Intangible Assets - Additional Information (Detail) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Expected Amortization Expense [Line Items]
Amortization expense on identifiable intangible assets	$ 6.3	$ 5.2	$ 19.1	$ 15.5
Expected Amortization Expenses in Year one			26.0
Expected Amortization Expenses in Year two			26.0
Expected Amortization Expenses in Year three			26
Expected Amortization Expenses in Year four			26
Expected Amortization Expenses in Year five			$ 26