Postretirement Benefit Plans - Weighted Average Allocations (Details)	Dec. 31, 2018	Dec. 31, 2017
Fixed income securities and cash equivalents \| United States \| Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Targeted allocation (in percent)	65.00%
Actual plan asset allocation (in percent)	65.00%	66.00%
Fixed income securities and cash equivalents \| United States \| Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Actual plan asset allocation (in percent)	65.00%	62.00%
Fixed income securities and cash equivalents \| Non-U.S. \| Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Actual plan asset allocation (in percent)	74.00%	71.00%
Fixed income securities and cash equivalents \| Minimum \| United States \| Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Targeted allocation (in percent)	55.00%
Fixed income securities and cash equivalents \| Minimum \| Non-U.S. \| Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Targeted allocation (in percent)	60.00%
Fixed income securities and cash equivalents \| Maximum \| United States \| Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Targeted allocation (in percent)	65.00%
Fixed income securities and cash equivalents \| Maximum \| Non-U.S. \| Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Targeted allocation (in percent)	100.00%
Equity securities \| United States \| Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Targeted allocation (in percent)	35.00%
Actual plan asset allocation (in percent)	35.00%	34.00%
Equity securities \| United States \| Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Actual plan asset allocation (in percent)	35.00%	38.00%
Equity securities \| Non-U.S. \| Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Actual plan asset allocation (in percent)	26.00%	29.00%
Equity securities \| Minimum \| United States \| Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Targeted allocation (in percent)	35.00%
Equity securities \| Minimum \| Non-U.S. \| Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Targeted allocation (in percent)	0.00%
Equity securities \| Maximum \| United States \| Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Targeted allocation (in percent)	45.00%
Equity securities \| Maximum \| Non-U.S. \| Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Targeted allocation (in percent)	40.00%

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- Definition

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=112275985&loc=d3e4179-114921

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920

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Percentage of actual investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920

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