Summary Of Significant Accounting Policies (Schedule Of Revenues From External Customers) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Revenues	$ 1,424	$ 1,141	$ 4,163	$ 3,442
Customer Revenue [Member]
Segment Reporting Information [Line Items]
Revenues	1,223	1,017	3,692	3,051
Switched Access And Subsidy Revenue [Member]
Segment Reporting Information [Line Items]
Revenues	201	124	471	391
Voice Services [Member]
Segment Reporting Information [Line Items]
Revenues	500	472	1,540	1,426
Data And Internet Services [Member]
Segment Reporting Information [Line Items]
Revenues	589	469	1,748	1,393
Other Customer Revenues [Member]
Segment Reporting Information [Line Items]
Revenues	$ 134	$ 76	$ 404	$ 232