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Significant Accounting Policies, Concentrations of Credit Risk, Revenue (Details) - Revenue [Member] - Customer Concentration Risk [Member]
3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Comcast [Member]        
Concentration Risk [Line Items]        
Customer concentration risk 62.00% 60.00% 63.00% 59.00%
Office Depot [Member]        
Concentration Risk [Line Items]        
Customer concentration risk   15.00%   16.00%