Condensed Consolidated Balance Sheets Balance Sheet Parenthetical - USD ($)
$ in Thousands
Mar. 31, 2018
Dec. 31, 2017
Allowance for doubtful accounts $ 972 $ 1,003
Preferred Stock, Par Value (in usd per share) $ 0.0001 $ 0.0001
Preferred Stock, Shares Authorized 10,000,000 10,000,000
Preferred Stock, Shares Issued 0 0
Class B common stock    
Common Stock, Par Value (in usd per share) $ 0.0001 $ 0.0001
Common Stock, Shares Authorized 75,000,000 75,000,000
Common Stock, Shares Issued 13,631,046 14,492,846
Common Stock, Shares Outstanding 13,631,046 14,492,846
Class A common stock    
Common Stock, Par Value (in usd per share) $ 0.0001 $ 0.0001
Common Stock, Shares Authorized 750,000,000 750,000,000
Common Stock, Shares Issued 67,904,088 65,969,499
Common Stock, Shares Outstanding 67,904,088 65,969,499