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, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Other Current Assets [Member]
Derivatives And Hedging Activities [Line Items]
Gross Amount	$ 98.7	$ 60.2
Offset	15.9	13.5
Net Amount in Balance Sheet	82.8	46.7
Other Assets [Member]
Derivatives And Hedging Activities [Line Items]
Gross Amount	53.1	30.2
Offset	10.4	8.2
Net Amount in Balance Sheet	42.7	22.0
Other Current Liabilities [Member]
Derivatives And Hedging Activities [Line Items]
Gross Amount	16.4	26.4
Offset	15.9	13.5
Net Amount in Balance Sheet	0.5	12.9
Other Long-term Liabilities [Member]
Derivatives And Hedging Activities [Line Items]
Gross Amount	11.6	15.9
Offset	10.4	8.2
Net Amount in Balance Sheet	$ 1.2	$ 7.7