v3.20.4

Additional Financial Information (Narrative) (Details) employee in Thousands, $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 USD ($) employee | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Jan. 31, 2021 employee
Additional Financial Information [Line Items] |  |  |  |
Percentage of employees represented by CWA, IBEW, or other unions | 37.00% |  |  |
Subsequent Event |  |  |  |
Additional Financial Information [Line Items] |  |  |  |
Approximate number of persons employed at a point in time |  |  |  | 230
Contract Covering Employees in 36 States and District of Columbia | Communications | Mobility |  |  |  |
Additional Financial Information [Line Items] |  |  |  |
Number of employees under contracts where union may call a work stoppage | 14 |  |  |
Contract Covering Employees in 9 Southeast States | Communications | Mobility |  |  |  |
Additional Financial Information [Line Items] |  |  |  |
Number of employees under contracts where union may call a work stoppage | 10 |  |  |
Vendor Financing Program |  |  |  |
Additional Financial Information [Line Items] |  |  |  |
Noncash investing activities | $ | $ 4,664 | $ 2,632 | $ 2,162 |

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