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Schedule of Weighted Average Assumptions to Determine Pension Obligations (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
United States Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Discount rate	3.40%	3.90%
Salary progression rate	2.30%	2.60%
Foreign Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure
Discount rate	1.80%	1.80%
Salary progression rate	2.70%	2.70%
Postretirement Benefit Plans
Defined Benefit Plan Disclosure
Discount rate	3.40%	3.90%	3.90%
Initial medical trend	7.90%	7.30%	7.50%
Ultimate health care trend	5.00%	5.00%	5.00%
Medical cost trend rate decrease to ultimate rate in year	2026	2023	2023

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Defined benefit plan assumptions used calculating benefit obligation initial medical trend.

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- Definition

Defined benefit plan assumptions used calculating benefit obligation medical cost trend rate decrease to ultimate rate in year.

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- Definition

Defined benefit plan assumptions used calculating benefit obligation salary progression rate.

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- Definition

Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation 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 (k)(1)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Ultimate trend rate for health care cost for defined benefit postretirement 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 (l)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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