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Summary Of Significant Accounting Policies (Narrative) (Details) $ in Millions				3 Months Ended						9 Months Ended
	Oct. 08, 2020 USD ($)	Aug. 13, 2020 USD ($)	May 15, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Sep. 30, 2020 USD ($) segment	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Debt Instrument [Line Items]
Customer surcharges				$ 51			$ 60			$ 142	$ 162
Video franchise fees				7			10			23	31
Restricted cash				$ 58						$ 58		$ 50
Expected customer life				4 years						4 years
Funding term										7 years
Cash and cash equivalents				$ 1,767						$ 1,767		760
Accumulated deficit				(8,925)						(8,925)		(8,573)
Operating income				270			26			682	(5,094)
Net loss				15	$ (181)	$ (186)	$ (345)	$ (5,317)	$ (87)	$ (352)	$ (5,749)
Number of reportable segments \| segment										1
Principal Outstanding				16,762						$ 16,762		17,516
Secured Debt [Member]
Debt Instrument [Line Items]
Principal Outstanding				4,957						$ 4,957		5,711
DIP Revolving Facility [Member]
Debt Instrument [Line Items]
DIP, Maximum line of credit		$ 625	$ 460
New First Lien Notes [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date										Oct. 15, 2027
First Lien Notes Due 4/1/2027 [Member] \| Secured Debt [Member]
Debt Instrument [Line Items]
Principal Outstanding				$ 1,650						$ 1,650		$ 1,650
Interest rate				8.00%						8.00%		8.00%
Debt instrument, maturity date										Apr. 01, 2027
Second Lien Notes Due 4/1/2026 [Member] \| Secured Debt [Member]
Debt Instrument [Line Items]
Principal Outstanding				$ 1,600						$ 1,600		$ 1,600
Interest rate				8.50%						8.50%		8.50%
Debt instrument, maturity date										Apr. 01, 2026
Subsequent Event [Member] \| DIP Revolving Facility [Member]
Debt Instrument [Line Items]
DIP, Maximum line of credit	$ 625
Subsequent Event [Member] \| DIP Term Loan Facility [Member]
Debt Instrument [Line Items]
DIP, Maximum line of credit	500
Subsequent Event [Member] \| New First Lien Notes [Member]
Debt Instrument [Line Items]
Principal Outstanding	$ 1,150
Interest rate	5.875%
Debt instrument, maturity date	Oct. 15, 2027