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Significant Accounting Policies, Concentrations of Credit Risk, Accounts Receivable (Details)
9 Months Ended 12 Months Ended
Sep. 30, 2017
Dec. 31, 2016
Trade Accounts Receivable [Member] | Customer Concentration Risk [Member] | Comcast [Member]    
Concentration Risk [Line Items]    
Customer concentration risk 74.00% 70.00%