Consolidated Balance Sheets (Parenthetical) - USD ($)
$ in Thousands
Dec. 31, 2016
Dec. 31, 2015
Allowance for doubtful accounts receivable $ 1,115 $ 1,441
Preferred stock, par value $ 0.01 $ 0.01
Preferred stock, shares authorized 2,000,000 2,000,000
Preferred stock, shares issued 0 0
Common stock, par value $ 0.01 $ 0.01
Common stock, shares authorized 125,000,000 125,000,000
Series A    
Common stock, shares, issued 20,620,461 20,522,503
Series B    
Common stock, shares, issued 2,472,680 2,387,509
Treasury Stock [Member] | Series A    
Treasury stock Series A, shares held 1,416,881 1,416,881