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Accounts Receivable (Allowance For Doubtful Accounts Related To Accounts Receivable) (Detail) (USD $)
In Thousands, unless otherwise specified
6 Months Ended
Jun. 30, 2012
Jun. 30, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Allowance for doubtful accounts beginning of period $ 15,315 $ 14,256
Provision for bad debts 10,953 8,771
Write-offs (8,309) (6,682)
Allowance for doubtful accounts end of period $ 17,959 $ 16,345