Commitments And Contingencies (Narrative) (Details) $ in Millions		6 Months Ended
	Jan. 30, 2020 USD ($) item	Jun. 30, 2020 USD ($) state
Operating Leases [Abstract]
Term of lease arrangements lower range		1 year
Term of lease arrangements upper range		99 years
CAF II, Remaining Properties [Member]
Regulatory Commitments [Abstract]
Annual support offered by the Federal Communications Commission		$ 313
Number of states of operation | state		25
RDOF Program [Member]
Regulatory Commitments [Abstract]
Annual support offered by the Federal Communications Commission	$ 20,400
Number of auctions | item	2
Period of support	10 years
RDOF Program, Phase I [Member]
Regulatory Commitments [Abstract]
Annual support offered by the Federal Communications Commission	$ 1,600
Period of support	10 years
Number of locations with at lest 25/3 Mbps | item	6,000,000
Minimum [Member] | RDOF Program, Phase II [Member]
Regulatory Commitments [Abstract]
Amount of support offered by the Federal Communications Commission	$ 4,400
Maximum [Member] | RDOF Program, Phase I [Member]
Regulatory Commitments [Abstract]
Amount of support offered by the Federal Communications Commission	$ 16,000