Amortizable Intangible Assets - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Finite Lived Intangible Assets Amortization Expense [Line Items]
Amortization expense for amortizable intangible assets	$ 63,573,000	$ 54,755,000	$ 51,442,000
Amortization expense estimated, year one (2013)	64,082,000
Amortization expense estimated, year two (2014)	63,020,000
Amortization expense estimated, year three (2015)	61,730,000
Amortization expense estimated, year four (2016)	57,149,000
Amortization expense estimated, year five (2017)	$ 54,437,000