Estimated Future Amortization Expense for Identifiable Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Expected Amortization Expense [Line Items]
Estimated amortization expense 2012	$ 38,828
Estimated amortization expense 2013	38,663
Estimated amortization expense 2014	38,296
Estimated amortization expense 2015	38,018
Estimated amortization expense 2016	$ 37,079