Cost:        
Service cost 15 12 44 37
Interest cost 10 10 30 31
Expected return on assets (17) (15) (49) (44)
Amortization of:        
Amortization of prior service cost 1 0 1 0
Net periodic benefit cost $ 9 $ 7 $ 26 $ 24