{ "instance": { "d176202d8k.htm": { "axisCustom": 0, "axisStandard": 1, "contextCount": 34, "dts": { "definitionLink": { "local": [ "t-20210517_def.xml" ], "remote": [ "http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-eedm-def-2019-01-31.xml", "http://xbrl.fasb.org/srt/2019/elts/srt-eedm1-def-2019-01-31.xml" ] }, "inline": { "local": [ "d176202d8k.htm" ] }, "labelLink": { "local": [ "t-20210517_lab.xml" ], "remote": [ "https://xbrl.sec.gov/dei/2019/dei-doc-2019-01-31.xml" ] }, "presentationLink": { "local": [ "t-20210517_pre.xml" ] }, "referenceLink": { "remote": [ "https://xbrl.sec.gov/dei/2019/dei-ref-2019-01-31.xml" ] }, "schema": { "local": [ "t-20210517.xsd" ], "remote": [ "http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd", "http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd", "http://www.xbrl.org/2003/xl-2003-12-31.xsd", "http://www.xbrl.org/2003/xlink-2003-12-31.xsd", "https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd", "http://www.xbrl.org/2005/xbrldt-2005.xsd", "http://www.xbrl.org/dtr/type/nonNumeric-2009-12-16.xsd", "http://www.xbrl.org/dtr/type/numeric-2009-12-16.xsd", "http://xbrl.sec.gov/sic/2011/sic-2011-01-31.xsd", "https://xbrl.sec.gov/naics/2017/naics-2017-01-31.xsd", "http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd", "http://xbrl.fasb.org/us-gaap/2019/elts/us-roles-2019-01-31.xsd", "http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd", "http://www.xbrl.org/2006/ref-2006-02-27.xsd", "http://xbrl.fasb.org/srt/2019/elts/srt-types-2019-01-31.xsd", "http://xbrl.fasb.org/srt/2019/elts/srt-roles-2019-01-31.xsd", "https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd", "http://xbrl.fasb.org/us-gaap/2019/elts/us-types-2019-01-31.xsd", "http://www.xbrl.org/lrr/role/deprecated-2009-12-16.xsd" ] } }, "elementCount": 60, "entityCount": 1, "hidden": { "http://xbrl.sec.gov/dei/2019-01-31": 2, "total": 2 }, "keyCustom": 0, "keyStandard": 95, "memberCustom": 30, "memberStandard": 3, "nsprefix": "t", "nsuri": "http://att.com/20210517", "report": { "R1": { "firstAnchor": { "ancestors": [ "span", "p", "div", "div", "body", "html" ], "baseRef": "d176202d8k.htm", "contextRef": "duration_2021-05-17_to_2021-05-17", "decimals": null, "first": true, "lang": "en-US", "name": "dei:DocumentType", "reportCount": 1, "unique": true, "unitRef": null, "xsiNil": "false" }, "groupType": "document", "isDefault": "true", "longName": "100000 - Document - Document and Entity Information", "role": "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation", "shortName": "Document and Entity Information", "subGroupType": "", "uniqueAnchor": { "ancestors": [ "span", "p", "div", "div", "body", "html" ], "baseRef": "d176202d8k.htm", "contextRef": "duration_2021-05-17_to_2021-05-17", "decimals": null, "first": true, "lang": "en-US", "name": "dei:DocumentType", "reportCount": 1, "unique": true, "unitRef": null, "xsiNil": "false" } } }, "segmentCount": 33, "tag": { "dei_AmendmentFlag": { "auth_ref": [], "lang": { "en-us": { "role": { "documentation": "Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.", "label": "Amendment Flag", "terseLabel": "Amendment Flag" } } }, "localname": "AmendmentFlag", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "booleanItemType" }, "dei_CityAreaCode": { "auth_ref": [], "lang": { "en-us": { "role": { "documentation": "Area code of city", "label": "City Area Code", "terseLabel": "City Area Code" } } }, "localname": "CityAreaCode", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "normalizedStringItemType" }, "dei_CoverAbstract": { "auth_ref": [], "lang": { "en-us": { "role": { "documentation": "Cover page.", "label": "Cover [Abstract]", "terseLabel": "Cover [Abstract]" } } }, "localname": "CoverAbstract", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "xbrltype": "stringItemType" }, "dei_DocumentPeriodEndDate": { "auth_ref": [], "lang": { "en-us": { "role": { "documentation": "The end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements containing historical data, it is the date up through which that historical data is presented. If there is no historical data in the report, use the filing date. The format of the date is CCYY-MM-DD.", "label": "Document Period End Date", "terseLabel": "Document Period End Date" } } }, "localname": "DocumentPeriodEndDate", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "dateItemType" }, "dei_DocumentType": { "auth_ref": [], "lang": { "en-us": { "role": { "documentation": "The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.", "label": "Document Type", "terseLabel": "Document Type" } } }, "localname": "DocumentType", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "submissionTypeItemType" }, "dei_EntityAddressAddressLine1": { "auth_ref": [], "lang": { "en-us": { "role": { "documentation": "Address Line 1 such as Attn, Building Name, Street Name", "label": "Entity Address, Address Line One", "terseLabel": "Entity Address, Address Line One" } } }, "localname": "EntityAddressAddressLine1", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "normalizedStringItemType" }, "dei_EntityAddressCityOrTown": { "auth_ref": [], "lang": { "en-us": { "role": { "documentation": "Name of the City or Town", "label": "Entity Address, City or Town", "terseLabel": "Entity Address, City or Town" } } }, "localname": "EntityAddressCityOrTown", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "normalizedStringItemType" }, "dei_EntityAddressPostalZipCode": { "auth_ref": [], "lang": { "en-us": { "role": { "documentation": "Code for the postal or zip code", "label": "Entity Address, Postal Zip Code", "terseLabel": "Entity Address, Postal Zip Code" } } }, "localname": "EntityAddressPostalZipCode", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "normalizedStringItemType" }, "dei_EntityAddressStateOrProvince": { "auth_ref": [], "lang": { "en-us": { "role": { "documentation": "Name of the state or province.", "label": "Entity Address, State or Province", "terseLabel": "Entity Address, State or Province" } } }, "localname": "EntityAddressStateOrProvince", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "stateOrProvinceItemType" }, "dei_EntityCentralIndexKey": { "auth_ref": [ "r5" ], "lang": { "en-us": { "role": { "documentation": "A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.", "label": "Entity Central Index Key", "terseLabel": "Entity Central Index Key" } } }, "localname": "EntityCentralIndexKey", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "centralIndexKeyItemType" }, "dei_EntityEmergingGrowthCompany": { "auth_ref": [ "r5" ], "lang": { "en-us": { "role": { "documentation": "Indicate if registrant meets the emerging growth company criteria.", "label": "Entity Emerging Growth Company", "terseLabel": "Entity Emerging Growth Company" } } }, "localname": "EntityEmergingGrowthCompany", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "booleanItemType" }, "dei_EntityFileNumber": { "auth_ref": [], "lang": { "en-us": { "role": { "documentation": "Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.", "label": "Entity File Number", "terseLabel": "Entity File Number" } } }, "localname": "EntityFileNumber", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "fileNumberItemType" }, "dei_EntityIncorporationStateCountryCode": { "auth_ref": [], "lang": { "en-us": { "role": { "documentation": "Two-character EDGAR code representing the state or country of incorporation.", "label": "Entity Incorporation State Country Code", "terseLabel": "Entity Incorporation State Country Code" } } }, "localname": "EntityIncorporationStateCountryCode", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "edgarStateCountryItemType" }, "dei_EntityRegistrantName": { "auth_ref": [ "r5" ], "lang": { "en-us": { "role": { "documentation": "The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.", "label": "Entity Registrant Name", "terseLabel": "Entity Registrant Name" } } }, "localname": "EntityRegistrantName", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "normalizedStringItemType" }, "dei_EntityTaxIdentificationNumber": { "auth_ref": [ "r5" ], "lang": { "en-us": { "role": { "documentation": "The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.", "label": "Entity Tax Identification Number", "terseLabel": "Entity Tax Identification Number" } } }, "localname": "EntityTaxIdentificationNumber", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "employerIdItemType" }, "dei_LocalPhoneNumber": { "auth_ref": [], "lang": { "en-us": { "role": { "documentation": "Local phone number for entity.", "label": "Local Phone Number", "terseLabel": "Local Phone Number" } } }, "localname": "LocalPhoneNumber", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "normalizedStringItemType" }, "dei_PreCommencementIssuerTenderOffer": { "auth_ref": [ "r2" ], "lang": { "en-us": { "role": { "documentation": "Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act.", "label": "Pre Commencement Issuer Tender Offer", "terseLabel": "Pre Commencement Issuer Tender Offer" } } }, "localname": "PreCommencementIssuerTenderOffer", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "booleanItemType" }, "dei_PreCommencementTenderOffer": { "auth_ref": [ "r3" ], "lang": { "en-us": { "role": { "documentation": "Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act.", "label": "Pre Commencement Tender Offer", "terseLabel": "Pre Commencement Tender Offer" } } }, "localname": "PreCommencementTenderOffer", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "booleanItemType" }, "dei_Security12bTitle": { "auth_ref": [ "r0" ], "lang": { "en-us": { "role": { "documentation": "Title of a 12(b) registered security.", "label": "Security 12b Title", "terseLabel": "Security 12b Title" } } }, "localname": "Security12bTitle", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "securityTitleItemType" }, "dei_SecurityExchangeName": { "auth_ref": [ "r1" ], "lang": { "en-us": { "role": { "documentation": "Name of the Exchange on which a security is registered.", "label": "Security Exchange Name", "terseLabel": "Security Exchange Name" } } }, "localname": "SecurityExchangeName", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "edgarExchangeCodeItemType" }, "dei_SolicitingMaterial": { "auth_ref": [ "r4" ], "lang": { "en-us": { "role": { "documentation": "Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as soliciting material pursuant to Rule 14a-12 under the Exchange Act.", "label": "Soliciting Material", "terseLabel": "Soliciting Material" } } }, "localname": "SolicitingMaterial", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "booleanItemType" }, "dei_TradingSymbol": { "auth_ref": [], "lang": { "en-us": { "role": { "documentation": "Trading symbol of an instrument as listed on an exchange.", "label": "Trading Symbol", "terseLabel": "Trading Symbol" } } }, "localname": "TradingSymbol", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "tradingSymbolItemType" }, "dei_WrittenCommunications": { "auth_ref": [ "r6" ], "lang": { "en-us": { "role": { "documentation": "Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as written communications pursuant to Rule 425 under the Securities Act.", "label": "Written Communications", "terseLabel": "Written Communications" } } }, "localname": "WrittenCommunications", "nsuri": "http://xbrl.sec.gov/dei/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "booleanItemType" }, "t_ATTInc0250GlobalNotesDueMarch42026Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 0250 Global Notes Due March 42026 [Member]", "terseLabel": "ATT Inc 0250 Global Notes Due March 42026 [Member]" } } }, "localname": "ATTInc0250GlobalNotesDueMarch42026Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc0800GlobalNotesDueMarch42030Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 0800 Global Notes Due March 42030 [Member]", "terseLabel": "ATT Inc 0800 Global Notes Due March 42030 [Member]" } } }, "localname": "ATTInc0800GlobalNotesDueMarch42030Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc1050GlobalNotesDueSeptember52023Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 1050 Global Notes Due September 52023 [Member]", "terseLabel": "ATT Inc 1050 Global Notes Due September 52023 [Member]" } } }, "localname": "ATTInc1050GlobalNotesDueSeptember52023Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc1300GlobalNotesDueSeptember52023Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 1300 Global Notes Due September 52023 [Member]", "terseLabel": "ATT Inc 1300 Global Notes Due September 52023 [Member]" } } }, "localname": "ATTInc1300GlobalNotesDueSeptember52023Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc1450GlobalNotesDueJune12022Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 1450 Global Notes Due June 12022 [Member]", "terseLabel": "ATT Inc 1450 Global Notes Due June 12022 [Member]" } } }, "localname": "ATTInc1450GlobalNotesDueJune12022Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc1950GlobalNotesDueSeptember152023Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 1950 Global Notes Due September 152023 [Member]", "terseLabel": "ATT Inc 1950 Global Notes Due September 152023 [Member]" } } }, "localname": "ATTInc1950GlobalNotesDueSeptember152023Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc2350GlobalNotesDueSeptember52029Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 2350 Global Notes Due September 52029 [Member]", "terseLabel": "ATT Inc 2350 Global Notes Due September 52029 [Member]" } } }, "localname": "ATTInc2350GlobalNotesDueSeptember52029Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc2400GlobalNotesDueMarch152024Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 2400 Global Notes Due March 152024 [Member]", "terseLabel": "ATT Inc 2400 Global Notes Due March 152024 [Member]" } } }, "localname": "ATTInc2400GlobalNotesDueMarch152024Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc2450GlobalNotesDueMarch152035Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 2450 Global Notes Due March 152035 [Member]", "terseLabel": "ATT Inc 2450 Global Notes Due March 152035 [Member]" } } }, "localname": "ATTInc2450GlobalNotesDueMarch152035Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc2500GlobalNotesDueMarch152023Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 2500 Global Notes Due March 152023 [Member]", "terseLabel": "ATT Inc 2500 Global Notes Due March 152023 [Member]" } } }, "localname": "ATTInc2500GlobalNotesDueMarch152023Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc2600GlobalNotesDueDecember172029Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 2600 Global Notes Due December 172029 [Member]", "terseLabel": "ATT Inc 2600 Global Notes Due December 172029 [Member]" } } }, "localname": "ATTInc2600GlobalNotesDueDecember172029Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc2650GlobalNotesDueDecember172021Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 2650 Global Notes Due December 172021 [Member]", "terseLabel": "ATT Inc 2650 Global Notes Due December 172021 [Member]" } } }, "localname": "ATTInc2650GlobalNotesDueDecember172021Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc2750GlobalNotesDueMay192023Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 2750 Global Notes Due May 192023 [Member]", "terseLabel": "ATT Inc 2750 Global Notes Due May 192023 [Member]" } } }, "localname": "ATTInc2750GlobalNotesDueMay192023Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc2900PercentGlobalNotesDueDecember42026Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 2900 Percent Global Notes Due December 42026 [Member]", "terseLabel": "ATT Inc 2900 Percent Global Notes Due December 42026 [Member]" } } }, "localname": "ATTInc2900PercentGlobalNotesDueDecember42026Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc3150GlobalNotesDueSeptember42036Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 3150 Global Notes Due September 42036 [Member]", "terseLabel": "ATT Inc 3150 Global Notes Due September 42036 [Member]" } } }, "localname": "ATTInc3150GlobalNotesDueSeptember42036Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc3375GlobalNotesDueMarch152034Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 3375 Global Notes Due March 152034 [Member]", "terseLabel": "ATT Inc 3375 Global Notes Due March 152034 [Member]" } } }, "localname": "ATTInc3375GlobalNotesDueMarch152034Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc3500GlobalNotesDueDecember172025Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 3500 Global Notes Due December 172025 [Member]", "terseLabel": "ATT Inc 3500 Global Notes Due December 172025 [Member]" } } }, "localname": "ATTInc3500GlobalNotesDueDecember172025Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc3550GlobalNotesDueDecember172032Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 3550 Global Notes Due December 172032 [Member]", "terseLabel": "ATT Inc 3550 Global Notes Due December 172032 [Member]" } } }, "localname": "ATTInc3550GlobalNotesDueDecember172032Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc4250GlobalNotesDueJune12043Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 4250 Global Notes Due June 12043 [Member]", "terseLabel": "ATT Inc 4250 Global Notes Due June 12043 [Member]" } } }, "localname": "ATTInc4250GlobalNotesDueJune12043Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc4375GlobalNotesDueSeptember142029Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 4375 Global Notes Due September 142029 [Member]", "terseLabel": "ATT Inc 4375 Global Notes Due September 142029 [Member]" } } }, "localname": "ATTInc4375GlobalNotesDueSeptember142029Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc4875GlobalNotesDueJune12044Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 4875 Global Notes Due June 12044 [Member]", "terseLabel": "ATT Inc 4875 Global Notes Due June 12044 [Member]" } } }, "localname": "ATTInc4875GlobalNotesDueJune12044Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc5200GlobalNotesDueNovember182033Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 5200 Global Notes Due November 182033 [Member]", "terseLabel": "ATT Inc 5200 Global Notes Due November 182033 [Member]" } } }, "localname": "ATTInc5200GlobalNotesDueNovember182033Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc5350GlobalNotesDueNovember12066Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 5350 Global Notes Due November 12066 [Member]", "terseLabel": "ATT Inc 5350 Global Notes Due November 12066 [Member]" } } }, "localname": "ATTInc5350GlobalNotesDueNovember12066Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc5625GlobalNotesDueAugust12067Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 5625 Global Notes Due August 12067 [Member]", "terseLabel": "ATT Inc 5625 Global Notes Due August 12067 [Member]" } } }, "localname": "ATTInc5625GlobalNotesDueAugust12067Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTInc7000GlobalNotesDueApril302040Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc 7000 Global Notes Due April 302040 [Member]", "terseLabel": "ATT Inc 7000 Global Notes Due April 302040 [Member]" } } }, "localname": "ATTInc7000GlobalNotesDueApril302040Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_ATTIncFloatingRateDueSeptember52023Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "ATT Inc Floating Rate Due September 52023 [Member]", "terseLabel": "ATT Inc Floating Rate Due September 52023 [Member]" } } }, "localname": "ATTIncFloatingRateDueSeptember52023Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_AttInc.1.800GlobalNotesDueSeptember1420391Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "Att Inc .1.800 Global Notes Due September 1420391 [Member]", "terseLabel": "Att Inc .1.800 Global Notes Due September 1420391 [Member]" } } }, "localname": "AttInc.1.800GlobalNotesDueSeptember1420391Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_AttInc.1.800GlobalNotesDueSeptember520262Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "Att Inc .1.800 Global Notes Due September 520262 [Member]", "terseLabel": "Att Inc .1.800 Global Notes Due September 520262 [Member]" } } }, "localname": "AttInc.1.800GlobalNotesDueSeptember520262Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_AttInc4000GlobalNotesDueJune12049Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "Att Inc 4000 Global Notes Due June 12049 [Member]", "terseLabel": "Att Inc 4000 Global Notes Due June 12049 [Member]" } } }, "localname": "AttInc4000GlobalNotesDueJune12049Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_AttInc4250GlobalNotesDueMarch12050Member": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "Att Inc 4250 Global Notes Due March 12050 [Member]", "terseLabel": "Att Inc 4250 Global Notes Due March 12050 [Member]" } } }, "localname": "AttInc4250GlobalNotesDueMarch12050Member", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "t_DocumentAndEntityInformationLineItems": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "Document And Entity Information [Line Items]", "terseLabel": "Document And Entity Information [Line Items]" } } }, "localname": "DocumentAndEntityInformationLineItems", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "stringItemType" }, "t_DocumentAndEntityInformationTable": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "Document And Entity Information [Table]", "terseLabel": "Document And Entity Information [Table]" } } }, "localname": "DocumentAndEntityInformationTable", "nsuri": "http://att.com/20210517", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "stringItemType" }, "us-gaap_ClassOfStockDomain": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "Class of Stock [Domain]", "terseLabel": "Class of Stock [Domain]" } } }, "localname": "ClassOfStockDomain", "nsuri": "http://fasb.org/us-gaap/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "us-gaap_CommonStockMember": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "Common Stock [Member]", "terseLabel": "Common Stock [Member]" } } }, "localname": "CommonStockMember", "nsuri": "http://fasb.org/us-gaap/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "us-gaap_SeriesAPreferredStockMember": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "Series A Preferred Stock [Member]", "terseLabel": "Series A Preferred Stock [Member]" } } }, "localname": "SeriesAPreferredStockMember", "nsuri": "http://fasb.org/us-gaap/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "us-gaap_SeriesCPreferredStockMember": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "Series C Preferred Stock [Member]", "terseLabel": "Series C Preferred Stock [Member]" } } }, "localname": "SeriesCPreferredStockMember", "nsuri": "http://fasb.org/us-gaap/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "domainItemType" }, "us-gaap_StatementClassOfStockAxis": { "auth_ref": [], "lang": { "en-us": { "role": { "label": "Class of Stock [Axis]", "terseLabel": "Class of Stock [Axis]" } } }, "localname": "StatementClassOfStockAxis", "nsuri": "http://fasb.org/us-gaap/2019-01-31", "presentation": [ "http://att.com//20210517/taxonomy/role/DocumentDocumentAndEntityInformation" ], "xbrltype": "stringItemType" } }, "unitCount": 0 } }, "std_ref": { "r0": { "Name": "Exchange Act", "Number": "240", "Publisher": "SEC", "Section": "12", "Subsection": "b" }, "r1": { "Name": "Exchange Act", "Number": "240", "Publisher": "SEC", "Section": "12", "Subsection": "d1-1" }, "r2": { "Name": "Exchange Act", "Number": "240", "Publisher": "SEC", "Section": "13e", "Subsection": "4c" }, "r3": { "Name": "Exchange Act", "Number": "240", "Publisher": "SEC", "Section": "14d", "Subsection": "2b" }, "r4": { "Name": "Exchange Act", "Number": "240", "Publisher": "SEC", "Section": "14a", "Subsection": "12" }, "r5": { "Name": "Regulation 12B", "Number": "240", "Publisher": "SEC", "Section": "12", "Subsection": "b-2" }, "r6": { "Name": "Securities Act", "Number": "230", "Publisher": "SEC", "Section": "425" } }, "version": "2.1" }