Schedule III - Real Estate Investments and Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Real Estate And Accumulated Depreciation [Line Items]
Gross Amount Carried at Close of Period	$ 7,387,915	$ 7,394,951	$ 7,000,099
Accumulated Depreciation	5,205,395	$ 5,022,929	$ 4,739,126
Land
Real Estate And Accumulated Depreciation [Line Items]
Gross Amount Carried at Close of Period	26,596
Building and Improvements
Real Estate And Accumulated Depreciation [Line Items]
Gross Amount Carried at Close of Period	335,495
Accumulated Depreciation	$ 184,021
Building and Improvements | Minimum
Real Estate And Accumulated Depreciation [Line Items]
Depreciable Lives	3 years
Building and Improvements | Maximum
Real Estate And Accumulated Depreciation [Line Items]
Depreciable Lives	40 years
Poles
Real Estate And Accumulated Depreciation [Line Items]
Gross Amount Carried at Close of Period	$ 266,758
Accumulated Depreciation	$ 189,487
Depreciable Lives	30 years
Fiber
Real Estate And Accumulated Depreciation [Line Items]
Gross Amount Carried at Close of Period	$ 2,776,576
Accumulated Depreciation	$ 1,326,936
Depreciable Lives	30 years
Equipment | Minimum
Real Estate And Accumulated Depreciation [Line Items]
Depreciable Lives	5 years
Equipment | Maximum
Real Estate And Accumulated Depreciation [Line Items]
Depreciable Lives	7 years
Copper
Real Estate And Accumulated Depreciation [Line Items]
Gross Amount Carried at Close of Period	$ 3,850,988
Accumulated Depreciation	$ 3,432,894
Depreciable Lives	20 years
Conduit
Real Estate And Accumulated Depreciation [Line Items]
Gross Amount Carried at Close of Period	$ 89,773
Accumulated Depreciation	$ 65,319
Depreciable Lives	30 years
Towers
Real Estate And Accumulated Depreciation [Line Items]
Gross Amount Carried at Close of Period	$ 1,397
Accumulated Depreciation	$ 813
Depreciable Lives	20 years
Finance Lease Assets
Real Estate And Accumulated Depreciation [Line Items]
Gross Amount Carried at Close of Period	$ 25,511
Accumulated Depreciation	2,771
Other assets
Real Estate And Accumulated Depreciation [Line Items]
Gross Amount Carried at Close of Period	10,425
Accumulated Depreciation	$ 3,154
Other assets | Minimum
Real Estate And Accumulated Depreciation [Line Items]
Depreciable Lives	15 years
Other assets | Maximum
Real Estate And Accumulated Depreciation [Line Items]
Depreciable Lives	20 years
Construction in progress
Real Estate And Accumulated Depreciation [Line Items]
Gross Amount Carried at Close of Period	$ 4,397