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Significant Accounting Policies (Details 2) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Schedule of allowance for doubtful accounts      
Beginning allowance for doubtful accounts $ 8,835 $ 10,303 $ 6,596
Additions charged to expense 13,067 16,947 22,225
Write-offs, net of recoveries (11,878) (18,415) (18,518)
Ending allowance for doubtful accounts $ 10,024 $ 8,835 $ 10,303