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	Jun. 30, 2013	Dec. 31, 2012
Other current assets [Member]
Derivatives And Hedging Activities [Line Items]
Gross Amount	$ 55.2	$ 30.3
Offset	7.6	15.2
Net Amount in Balance Sheet	47.6	15.1
Other assets [Member]
Derivatives And Hedging Activities [Line Items]
Gross Amount	31.9	19.8
Offset	5.3	6.5
Net Amount in Balance Sheet	26.6	13.3
Other current liabilities [Member]
Derivatives And Hedging Activities [Line Items]
Gross Amount	9.6	20.2
Offset	7.6	15.2
Net Amount in Balance Sheet	2.0	5.0
Other long-term liabilities [Member]
Derivatives And Hedging Activities [Line Items]
Gross Amount	5.5	12.3
Offset	5.3	6.5
Net Amount in Balance Sheet	$ 0.2	$ 5.8