Pension and Other Post-Retirement Benefit Plans - Additional Information (Detail) $ in Millions	3 Months Ended
Mar. 31, 2018 USD ($)
Retirement Benefits [Abstract]
Expected contribution to pension plans and post-retirement benefit plans	$ 3.1
Contributions made to pension plans	$ 0.8

Amount of contributions received and expected to be received by defined benefit plan from employer in current fiscal year.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2709-114920

Name:	us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant