Estimated Future Amortization Expense (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012
Intangible Assets [Line Items]
2012 (October 1 through December 31)	$ 1,487	[1]
2013	9,029	[1]
2014	8,477	[1]
2015	6,642	[1]
2016	5,046	[1]
Total amortization expense	$ 30,681	[1]

[1] Approximately 45% of intangible asset amortization is attributable to a noncontrolling interest.