Derivative Instruments and Hedging Activities - Schedule of Effects of Master Netting Agreements on Condensed Consolidated Balance Sheets (Detail) - Cash Flow Hedges [Member] - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Other Current Assets [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gross Amount	$ 15.0	$ 14.5
Offset	8.7	13.4
Net Amount in Balance Sheet	6.3	1.1
Other Assets [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gross Amount	7.9	4.8
Offset	4.3	4.3
Net Amount in Balance Sheet	3.6	0.5
Other Current Liabilities [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gross Amount	18.2	45.8
Offset	8.7	13.4
Net Amount in Balance Sheet	9.5	32.4
Other Long-term Liabilities [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gross Amount	5.7	22.8
Offset	4.3	4.3
Net Amount in Balance Sheet	$ 1.4	$ 18.5