Receivables - Installment Receivables (Details) - USD ($)
$ in Thousands
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Receivables [Abstract]      
Installment receivables, current $ 2,027 $ 2,309  
Installment receivables, long-term 2,685 2,318  
Total Installment Receivables 4,712 4,627  
Unearned Interest 40 42  
Unearned interest, long-term 0 0  
Total Unearned Interest 40 42  
Installment receivables net of unearned interest, current 1,987 2,267  
Installment receivables net of unearned interest, long-term 2,685 2,318  
Total installment receivables net of unearned interest 4,672 4,585  
Allowance for doubtful accounts, current (619) (1,122)  
Allowance for doubtful accounts, long-term (2,219) (1,670)  
Allowance for doubtful accounts (2,838) (2,792) $ (5,852)
Installment receivables, net 1,368 1,145  
Installment receivables, long-term 466 648  
Total installment receivables, net $ 1,834 $ 1,793