Summary Of Significant Accounting Policies (Narrative) (Details) $ in Millions	3 Months Ended
Mar. 31, 2020 USD ($) segment	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Summary Of Significant Accounting Policies [Abstract]
Number of Reporting Units \| segment	2
Customer surcharges	$ 49	$ 53
Video franchise fees	$ 9	11
Number of operating segments \| segment	1
Restricted cash	$ 50		$ 50
Expected customer life	4 years
Funding term	6 years
Cash and cash equivalents	$ 941		760
Accumulated deficit	(8,759)		$ (8,573)
Operating income	272	339
Net loss	$ (186)	$ (87)
Number of reportable segments \| segment	1

The amount of Universal Service Fund (USF) (primarily federal USF) surcharges collected from customers.

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Straight Line Basis Funding Term

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The amount of video franchise fees.

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Amortization period of cost capitalized in obtaining or fulfilling contract with customer, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Number of reporting units tested for impairment of goodwill. A reporting unit is an operating segment or one level below an operating segment.

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The net result for the period of deducting operating expenses from operating revenues.

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Amount of cash restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits.

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The cumulative amount of the reporting entity's undistributed earnings or deficit.

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