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Retirement Plans and Other Post-Retirement Benefits - Schedule of Fair Value of Benefit Plan Assets (Detail) - USD ($) $ in Millions | Dec. 31, 2015 | Dec. 31, 2014
--- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | $ 594.9 | $ 638.0
Large Cap [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 175.1 | 187.6
Small and Mid Cap [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 68.7 | 61.1
International Equity [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 79.8 | 104.5
Real Estate Investment Trusts (REIT) [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 31.9 | 31.6
Fixed Income [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 222.4 | 235.0
Cash and Equivalents [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 17.0 | 18.2
Level 1 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 233.5 | 372.7
Level 1 [Member] | Large Cap [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 58.4 | 187.6
Level 1 [Member] | Small and Mid Cap [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 68.7 | 61.1
Level 1 [Member] | International Equity [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 42.2 | 65.1
Level 1 [Member] | Real Estate Investment Trusts (REIT) [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 31.9 | 31.6
Level 1 [Member] | Fixed Income [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 32.3 | 27.3
Level 2 [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 361.4 | 265.3
Level 2 [Member] | Large Cap [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 116.7 |
Level 2 [Member] | International Equity [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 37.6 | 39.4
Level 2 [Member] | Fixed Income [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 190.1 | 207.7
Level 2 [Member] | Cash and Equivalents [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | $ 17.0 | $ 18.2

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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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- Definition Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 30 -Section 35 -Paragraph 50 -URI http://asc.fasb.org/extlink&oid=49178875&loc=d3e12355-114930 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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