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	Mar. 31, 2013	Dec. 31, 2012
Other current assets [Member]
Derivatives And Hedging Activities [Line Items]
Gross Amount	$ 53.1	$ 30.3
Offset	15.1	15.2
Net Amount in Balance Sheet	38.0	15.1
Other assets [Member]
Derivatives And Hedging Activities [Line Items]
Gross Amount	30.8	19.8
Offset	7.1	6.5
Net Amount in Balance Sheet	23.7	13.3
Other current liabilities [Member]
Derivatives And Hedging Activities [Line Items]
Gross Amount	17.8	20.2
Offset	15.1	15.2
Net Amount in Balance Sheet	2.7	5.0
Other long-term liabilities [Member]
Derivatives And Hedging Activities [Line Items]
Gross Amount	7.8	12.3
Offset	7.1	6.5
Net Amount in Balance Sheet	$ 0.7	$ 5.8