v3.20.4

Acquisitions, Dispositions And Other Adjustments (Spectrum Auctions Narrative) (Details) - USD ($) $ in Millions | 1 Months Ended | 3 Months Ended | 6 Months Ended
--- | --- | --- | ---
Jun. 30, 2020 | Dec. 31, 2019 | Jun. 30, 2020 | Mar. 31, 2020 | Jun. 30, 2020
Licensing Agreements |  |  |  |  |
Indefinite-lived Intangible Assets [Line Items] |  |  |  |  |
Payments to acquire intangible assets | $ 2,379 |  | $ 949 |  | $ 1,186
24 GHz Licenses |  |  |  |  |
Indefinite-lived Intangible Assets [Line Items] |  |  |  |  |
Payments to acquire intangible assets |  | $ 982 |  |  |
FiberTower Corporation | 39 GHz Licenses |  |  |  |  |
Indefinite-lived Intangible Assets [Line Items] |  |  |  |  |
Book value of indefinite-lived intangible assets |  |  |  | $ 300 |
Gain on disposition of intangible asset |  |  |  | $ 900 |
Value of consideration received in a noncash transaction |  |  |  |  | $ 1,200

X
- Definition Amount of gain (loss) on sale or disposal of intangible assets. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585 + Details
Name: | us-gaap_GainLossOnDispositionOfIntangibleAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value portion of assets, excluding financial assets and goodwill, that lack physical substance, having a projected indefinite period of benefit. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
Name: | us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwillFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The value of the noncash (or part noncash) consideration received in a transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of a transaction not resulting in cash receipts or cash payments in the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4313-108586 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586 + Details
Name: | us-gaap_OtherSignificantNoncashTransactionValueOfConsiderationReceived1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The cash outflow to acquire asset without physical form usually arising from contractual or other legal rights, excluding goodwill. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3213-108585 + Details
Name: | us-gaap_PaymentsToAcquireIntangibleAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_LicensingAgreementsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis=t_A24GHzLicensesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=t_FibertowerCorporationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis=t_Ghz39LicensesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |