Summary Of Significant Accounting Policies (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($) segment	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Summary Of Significant Accounting Policies [Abstract]
Number of reportable segments | segment	1
Customer surcharges	$ 53	$ 57
Video franchise fees	$ 11	$ 12
Number of operating segments | segment	1
Restricted cash	$ 50		$ 50
Expected customer life	3 years 9 months 18 days
Funding term	6 years