Description Of Business And Summary Of Significant Accounting Policies (Narrative) (Details) customer in Millions, $ in Millions	12 Months Ended
Dec. 31, 2016 USD ($) customer employee state segment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Description Of Business And Summary Of Significant Accounting Policies [Abstract]
Number of customers \| customer	5.4
Number of subscribers \| customer	4.3
Number of employees \| employee	28,300
Number of states of operation \| state	29
Customer surcharges \| $	$ 217	$ 151	$ 125
Number of operating regions \| segment	7
Number of reportable segments \| segment	1

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

No definition available.

Name:	us-gaap_NumberOfOperatingSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration