Revenue Recognition (Disaggregation Of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 1,421	$ 1,426	$ 4,267	$ 4,310
Subsidy and other revenue	15	18	58	40
Total revenue	1,436	1,444	4,325	4,350
Data And Internet Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	895	848	2,637	2,531
Voice Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	341	369	1,044	1,136
Video Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	104	127	333	398
Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	81	82	253	245
Consumer [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	787	785	2,323	2,352
Business And Wholesale [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 634	$ 641	$ 1,944	$ 1,958