Property, Plant and Equipment - Schedule of Carrying Value of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 8,776,840	$ 8,683,479
Less accumulated depreciation	(5,503,487)	(5,273,534)
Property, plant and equipment, net	3,273,353	3,409,945
Land
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	27,945	28,337
Building and Improvements
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 351,305	355,225
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
Real Property Interests
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross		3,308
Poles
Property Plant And Equipment [Line Items]
Depreciable Lives	30 years
Property, plant and equipment, gross	$ 266,758	258,535
Fiber
Property Plant And Equipment [Line Items]
Depreciable Lives	30 years
Property, plant and equipment, gross	$ 3,737,372	3,456,398
Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 298,912	293,427
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	$ 3,850,987	3,792,366
Conduit
Property Plant And Equipment [Line Items]
Depreciable Lives	30 years
Property, plant and equipment, gross	$ 89,773	89,770
Tower assets
Property Plant And Equipment [Line Items]
Depreciable Lives	20 years
Property, plant and equipment, gross	$ 8,571	170,063
Finance Lease Assets
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	74,103	129,900
Less accumulated depreciation	(16,800)	(24,300)
Construction in progress
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	47,086	89,007
Other assets
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 10,553	11,591
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	$ 13,475	$ 5,552
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