Leases - Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2021	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets		$ 110,232	$ 104,271
Other current liabilities		$ 54,940	56,856
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]		Deferred Long-term Liability Charges
Operating lease liabilities		$ 69,660	63,526
Total		$ 124,600	120,382
Operating Lease, Liability, Statement of Financial Position [Extensible List]		us-gaap:OperatingLeaseLiabilityNoncurrent us-gaap:AccountsPayableCurrent
Property and equipment, gross		$ 7,027,039	6,965,949
Accumulated depreciation		(4,846,766)	(4,783,616)
Property and equipment, net		2,180,273	2,182,333
Other current liabilities		53,564	58,379
Other long-term liabilities		90,782	103,795
Total		$ 144,346	$ 162,174
Operating Lease, Weighted Average Remaining Lease Term		2 years 9 months 18 days	2 years 9 months 18 days
Finance Lease, Weighted Average Remaining Lease Term		2 years 10 months 24 days	3 years 1 month 6 days
Operating Lease, Weighted Average Discount Rate, Percent		4.10%	4.20%
Finance Lease, Weighted Average Discount Rate, Percent		10.50%	10.40%
Asset Impairment Charges	$ 356,418
Property and equipment [Member]
Lessee, Lease, Description [Line Items]
Property and equipment, gross		$ 889,708	$ 889,708
Accumulated depreciation		(772,121)	(754,292)
Property and equipment, net		$ 117,587	$ 135,416
NBIoT capitalized costs
Lessee, Lease, Description [Line Items]
Asset Impairment Charges	253,000
NBIoT capitalized costs | Operating lease assets
Lessee, Lease, Description [Line Items]
Asset Impairment Charges	$ 26,556