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Pensions And Other Postretirement Benefits Contributions and Plan Amendments (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Defined Contribution Plan [Abstract] |  |  |
Employer contributions to defined contribution plans | $ 617 | $ 650 | $ 589
Pension Plan [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Years of service | 30 years |  |
Employer contributions | $ 1,700 | 1,230 | 3,076
Pension Plan [Member] | U.S. [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Employer contributions | 76 | 77 | 2,054
Pension Plan [Member] | U.S. [Member] | Nonqualified Plan [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Estimated contributions in next fiscal year | $ 70 |  |
Pension Plan [Member] | U.S. [Member] | Qualified Plan [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Period of time for which there are no mandatory contributions for qualified plans | 5 years |  |
Mandatory contributions over the next five years | $ 0 |  |
Pension Plan [Member] | U.S. [Member] | U.S. Hourly [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Employer contributions |  |  | 2,000
Pension Plan [Member] | Non-U.S. [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Employer contributions | 1,624 | 1,153 | 1,022
Estimated contributions in next fiscal year | 600 |  |
Pension Plan [Member] | Canada and United Kingdom [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Mandatory contributions over the next five years | 310 |  |
Other Postretirement Benefits Plan [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Employer contributions | 369 | 406 |
Other Postretirement Benefits Plan [Member] | U.S. [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Employer contributions | 325 | $ 323 | 335
Pension Plan and Other Postretirement Benefits Plan [Member] | U.S. [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Remeasurement decrease due to mortality assumptions | 264 |  | $ 888
United Kingdom and Canada [Member] | Pension Plan [Member] | Non-U.S. [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Employer contributions | $ 584 |  |

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- Definition For U.S. and Canadian hourly employees hired prior to specified dates, represents the required number of years of service, before normal retirement age, to be eligible for supplemental benefits. + References No definition available. + Details
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- Definition Period of time for which there are no significant mandatory funding requirements for the qualified defined benefit plan. + References No definition available. + Details
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