|**Pension and Postretirement Benefit Plans (Tables)**                                                                                                                                                    | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
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|**Retirement Benefits [Abstract]**                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Schedule of Net Periodic Benefit Costs                                                                                                                                                                   | The following table provides the components of net periodic benefit cost/(credit):Three Months EndedPension PlansU.S.QualifiedU.S. Supplemental(Non-Qualified)InternationalPostretirementPlans(MILLIONS OF DOLLARS)March 29, 2020March 31, 2019March 29, 2020March 31, 2019March 29, 2020March 31, 2019March 29, 2020March 31, 2019Service cost$—$—$—$—$36$32$10$9Interest cost131157101242541319Expected return on plan assets(252)(223)——(78)(80)(9)(8)Amortization of:Actuarial losses3237423120—1Prior service credits(1)(1)——(1)(1)(43)(45)Settlements14138—1———Special termination benefits——16————$(76)$(28)$52$20$32$25$(30)$(23)The following table provides the amounts we contributed, and the amounts we expect to contribute during 2020, to our pension and postretirement plans from our general assets for the periods indicated:Pension Plans(MILLIONS OF DOLLARS)U.S. QualifiedU.S. Supplemental (Non-Qualified)InternationalPostretirement PlansContributions from our general assets for the three months ended March 29, 2020$3$132$46$45Expected contributions from our general assets during 2020(a)1,276228186155
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|The following table provides the components of net periodic benefit cost/(credit):                                                                                                                      
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|(MILLIONS OF DOLLARS)                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Service cost                                                                                                                                                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Interest cost                                                                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Expected return on plan assets                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Amortization of:                                                                                                                                                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Actuarial losses                                                                                                                                                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Prior service credits                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Settlements                                                                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Special termination benefits                                                                                                                                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
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|The following table provides the amounts we contributed, and the amounts we expect to contribute during 2020, to our pension and postretirement plans from our general assets for the periods indicated:
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|(MILLIONS OF DOLLARS)                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Contributions from our general assets for the three months ended March 29, 2020                                                                                                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Expected contributions from our general assets during 2020(a)                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Schedule of Employer Contributions to Pension and Postretirement Plans                                                                                                                                   | The following table provides the amounts we contributed, and the amounts we expect to contribute during 2020, to our pension and postretirement plans from our general assets for the periods indicated:Pension Plans(MILLIONS OF DOLLARS)U.S. QualifiedU.S. Supplemental (Non-Qualified)InternationalPostretirement PlansContributions from our general assets for the three months ended March 29, 2020$3$132$46$45Expected contributions from our general assets during 2020(a)1,276228186155(a)Contributions expected to be made for2020are inclusive of amounts contributed during thethree months ended March 29, 2020. The U.S. supplemental (non-qualified) pension plan, international pension plan and the postretirement plan contributions from our general assets include direct employer benefit payments. For the U.S. qualified plans, we plan to make a$1.25 billionvoluntary contribution in the second half of 2020.                                                                                                                                                                                                  
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|The following table provides the amounts we contributed, and the amounts we expect to contribute during 2020, to our pension and postretirement plans from our general assets for the periods indicated:
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|(MILLIONS OF DOLLARS)                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Contributions from our general assets for the three months ended March 29, 2020                                                                                                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Expected contributions from our general assets during 2020(a)                                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          

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