Property, Plant and Equipment - Components (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	$ 16,301	$ 17,775
Accumulated depreciation	(8,789)	(8,910)
Net property, plant and equipment	7,512	8,865
Land
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	328	329
Fiber, conduit and other outside plant
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	$ 7,300	8,246
Fiber, conduit and other outside plant | Minimum
Property, Plant and Equipment [Line Items]
Depreciable Lives	15 years
Fiber, conduit and other outside plant | Maximum
Property, Plant and Equipment [Line Items]
Depreciable Lives	45 years
Central office and other network electronics
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	$ 5,506	5,792
Central office and other network electronics | Minimum
Property, Plant and Equipment [Line Items]
Depreciable Lives	7 years
Central office and other network electronics | Maximum
Property, Plant and Equipment [Line Items]
Depreciable Lives	10 years
Support assets
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	$ 2,869	2,878
Support assets | Minimum
Property, Plant and Equipment [Line Items]
Depreciable Lives	3 years
Support assets | Maximum
Property, Plant and Equipment [Line Items]
Depreciable Lives	30 years
Construction in progress
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	$ 298	$ 530