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Intangible and Other Assets - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 6 Months Ended
Jun. 30, 2012
Jun. 30, 2011
Jun. 30, 2012
Jun. 30, 2011
Finite-Lived Intangible Assets [Line Items]        
Amortization expense of intangible and other assets $ 8.8 $ 8.9 $ 17.8 $ 17.8