Commitments And Contingencies (Narrative) (Details) $ in Millions	1 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($) property county item	Aug. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)
Regulatory Commitments [Abstract]
Frozen high-cost phasedown support	$ 6		$ 6
Number of households to be serviced under regulatory funded programs			774,000
Number of States in our Territory	29		29
Number of auctions | item	2
FCC Inquiry [Member]
Regulatory Commitments [Abstract]
Award in funding		$ 200
CAF II [ Member]
Regulatory Commitments [Abstract]
Annual support offered by the Federal Communications Commission			$ 332
Universal Service Fund [Member]
Regulatory Commitments [Abstract]
Frozen high-cost phasedown support	$ 198		$ 198
Auction 101 [Member]
Regulatory Commitments [Abstract]
Number of licenses | item	2
Number of counties | county	1,536
Auction 102 [Member]
Regulatory Commitments [Abstract]
Number of licenses | item	7
Number of Economic Areas | property	416