Description Of Business And Summary Of Significant Accounting Policies (Narrative) (Details) item in Millions, customer in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) employee state segment customer item	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Number of customers | customer	3.4
Number of subscribers | item	2.5
Number of employees | employee	19,200
Number of states of operation | state	28
Proceeds on sale of interest	$ 22	$ 39	$ 18
Gain on sale of Mohave partnership interest			15
Customer surcharges	$ 151	$ 125	$ 118
Number of operating regions | segment	6
Number of reportable segments | segment	1
Mohave Cellular Limited Partnership [Member]
Ownership percentage of subsidiary sold (in hundredths)			33.33%
Gain on sale of Mohave partnership interest			$ 15