Leases - Schedule of Underlying Assets under Operating Leases (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Lessor Lease Description [Line Items]
Underlying assets under operating leases, gross	$ 7,821,421	$ 7,608,978
Less: accumulated depreciation	(5,319,033)	(5,222,731)
Underlying assets under operating leases, net	2,502,388	2,386,247
Land
Lessor Lease Description [Line Items]
Underlying assets under operating leases, gross	26,596	26,596
Building and Improvements
Lessor Lease Description [Line Items]
Underlying assets under operating leases, gross	340,096	335,495
Poles
Lessor Lease Description [Line Items]
Underlying assets under operating leases, gross	273,934	266,758
Fiber
Lessor Lease Description [Line Items]
Underlying assets under operating leases, gross	3,147,976	2,994,465
Equipment
Lessor Lease Description [Line Items]
Underlying assets under operating leases, gross	428	421
Copper
Lessor Lease Description [Line Items]
Underlying assets under operating leases, gross	3,902,265	3,850,988
Conduit
Lessor Lease Description [Line Items]
Underlying assets under operating leases, gross	89,960	89,773
Tower assets
Lessor Lease Description [Line Items]
Underlying assets under operating leases, gross	1,397	1,397
Finance Lease Assets
Lessor Lease Description [Line Items]
Underlying assets under operating leases, gross	28,126	32,660
Other assets
Lessor Lease Description [Line Items]
Underlying assets under operating leases, gross	$ 10,643	$ 10,425