Property, Plant and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment, Net [Abstract]
Property, Plant and Equipment, Gross	$ 21,388	$ 20,243
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(11,249)	(10,365)
Net	10,139	9,878
Depreciation expense	1,039	939	$ 713
Land
Property, Plant and Equipment, Net [Abstract]
Property, Plant and Equipment, Gross	179	180
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	0	0
Net	179	180
Land Improvements
Property, Plant and Equipment, Net [Abstract]
Property, Plant and Equipment, Gross	77	76
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(58)	(53)
Net	19	23
Facility and Leasehold Improvements
Property, Plant and Equipment, Net [Abstract]
Property, Plant and Equipment, Gross	2,679	2,582
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(1,447)	(1,352)
Net	1,232	1,230
Network infrastructure
Property, Plant and Equipment, Net [Abstract]
Property, Plant and Equipment, Gross	9,110	8,979
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(3,899)	(3,669)
Net	5,211	5,310
Operating Equipment
Property, Plant and Equipment, Net [Abstract]
Property, Plant and Equipment, Gross	8,846	7,988
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(5,626)	(5,079)
Net	3,220	2,909
Furniture, Fixtures and Office Equipment
Property, Plant and Equipment, Net [Abstract]
Property, Plant and Equipment, Gross	241	242
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(196)	(189)
Net	45	53
Other
Property, Plant and Equipment, Net [Abstract]
Property, Plant and Equipment, Gross	26	28
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(23)	(23)
Net	3	5
Construction-in-Progress
Property, Plant and Equipment, Net [Abstract]
Property, Plant and Equipment, Gross	230	168
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	0	0
Net	$ 230	$ 168