Property, Plant and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, plant and equipment
Gross property, plant and equipment	$ 13,247	$ 12,182
Accumulated depreciation	(5,602)	(4,808)
Net property, plant and equipment	7,645	7,374
Depreciation expense	924	986	$ 1,048
Land
Property, plant and equipment
Gross property, plant and equipment	348	349
Fiber, conduit and other outside plant(1)
Property, plant and equipment
Gross property, plant and equipment	$ 5,980	5,362
Fiber, conduit and other outside plant(1) | Minimum
Property, plant and equipment
Depreciable lives	15 years
Fiber, conduit and other outside plant(1) | Maximum
Property, plant and equipment
Depreciable lives	45 years
Central office and other network electronics(2)
Property, plant and equipment
Gross property, plant and equipment	$ 3,855	3,614
Central office and other network electronics(2) | Minimum
Property, plant and equipment
Depreciable lives	4 years
Central office and other network electronics(2) | Maximum
Property, plant and equipment
Depreciable lives	10 years
Support assets(3)
Property, plant and equipment
Gross property, plant and equipment	$ 2,633	2,584
Support assets(3) | Minimum
Property, plant and equipment
Depreciable lives	5 years
Support assets(3) | Maximum
Property, plant and equipment
Depreciable lives	30 years
Construction in progress(4)
Property, plant and equipment
Gross property, plant and equipment	$ 431	$ 273