| Document and Entity Information | Aug. 26, 2019 |
| Document And Entity Information [Line Items] | |
| Amendment Flag | false |
| Entity Central Index Key | 0000732717 |
| Document Type | 8-K |
| Document Period End Date | Aug. 26, 2019 |
| Entity Registrant Name | AT&T INC. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 1-8610 |
| Entity Tax Identification Number | 43-1301883 |
| Entity Address, Address Line One | 208 S. Akard St. |
| Entity Address, City or Town | Dallas |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 75202 |
| City Area Code | (210) |
| Local Phone Number | 821-4105 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Common Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Common Shares (Par Value $1.00 Per Share) |
| Trading Symbol | T |
| Security Exchange Name | NYSE |
| AT And T Incorporated Floating Rate Due August 32020 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Floating Rate AT&T Inc. Global Notes due August 3, 2020 |
| Trading Symbol | T20C |
| Security Exchange Name | NYSE |
| AT And T Incorporated One Point Eight Seven Five Percent Global Notes Due December 42020 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.875% AT&T Inc. Global Notes due December 4, 2020 |
| Trading Symbol | T20 |
| Security Exchange Name | NYSE |
| AT And T Incorporate Two Point Six Five Percentd Global Notes Due December 172021 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 2.65% AT&T Inc. Global Notes due December 17, 2021 |
| Trading Symbol | T21B |
| Security Exchange Name | NYSE |
| AT And T Incorporated One Point Four Five Percent Global Notes Due June 12022 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.45% AT&T Inc. Global Notes due June 1, 2022 |
| Trading Symbol | T22B |
| Security Exchange Name | NYSE |
| AT And T Incorporated Two Point Five Zero Percent Global Notes Due March 152023 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 2.50% AT&T Inc. Global Notes due March 15, 2023 |
| Trading Symbol | T23 |
| Security Exchange Name | NYSE |
| AT And T Incorporated Floating Rate Due September 52023 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Floating Rate AT&T Inc. Global Notes due September 5, 2023 |
| Trading Symbol | T23 D |
| Security Exchange Name | NYSE |
| M 1.05 Att Inc . Global Notes Due September 520232 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.05% AT&T Inc. Global Notes due September 5, 2023 |
| Trading Symbol | T23E |
| Security Exchange Name | NYSE |
| AT And T Incorporated One Point Nine Five Percent Global Notes Due September 152023 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.950% AT&T Inc. Global Notes due September 15, 2023 |
| Trading Symbol | T23F |
| Security Exchange Name | NYSE |
| M 1.30 Att Inc . Global Notes Due September 520231 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.30% AT&T Inc. Global Notes due September 5, 2023 |
| Trading Symbol | T23A |
| Security Exchange Name | NYSE |
| AT And T Incorporated Two Point Seven Five Percent Global Notes Due May 192023 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 2.75% AT&T Inc. Global Notes due May 19, 2023 |
| Trading Symbol | T23C |
| Security Exchange Name | NYSE |
| AT And T Incorporated Two Point Four Zero Percent Global Notes Due March 152024 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 2.40% AT&T Inc. Global Notes due March 15, 2024 |
| Trading Symbol | T24A |
| Security Exchange Name | NYSE |
| AT And T Incorporated Three Point Five Zero Percent Global Notes Due December 172025 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 3.50% AT&T Inc. Global Notes due December 17, 2025 |
| Trading Symbol | T25 |
| Security Exchange Name | NYSE |
| AT And T Incorporated One Point Eight Zero Percent Global Notes Due September 52026 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.80% AT&T Inc. Global Notes due September 5, 2026 |
| Trading Symbol | T26D |
| Security Exchange Name | NYSE |
| AT And T Incorporated Two Point Nine Zero Percent Global Notes Due December 42026 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 2.90% AT&T Inc. Global Notes due December 4, 2026 |
| Trading Symbol | T26A |
| Security Exchange Name | NYSE |
| AT And T Incorporated Two Point Three Five Percent Global Notes Due September 52029 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 2.35% AT&T Inc. Global Notes due September 5, 2029 |
| Trading Symbol | T29D |
| Security Exchange Name | NYSE |
| AT And T Incorporated Four Point Three Seven Five Percent Global Notes Due September 142029 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 4.375% AT&T Inc. Global Notes due September 14, 2029 |
| Trading Symbol | T29B |
| Security Exchange Name | NYSE |
| AT And T Incorporated Two Point Six Zero Percent Global Notes Due December 172029 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 2.60% AT&T Inc. Global Notes due December 17, 2029 |
| Trading Symbol | T29A |
| Security Exchange Name | NYSE |
| AT And T Incorporated Three Point Five Five Percent Global Notes Due December 172032 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 3.55% AT&T Inc. Global Notes due December 17, 2032 |
| Trading Symbol | T32 |
| Security Exchange Name | NYSE |
| AT And T Incorporated Five Point Two Zero Percent Global Notes Due November 182033 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 5.20% AT&T Inc. Global Notes due November 18, 2033 |
| Trading Symbol | T33 |
| Security Exchange Name | NYSE |
| AT And T Incorporated Three Point Three Seven Five Percent Global Notes Due March 152034 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 3.375% AT&T Inc. Global Notes due March 15, 2034 |
| Trading Symbol | T34 |
| Security Exchange Name | NYSE |
| AT And T Incorporated Two Point Four Five Percent Global Notes Due March 152035 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 2.45% AT&T Inc. Global Notes due March 15, 2035 |
| Trading Symbol | T35 |
| Security Exchange Name | NYSE |
| AT And T Incorporated Three Point One Five Percent Global Notes Due September 42036 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 3.15% AT&T Inc. Global Notes due September 4, 2036 |
| Trading Symbol | T36A |
| Security Exchange Name | NYSE |
| AT And T Incorporated Seven Point Zero Zero Percent Global Notes Due April 302040 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 7.00% AT&T Inc. Global Notes due April 30, 2040 |
| Trading Symbol | T40 |
| Security Exchange Name | NYSE |
| Four Point Two Five Percent AT And T Incorporated Global Notes Due June 12043 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 4.25% AT&T Inc. Global Notes due June 1, 2043 |
| Trading Symbol | T43 |
| Security Exchange Name | NYSE |
| AT And T Incorporated Four Point Eight Seven Five Percent Global Notes Due June 12044 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 4.875% AT&T Inc. Global Notes due June 1, 2044 |
| Trading Symbol | T44 |
| Security Exchange Name | NYSE |
| AT And T Incorporated Five Point Three Five Percent Global Notes Due November 12066 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 5.35% AT&T Inc. Global Notes due November 1, 2066 |
| Trading Symbol | TBB |
| Security Exchange Name | NYSE |
| AT And T Incorporated Five Point Six Two Five Percent Global Notes Due August 12067 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 5.625% AT&T Inc. Global Notes due August 1, 2067 |
| Trading Symbol | TBC |
| Security Exchange Name | NYSE |
