Annual report pursuant to Section 13 and 15(d)

COMPANY-SPONSORED EMPLOYEE BENEFIT PLANS - Projected Benefit Obligation, Accumulated Benefit Obligation, and Fair Value of Plan Assets for Pension Plans With an Accumulated Benefit Obligation in Excess of Plan Assets (Detail)

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COMPANY-SPONSORED EMPLOYEE BENEFIT PLANS - Projected Benefit Obligation, Accumulated Benefit Obligation, and Fair Value of Plan Assets for Pension Plans With an Accumulated Benefit Obligation in Excess of Plan Assets (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]      
Document Fiscal Year Focus 2015    
Fair value of plan assets $ 30,031 $ 30,129  
U.S. Pension Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligation, Projected Benefit Obligation Exceeds the Fair Value of the Plan Assets 36,846 37,521  
Accumulated benefit obligation, Projected Benefit Obligation Exceeds the Fair Value of the Plan Assets 34,210 34,725  
Fair value of plan assets, Projected Benefit Obligation Exceeds the Fair Value of the Plan Assets 28,887 28,828  
Projected benefit obligation, Accumulated Benefit Obligation Exceeds the Fair Value of Plan Assets 36,846 37,521  
Accumulated benefit obligation, Accumulated Benefit Obligation Exceeds the Fair Value of Plan Assets 34,210 34,725  
Fair value of plan assets, Accumulated Benefit Obligation Exceeds the Fair Value of Plan Assets 28,887 28,828  
Defined Benefit Plan, Benefit Obligation 36,846 37,521  
Service cost 1,527 1,137 $ 1,349
Interest cost 1,694 1,604 1,449
Fair value of plan assets 28,887 28,828  
U.S. Postretirement Medical Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Benefit Obligation 2,673 2,883  
Service cost 34 62 103
Interest cost 117 152 185
Fair value of plan assets 130 259  
International Pension Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligation, Projected Benefit Obligation Exceeds the Fair Value of the Plan Assets 493 510  
Accumulated benefit obligation, Projected Benefit Obligation Exceeds the Fair Value of the Plan Assets 416 426  
Fair value of plan assets, Projected Benefit Obligation Exceeds the Fair Value of the Plan Assets 247 261  
Projected benefit obligation, Accumulated Benefit Obligation Exceeds the Fair Value of Plan Assets 477 474  
Accumulated benefit obligation, Accumulated Benefit Obligation Exceeds the Fair Value of Plan Assets 401 398  
Fair value of plan assets, Accumulated Benefit Obligation Exceeds the Fair Value of Plan Assets 232 232  
Defined Benefit Plan, Benefit Obligation 1,219 1,274  
Service cost 48 43 47
Interest cost 44 49 44
Fair value of plan assets 1,014 1,042  
Benefit Obligations [Member] | U.S. Pension Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Benefit Obligation 36,846 37,521 29,508
Service cost 1,527 1,137  
Interest cost 1,694 1,604  
Defined Benefit Plan, Benefits Paid 1,056 924  
Defined Benefit Plan, Contributions by Plan Participants 0 0  
Defined Benefit Plan, Plan Amendments 0 5  
Defined Benefit Plan, Actuarial Gain (Loss) 2,840 (6,191)  
Defined Benefit Plan, Foreign Currency Exchange Rate Gain (Loss) 0 0  
Defined Benefit Plan, Purchases, Sales, and Settlements 0 0  
Defined Benefit Plan Other Benefit Obligations 0 0  
Benefit Obligations [Member] | U.S. Postretirement Medical Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Benefit Obligation 2,673 2,883 4,046
Service cost 34 62  
Interest cost 117 152  
Defined Benefit Plan, Benefits Paid 262 255  
Defined Benefit Plan, Contributions by Plan Participants 21 15  
Defined Benefit Plan, Plan Amendments 0 65  
Defined Benefit Plan, Actuarial Gain (Loss) 120 (1,069)  
Defined Benefit Plan, Foreign Currency Exchange Rate Gain (Loss) 0 0  
Defined Benefit Plan, Purchases, Sales, and Settlements 0 2,271  
Defined Benefit Plan Other Benefit Obligations 0 0  
Benefit Obligations [Member] | International Pension Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Benefit Obligation 1,219 1,274 1,076
Service cost 48 43  
Interest cost 44 49  
Defined Benefit Plan, Benefits Paid 30 26  
Defined Benefit Plan, Contributions by Plan Participants 6 5  
Defined Benefit Plan, Plan Amendments (2) 0  
Defined Benefit Plan, Actuarial Gain (Loss) (13) (194)  
Defined Benefit Plan, Foreign Currency Exchange Rate Gain (Loss) (138) (103)  
Defined Benefit Plan, Purchases, Sales, and Settlements 3 2  
Defined Benefit Plan Other Benefit Obligations 7 38  
Fair Value of Plan Assets [Member] | U.S. Pension Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Benefits Paid 1,056 924  
Defined Benefit Plan, Contributions by Plan Participants 0 0  
Fair value of plan assets 28,887 28,828 26,224
Defined Benefit Plan, Actual Return on Plan Assets 67 2,471  
Defined Benefit Plan, Contributions by Employer 1,048 1,057  
Defined Benefit Plan, Foreign Currency Exchange Rate Changes, Plan Assets 0 0  
Defined Benefit Plan, Settlements, Plan Assets 0 0  
Defined Benefit Plan Other Fair Value Of Plan Assets 0 0  
Fair Value of Plan Assets [Member] | U.S. Postretirement Medical Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Benefits Paid 261 255  
Defined Benefit Plan, Contributions by Plan Participants 21 15  
Fair value of plan assets 130 259 355
Defined Benefit Plan, Actual Return on Plan Assets 0 22  
Defined Benefit Plan, Contributions by Employer 111 122  
Defined Benefit Plan, Foreign Currency Exchange Rate Changes, Plan Assets 0 0  
Defined Benefit Plan, Settlements, Plan Assets 0 0  
Defined Benefit Plan Other Fair Value Of Plan Assets 0 0  
Fair Value of Plan Assets [Member] | International Pension Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Benefits Paid 30 26  
Defined Benefit Plan, Contributions by Plan Participants 3 3  
Fair value of plan assets 1,014 1,042 $ 931
Defined Benefit Plan, Actual Return on Plan Assets 43 106  
Defined Benefit Plan, Contributions by Employer 70 79  
Defined Benefit Plan, Foreign Currency Exchange Rate Changes, Plan Assets (113) (79)  
Defined Benefit Plan, Settlements, Plan Assets 3 2  
Defined Benefit Plan Other Fair Value Of Plan Assets $ 2 $ 30