v3.20.4

Contingent Liabilities (Narrative) (Details) $ in Millions | Dec. 31, 2020 USD ($)
--- | ---
Commitments and Contingencies Disclosure [Abstract] |
Contractual purchase obligations for 2021 | $ 20,274
Contractual purchase obligations for 2022 and 2023 | 21,275
Contractual purchase obligations for 2024 and 2025 | 11,142
Contractual purchase obligations for total years thereafter | $ 17,919

X
- Definition The remaining amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation on the fourth and fifth anniversary of the balance sheet date. + References No definition available. + Details
Name: | t_UnrecordedUnconditionalPurchaseObligationDueWithinFourToFiveYears
Namespace Prefix: | t_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The remaining amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation on the second and third anniversary of the balance sheet date. + References No definition available. + Details
Name: | t_UnrecordedUnconditionalPurchaseObligationDueWithinTwoToThreeYears
Namespace Prefix: | t_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- References No definition available. + Details
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Balance Type: | na
Period Type: | duration

X
- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=77896938&loc=d3e25336-109308 + Details
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Balance Type: | credit
Period Type: | instant

X
- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=77896938&loc=d3e25336-109308 + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant