Summary Of Significant Accounting Policies (Narrative) (Details) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Jun. 30, 2020 USD ($) segment	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Summary Of Significant Accounting Policies [Abstract]
Customer surcharges	$ 42		$ 49		$ 91	$ 102
Video franchise fees	8		11		16	21
Restricted cash	$ 60				$ 60		$ 50
Expected customer life	4 years				4 years
Funding term					7 years
Cash and cash equivalents	$ 2,290				$ 2,290		760
Accumulated deficit	(8,940)				(8,940)		$ (8,573)
Operating income	140		(5,459)		412	(5,120)
Net loss	$ (181)	$ (186)	$ (5,317)	$ (87)	$ (367)	$ (5,404)
Number of reportable segments | segment					1