Revenue Recognition (Disaggregation Of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 1,495	$ 1,446
Subsidy and other revenue	16	16
Total revenue	1,511	1,462
Lease revenue	13	13
Revenue from contracts with customers, performance obligation	835
Data And Internet Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,049	947
Voice Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	290	321
Video Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	74	94
Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	82	84
Consumer [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	813	787
Business And Wholesale [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 682	$ 659