Property, Plant and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, plant and equipment
Asset Retirement Obligation	$ 115	$ 95	$ 91	$ 107
Gross property, plant and equipment	51,204	39,194
Accumulated depreciation	(24,352)	(22,155)
Net property, plant and equipment	26,852	17,039
Depreciation, Depletion and Amortization [Abstract]
Depreciation expense	2,710	2,691	$ 2,836
Land
Property, plant and equipment
Gross property, plant and equipment	883	563
Fiber, conduit and other outside plant(1)
Property, plant and equipment
Gross property, plant and equipment	$ 22,798	16,996
Fiber, conduit and other outside plant(1) | Minimum
Depreciation, Depletion and Amortization [Abstract]
Depreciable Lives	15 years
Fiber, conduit and other outside plant(1) | Maximum
Depreciation, Depletion and Amortization [Abstract]
Depreciable Lives	45 years
Central office and other network electronics(2)
Property, plant and equipment
Gross property, plant and equipment	$ 18,538	13,768
Central office and other network electronics(2) | Minimum
Depreciation, Depletion and Amortization [Abstract]
Depreciable Lives	3 years
Central office and other network electronics(2) | Maximum
Depreciation, Depletion and Amortization [Abstract]
Depreciable Lives	10 years
Support assets(3)
Property, plant and equipment
Gross property, plant and equipment	$ 7,586	6,623
Support assets(3) | Minimum
Depreciation, Depletion and Amortization [Abstract]
Depreciable Lives	3 years
Support assets(3) | Maximum
Depreciation, Depletion and Amortization [Abstract]
Depreciable Lives	30 years
Construction in progress(4)
Property, plant and equipment
Gross property, plant and equipment	$ 1,399	$ 1,244