v3.20.4

Debt (Financing Activities) (Narrative) (Details) - USD ($) | 1 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2020 | Sep. 30, 2020 | Aug. 31, 2020 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Debt Instrument [Line Items] |  |  |  |  |  |
Net proceeds received from issuance of long-term debt |  |  |  | $ 31,988,000,000 | $ 17,039,000,000 | $ 41,875,000,000
Debt Instrument - principal/face amount | $ 32,241,000,000 |  |  | $ 32,241,000,000 |  |
Weighted maturity period |  |  |  | 20 years |  |
Weighted average coupon |  |  |  | 3.20% |  |
Repayment of long-term debt |  |  |  | $ 39,964,000,000 | $ 27,592,000,000 | $ 52,643,000,000
Weighted-average interest rate | 4.10% |  |  | 4.10% | 4.40% |
Various Notes |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Weighted average coupon |  |  |  | 3.20% |  |
Amount of borrowings repaid / debt exchanged |  |  |  | $ 39,758,000,000 |  |
AT&T Global Notes and Subsidiary Notes due 2021 to 2025 |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Repayment of long-term debt |  |  | $ 11,384,000,000 |  |  |
AT&T and Subsidiary Notes |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Amount of borrowings repaid / debt exchanged |  | $ 17,677,000,000 |  |  |  |
Repayment of long-term debt |  | 1,459,000,000 |  |  |  |
Three New Series of AT&T Global Notes due 2053 to 2059 |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Net proceeds received from issuance of long-term debt |  | $ 21,500,000,000 |  |  |  |
AT&T and Subsidiary Notes due 2026 to 2048 |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Amount of borrowings repaid / debt exchanged | $ 8,280,000,000 |  |  |  |  |
Repayment of long-term debt | 8,000,000 |  |  |  |  |
Two New Series of Global Notes due 2033 to 2057 |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Net proceeds received from issuance of long-term debt | $ 9,678,000,000 |  |  |  |  |
Minimum | AT&T and Subsidiary Notes |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Weighted-average interest rate |  | 4.35% |  |  |  |
Minimum | Three New Series of AT&T Global Notes due 2053 to 2059 |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Weighted-average interest rate |  | 3.50% |  |  |  |
Minimum | AT&T and Subsidiary Notes due 2026 to 2048 |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Weighted-average interest rate | 2.95% |  |  | 2.95% |  |
Minimum | Two New Series of Global Notes due 2033 to 2057 |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Weighted-average interest rate | 2.55% |  |  | 2.55% |  |
Maximum | AT&T and Subsidiary Notes |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Weighted-average interest rate |  | 8.75% |  |  |  |
Maximum | Three New Series of AT&T Global Notes due 2053 to 2059 |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Weighted-average interest rate |  | 3.65% |  |  |  |
Maximum | AT&T and Subsidiary Notes due 2026 to 2048 |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Weighted-average interest rate | 7.125% |  |  | 7.125% |  |
Maximum | Two New Series of Global Notes due 2033 to 2057 |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Weighted-average interest rate | 3.80% |  |  | 3.80% |  |

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