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