Retirement Benefit Plans - Additional Information (Detail)	9 Months Ended
Sep. 30, 2018 USD ($)
Foreign-based Defined Benefit Plans [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Contribution towards defined benefit plans	$ 14,500,000
Expected contribution during remainder of year	4,800,000
US and Foreign [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Contribution towards defined benefit plans	0
Expected contribution during remainder of year	$ 0

Amount of contribution received by defined benefit plan from employer which increases plan assets.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
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Reference 2: http://www.xbrl.org/2003/role/exampleRef
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-Name Accounting Standards Codification
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-Publisher FASB
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
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-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanContributionsByEmployer
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration