Pension and Other Postretirement Benefit Plans - Benefit Payments (Details) - United States [Member] $ in Millions	Dec. 31, 2017 USD ($)
Pension Benefits [Member]
Benefit payments including expected future services [Abstract]
Paid in 2018	$ 340
Paid in 2019	334
Paid in 2020	325
Paid in 2021	325
Paid in 2022	324
Paid in 2023-2027	1,573
Other Postretirement Benefits [Member]
Benefit payments including expected future services [Abstract]
Paid in 2018	27
Paid in 2019	26
Paid in 2020	25
Paid in 2021	23
Paid in 2022	22
Paid in 2023-2027	$ 87

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- Definition

Amount of benefits for defined benefit plan expected to be paid in five fiscal years after fifth fiscal year following latest 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 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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Amount of benefits for defined benefit plan expected to be paid in next fiscal year following latest fiscal year.

+ References

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Amount of benefits for defined benefit plan expected to be paid in fifth fiscal year following latest fiscal year.

+ References

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Amount of benefits for defined benefit plan expected to be paid in fourth fiscal year following latest fiscal year.

+ References

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Amount of benefits for defined benefit plan expected to be paid in third fiscal year following latest fiscal year.

+ References

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Amount of benefits for defined benefit plan expected to be paid in second fiscal year following latest fiscal year.

+ References

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