Annual report pursuant to Section 13 and 15(d)

Business and Summary of Significant Accounting Principles (Depreciation Useful Lives) (Details)

v3.8.0.1
Business and Summary of Significant Accounting Principles (Depreciation Useful Lives) (Details)
12 Months Ended
Dec. 31, 2017
Telephony transmission equipment and distribution facilities | Minimum  
Property, Plant and Equipment [Line Items]  
Asset Lives 5 years
Telephony transmission equipment and distribution facilities | Maximum  
Property, Plant and Equipment [Line Items]  
Asset Lives 20 years
Fiber optic cable systems | Minimum  
Property, Plant and Equipment [Line Items]  
Asset Lives 15 years
Fiber optic cable systems | Maximum  
Property, Plant and Equipment [Line Items]  
Asset Lives 25 years
Cable transmission equipment and distribution facilities | Minimum  
Property, Plant and Equipment [Line Items]  
Asset Lives 5 years
Cable transmission equipment and distribution facilities | Maximum  
Property, Plant and Equipment [Line Items]  
Asset Lives 30 years
Support equipment and systems | Minimum  
Property, Plant and Equipment [Line Items]  
Asset Lives 3 years
Support equipment and systems | Maximum  
Property, Plant and Equipment [Line Items]  
Asset Lives 20 years
Transportation equipment | Minimum  
Property, Plant and Equipment [Line Items]  
Asset Lives 5 years
Transportation equipment | Maximum  
Property, Plant and Equipment [Line Items]  
Asset Lives 13 years
Property and equipment under capital leases | Minimum  
Property, Plant and Equipment [Line Items]  
Asset Lives 12 years
Property and equipment under capital leases | Maximum  
Property, Plant and Equipment [Line Items]  
Asset Lives 20 years
Buildings  
Property, Plant and Equipment [Line Items]  
Asset Lives 25 years
Customer premise equipment | Minimum  
Property, Plant and Equipment [Line Items]  
Asset Lives 2 years
Customer premise equipment | Maximum  
Property, Plant and Equipment [Line Items]  
Asset Lives 20 years
Studio equipment | Minimum  
Property, Plant and Equipment [Line Items]  
Asset Lives 10 years
Studio equipment | Maximum  
Property, Plant and Equipment [Line Items]  
Asset Lives 15 years