Property, Plant, & Equipment (Property, Plant And Equipment, Net) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 26,496	$ 25,541
Construction work in progress	538	903
Less: Accumulated depreciation	(12,119)	(10,639)
Property, plant and equipment, net	14,377	14,902
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	231	235
Buildings and Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 2,282	2,320
Estimated useful lives	41 years
General Support [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 1,570	1,502
General Support [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	17 years
General Support [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	5 years
Central Office Electronic Circuit Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 8,137	7,683
Central Office Electronic Circuit Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	18 years
Central Office Electronic Circuit Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	5 years
Poles [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 1,095	995
Estimated useful lives	30 years
Cable and Wire [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 10,997	10,292
Cable and Wire [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	25 years
Cable and Wire [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	15 years
Conduit [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 1,646	$ 1,611
Estimated useful lives	55 years