Property, Plant and Equipment - Schedule of Carrying Value of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 8,897,361	$ 8,776,840
Less accumulated depreciation	(5,568,122)	(5,503,487)
Net property, plant and equipment	3,329,239	3,273,353
Land
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	27,936	27,945
Building and Improvements
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 351,351	351,305
Building and Improvements | Minimum
Property Plant And Equipment [Line Items]
Depreciable Lives	3 years
Building and Improvements | Maximum
Property Plant And Equipment [Line Items]
Depreciable Lives	40 years
Poles
Property Plant And Equipment [Line Items]
Depreciable Lives	30 years
Property, plant and equipment, gross	$ 270,102	266,758
Fiber
Property Plant And Equipment [Line Items]
Depreciable Lives	30 years
Property, plant and equipment, gross	$ 3,796,553	3,737,372
Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 306,931	298,912
Equipment | Minimum
Property Plant And Equipment [Line Items]
Depreciable Lives	5 years
Equipment | Maximum
Property Plant And Equipment [Line Items]
Depreciable Lives	7 years
Copper
Property Plant And Equipment [Line Items]
Depreciable Lives	20 years
Property, plant and equipment, gross	$ 3,881,801	3,850,987
Conduit
Property Plant And Equipment [Line Items]
Depreciable Lives	30 years
Property, plant and equipment, gross	$ 89,776	89,773
Tower assets
Property Plant And Equipment [Line Items]
Depreciable Lives	20 years
Property, plant and equipment, gross	$ 8,571	8,571
Finance Lease Assets
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	71,318	74,103
Other assets
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 10,675	10,553
Other assets | Minimum
Property Plant And Equipment [Line Items]
Depreciable Lives	15 years
Other assets | Maximum
Property Plant And Equipment [Line Items]
Depreciable Lives	20 years
Corporate assets
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 13,628	13,475
Corporate assets | Minimum
Property Plant And Equipment [Line Items]
Depreciable Lives	3 years
Corporate assets | Maximum
Property Plant And Equipment [Line Items]
Depreciable Lives	7 years
Construction in progress
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 68,719	$ 47,086