Description Of Business And Summary Of Significant Accounting Policies (Narrative) (Details) customer in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) employee state customer	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Mar. 19, 2018	Dec. 31, 2015 state
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Number of customers | customer	3.6
Number of subscribers | customer	3.1
Number of employees | employee	16,200
Number of states of operation | state	25
Interest rate	5.944%
Restricted cash	$ 58	$ 50
Expected customer life	4 years
Customer surcharges	$ 193	221	$ 213
Video franchise fees	$ 30	$ 40	$ 47
First Lien Notes due April 2027 [Member] | Secured Debt [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Interest rate	8.00%
Maturity date	Apr. 01, 2027
Second Lien Notes Due 4/1/2026 [Member] | Secured Debt [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Interest rate	8.50%	8.50%		8.50%
Maturity date	Apr. 01, 2026
CAF Phase II [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Number of states of operation | state	25				29
Funding term	7 years
RDOF Program [Member]
Description Of Business And Summary Of Significant Accounting Policies [Line Items]
Funding term	10 years