Retirement Plans and Other Post-Retirement Benefits - Summary of Amounts Recognized in Consolidated Balance Sheets (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net amount recognized	$ 58.7	$ 53.0
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net amount recognized	(47.9)	(50.9)
Other Assets [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net amount recognized	96.7	89.1
Current Liabilities [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net amount recognized	(2.0)	(2.1)
Current Liabilities [Member] | Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net amount recognized	(3.2)	(3.2)
Other Long-Term Liabilities [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net amount recognized	(36.0)	(34.0)
Other Long-Term Liabilities [Member] | Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net amount recognized	$ (44.7)	$ (47.7)