Derivative Instruments and Hedging Activities - Schedule of Effects of Master Netting Agreements on Consolidated Balance Sheets (Detail) - Cash Flow Hedges [Member] - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Other Current Assets [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gross Amount	$ 14.5	$ 57.9
Offset	13.4	20.6
Net Amount in Balance Sheet	1.1	37.3
Other Assets [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gross Amount	4.8	34.9
Offset	4.3	6.8
Net Amount in Balance Sheet	0.5	28.1
Other Current Liabilities [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gross Amount	45.8	20.9
Offset	13.4	20.6
Net Amount in Balance Sheet	32.4	0.3
Other Long-term Liabilities [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gross Amount	22.8	6.9
Offset	4.3	6.8
Net Amount in Balance Sheet	$ 18.5	$ 0.1