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 | |