Pension and Other Postretirement Benefit Plans (Accumulated Benefit Obligation in Excess of Plan Assets) (Details) - Pension Benefits - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
United States Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Projected benefit obligation	$ 3,033	$ 3,415
Accumulated benefit obligation	3,022	3,403
Fair value of plan assets	2,676	2,746
Foreign Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Projected benefit obligation	720	816
Accumulated benefit obligation	699	793
Fair value of plan assets	$ 396	$ 432

Amount of accumulated benefit obligation for defined benefit plan with accumulated benefit obligation in excess of plan assets.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
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-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2417-114920

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Amount of plan asset for defined benefit plan with accumulated benefit obligation in excess of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2417-114920

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Amount of projected benefit obligation for defined benefit pension plan with accumulated benefit obligation in excess of plan assets.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
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