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Post-Employment and Other Long-Term Employees Benefits - Pension Plan Asset Allocation (Detail)	Dec. 31, 2017	Dec. 31, 2016
Allocation of pension plan assets	100.00%	100.00%
Cash and Cash Equivalents [Member]
Allocation of pension plan assets	3.00%	2.00%
Equity Securities [Member]
Allocation of pension plan assets	30.00%	29.00%
Government Debt Securities [Member]
Allocation of pension plan assets	3.00%	3.00%
Corporate Debt Securities [Member]
Allocation of pension plan assets	26.00%	26.00%
Investment Funds [Member]
Allocation of pension plan assets	17.00%	18.00%
Real Estate [Member]
Allocation of pension plan assets	2.00%	2.00%
Other (Mainly Insurance Assets - Contracts and Reserves) [Member]
Allocation of pension plan assets	19.00%	20.00%

X

- Definition

Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2446-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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