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Pensions and Other Postretirement Benefits - Schedule of Net Benefit Costs (Details) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2018 | Mar. 31, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items] |  |
Non-service cost components of net periodic pension and OPEB income | $ 421 | $ 329
Global OPEB Plans [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items] |  |
Service cost | 5 | 4
Interest cost | 50 | 49
Expected return on plan assets | 0 | 0
Amortization of prior service cost (credit) | (4) | (3)
Amortization of net actuarial (gains) losses | 13 | 8
Net periodic pension and OPEB (income) expense | 64 | 58
U.S. [Member] | Pension Plan [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items] |  |
Service cost including administrative expenses | 83 | 79
Interest cost | 513 | 536
Expected return on plan assets | (973) | (919)
Amortization of prior service cost (credit) | (1) | (1)
Amortization of net actuarial (gains) losses | 2 | (1)
Net periodic pension and OPEB (income) expense | (376) | (306)
Non-U.S. [Member] | Pension Plan [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items] |  |
Service cost | 66 | 46
Interest cost | 120 | 125
Expected return on plan assets | (212) | (171)
Amortization of prior service cost (credit) | 1 | 1
Amortization of net actuarial (gains) losses | 37 | 47
Net periodic pension and OPEB (income) expense | 12 | $ 48
Estimated contributions in 2018 | $ 1,200 |

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- Definition The actuarial present value of benefits attributed to the pension benefit formula to services rendered by employees during the period and administrative expenses + References No definition available. + Details
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- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(4) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Amount of prior service cost (credit) recognized in net periodic benefit cost (credit) of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(5) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Amount of contributions expected to be received by defined benefit plan from employer in fiscal year. Excludes contributions paid by employer in current fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2709-114920 + Details
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