Commitments And Contingencies (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Regulatory Commitments [Abstract]
Frozen high-cost phasedown support	$ 6
Number of households to be serviced under regulatory funded programs	774,000
Number of States in our Territory	29
CAF II [ Member]
Regulatory Commitments [Abstract]
Annual support offered by the Federal Communications Commission	$ 332