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Allowance for Doubtful Accounts
 9 Months Ended
Sep. 30, 2017
Receivables [Abstract]  
Allowance for Doubtful Accounts

5. Allowance for Doubtful Accounts

 

     Balance at
Beginning of
Period		      Charged to
Expense		      Deductions(1)      Balance at
End of
Period		  

Nine months ended September 30, 2017

    $ 5,918        13,351        (12,978 )     $ 6,291  

Nine months ended September 30, 2016

    $ 5,137        12,812        (11,766 )     $ 6,183  

 

(1) Deductions represent accounts written off, net of recoveries.