Fair Value of Derivative Instruments (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Derivatives assets	$ 20.4	$ 12.6
Derivatives liabilities	3.9	6.8
Derivatives designated as accounting hedges
Derivatives, Fair Value [Line Items]
Derivatives assets	18.4	11.5
Derivatives liabilities	3.3	4.5
Derivatives designated as accounting hedges | Interest rate swaps | Other Assets
Derivatives, Fair Value [Line Items]
Derivatives assets	18.4	11.5
Derivatives designated as accounting hedges | Interest rate swaps | Accounts payable and accrued liabilities
Derivatives, Fair Value [Line Items]
Derivatives liabilities	1.5	4.5
Derivatives designated as accounting hedges | Foreign exchange forward | Net Investment Hedging | Accounts payable and accrued liabilities
Derivatives, Fair Value [Line Items]
Derivatives liabilities	1.8
Derivatives not designated as accounting hedges | Foreign exchange forward | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivatives assets	2.0	1.1
Derivatives not designated as accounting hedges | Foreign exchange forward | Accounts payable and accrued liabilities
Derivatives, Fair Value [Line Items]
Derivatives liabilities	$ 0.6	$ 2.3