Pensions Benefit Plans and Other Postretirement Benefits - Weighted Average Assumptions Assumed and Effect of Percentage Point Change in Health Care Cost Trend (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure
Payments to the trust as required by the bargaining agreements are based upon specified amounts per hour worked	$ 6	$ 6	$ 6
U.S Postretirement Benefit Plans
Weighted average assumed health care cost trend (in percent)
Health care cost trend rate assumed for next year (as a percent)	6.20%	6.40%
Rate to which the cost trend rate is assumed to decline (ultimate trend rate) (as a percent)	5.00%	5.00%
Year that the rate reaches the ultimate trend rate	2024	2024
Effect of one-percentage-point change in assumed health care cost trend rates (in percent)
One-Percentage-Point Increase, effect on accumulated postretirement benefit obligations	$ (4)
One-Percentage-Point Decrease, effect on accumulated postretirement benefit obligations	$ 4
Non-U.S. Postretirement Benefit Plans
Weighted average assumed health care cost trend (in percent)
Health care cost trend rate assumed for next year (as a percent)	5.00%	5.00%
Rate to which the cost trend rate is assumed to decline (ultimate trend rate) (as a percent)	5.00%	5.00%
Effect of one-percentage-point change in assumed health care cost trend rates (in percent)
One-Percentage-Point Decrease, effect on total of service and interest cost	$ 1
One-Percentage-Point Increase, effect on accumulated postretirement benefit obligations	(6)
One-Percentage-Point Decrease, effect on accumulated postretirement benefit obligations	$ 8

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Amount of effect of a one-percentage-point decrease in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits.

+ 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 (m)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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Amount of effect of a one-percentage-point decrease in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs.

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The effect of a one-percentage-point increase in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits.

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The assumed health care cost trend rate for the next year used to measure the expected cost of benefits covered by the plan (gross eligible charges). This is based upon the annual rate of change in the cost of health care benefits currently provided by the postretirement benefit plan, due to factors other than changes in the composition of the plan population by age and dependency status.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Health Care Cost Trend Rate
-URI http://asc.fasb.org/extlink&oid=6514820

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The ultimate trend rate for health care costs.

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Year the ultimate health care cost trend rate is expected to be reached, in CCYY format.

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Amount of contributions made to multiemployer plans by the employer. A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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