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Organization and Summary of Significant Accounting Policies, Trade Accounts Receivable and Allowance for Doubtful Accounts (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Allowance for Doubtful Accounts [Member]    
Summary of allowance for doubtful accounts [Roll Forward]    
Balance at beginning of period $ 19 $ 6
Adjustments to costs and expenses 34 37
Write-offs (44) (24)
Balance at end of period $ 9 $ 19
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Comcast [Member]    
Concentration Risk [Line Items]    
Customer concentration risk 71.00% 70.00%
Accounts Receivable [Member] | Customer Concentration Risk [Member] | CoxCom [Member]    
Concentration Risk [Line Items]    
Customer concentration risk 12.00%