Description Of Business And Summary Of Significant Accounting Policies (Schedule Of Revenues From External Customers) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information
Revenues	$ 2,409	$ 2,524	$ 2,608	$ 1,355	$ 1,413	$ 1,424	$ 1,368	$ 1,371	$ 8,896	$ 5,576	$ 4,772
Customer Revenue
Segment Reporting Information
Revenues									8,099	4,899	4,253
Voice Services
Segment Reporting Information
Revenues									2,886	2,022	1,951
Data And Internet Services
Segment Reporting Information
Revenues									3,693	2,337	1,948
Video Services
Segment Reporting Information
Revenues									1,244	285	134
Other Customer Revenues
Segment Reporting Information
Revenues									276	255	220
Switched Access And Subsidy Revenue
Segment Reporting Information
Revenues									$ 797	$ 677	$ 519