Commitments And Contingencies (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) Property State
Regulatory Commitments [Abstract]
Number of states of operation | State	29
Operating Leases [Abstract]
Term Of Lease Arrangements Lower Range	1 year
Term Of Lease Arrangements Upper Range	99 years
CAF Phase II [Member]
Regulatory Commitments [Abstract]
Annual support offered by the Federal Communications Commission	$ 332
Number of households to be serviced under regulatory funded programs | Property	774,000
Number of states of operation | State	29
Amount of annual USF frozen high-cost support	$ 198
CAF II, Four States [Member]
Regulatory Commitments [Abstract]
Annual support offered by the Federal Communications Commission	$ 19
Number of states of operation | Property	4