Summary Of Significant Accounting Policies (Schedule Of Revenues From External Customers) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Revenues	$ 1,355	$ 1,371
Customer Revenue [Member]
Segment Reporting Information [Line Items]
Revenues	1,189	1,233
Switched Access And Subsidy Revenue [Member]
Segment Reporting Information [Line Items]
Revenues	166	138
Voice Services [Member]
Segment Reporting Information [Line Items]
Revenues	467	525
Data And Internet Services [Member]
Segment Reporting Information [Line Items]
Revenues	587	575
Other Customer Revenues [Member]
Segment Reporting Information [Line Items]
Revenues	$ 135	$ 133

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 1
-Article 5

Name:	us-gaap_Revenues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration