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Retirement Plans and Other Post-Retirement Benefits - Summary of Amounts Recognized in Consolidated Balance Sheets (Detail) - USD ($) $ in Millions | Dec. 31, 2017 | Dec. 31, 2016
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Pension Benefits [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Net amount recognized | $ 72.3 | $ 58.7
Other Benefits [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Net amount recognized | (50.7) | (47.9)
Other Assets [Member] | Pension Benefits [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Net amount recognized | 115.5 | 96.7
Current Liabilities [Member] | Pension Benefits [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Net amount recognized | (2.2) | (2.0)
Current Liabilities [Member] | Other Benefits [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Net amount recognized | (3.5) | (3.2)
Other Long-Term Liabilities [Member] | Pension Benefits [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Net amount recognized | (41.0) | (36.0)
Other Long-Term Liabilities [Member] | Other Benefits [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Net amount recognized | $ (47.2) | $ (44.7)

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- Definition Amount of asset (liability), recognized in statement of financial position, for defined benefit pension and other postretirement plans. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64852052&loc=d3e1703-114919 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition 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. + References No definition available. + Details
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