| Document and Entity Information | Sep. 20, 2019 |
| Document And Entity Information [Line Items] | |
| Amendment Flag | false |
| Entity Central Index Key | 0000732717 |
| Document Type | 8-K |
| Document Period End Date | Sep. 20, 2019 |
| Entity Registrant Name | AT&T INC. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-08610 |
| 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 |
| Floating Rate Att Inc . Global Notes Due August 320202 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Floating Rate AT&T Inc. Global Notes due August 3, 2020 |
| Trading Symbol | T 20C |
| Security Exchange Name | NYSE |
| M 1.875 Att Inc . Global Notes Due December 420206 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.875% AT&T Inc. Global Notes due December 4, 2020 |
| Trading Symbol | T 20 |
| Security Exchange Name | NYSE |
| M 2.65 Att Inc . Global Notes Due December 1720211 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 2.65% AT&T Inc. Global Notes due December 17, 2021 |
| Trading Symbol | T 21B |
| Security Exchange Name | NYSE |
| M 1.45 Att Inc . Global Notes Due June 120229 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.45% AT&T Inc. Global Notes due June 1, 2022 |
| Trading Symbol | T 22B |
| Security Exchange Name | NYSE |
| M 2.50 Att Inc . Global Notes Due March 15202311 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 2.50% AT&T Inc. Global Notes due March 15, 2023 |
| Trading Symbol | T 23 |
| Security Exchange Name | NYSE |
| Floating Rate Att Inc . Global Notes Due September 520232 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Floating Rate AT&T Inc. Global Notes due September 5, 2023 |
| Trading Symbol | T 23D |
| Security Exchange Name | NYSE |
| M 1.05 Att Inc . Global Notes Due September 52023 Member 18 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.05% AT&T Inc. Global Notes due September 5, 2023 |
| Trading Symbol | T 23E |
| Security Exchange Name | NYSE |
| M 1.950 Att Inc . Global Notes Due September 15202310 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.950% AT&T Inc. Global Notes due September 15, 2023 |
| Trading Symbol | T 23F |
| Security Exchange Name | NYSE |
| M 1.30 Att Inc . Global Notes Due September 5202312 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.30% AT&T Inc. Global Notes due September 5, 2023 |
| Trading Symbol | T 23A |
| 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 | T 23C |
| 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 | T 24A |
| Security Exchange Name | NYSE |
| M 3.50 Att Inc . Global Notes Due December 1720252 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 3.50% AT&T Inc. Global Notes due December 17, 2025 |
| Trading Symbol | T 25 |
| Security Exchange Name | NYSE |
| M 0.250 Att Inc . Global Notes Due March 42026 Member 21 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 0.250% AT&T Inc. Global Notes due March 4, 2026 |
| Trading Symbol | T 26E |
| Security Exchange Name | NYSE |
| M 1.80 Att Inc . Global Notes Due September 5202613 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.80% AT&T Inc. Global Notes due September 5, 2026 |
| Trading Symbol | T 26D |
| Security Exchange Name | NYSE |
| M 2.90 Att Inc . Global Notes Due December 420263 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 2.90% AT&T Inc. Global Notes due December 4, 2026 |
| Trading Symbol | T 26A |
| Security Exchange Name | NYSE |
| M 2.35 Att Inc . Global Notes Due September 5202914 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 2.35% AT&T Inc. Global Notes due September 5, 2029 |
| Trading Symbol | T 29D |
| Security Exchange Name | NYSE |
| M 4.375 Att Inc . Global Notes Due September 14202915 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 4.375% AT&T Inc. Global Notes due September 14, 2029 |
| Trading Symbol | T 29B |
| Security Exchange Name | NYSE |
| M 2.60 Att Inc . Global Notes Due December 1720294 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 2.60% AT&T Inc. Global Notes due December 17, 2029 |
| Trading Symbol | T 29A |
| Security Exchange Name | NYSE |
| M 0.800 Att Inc . Global Notes Due March 4203019 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 0.800% AT&T Inc. Global Notes due March 4, 2030 |
| Trading Symbol | T 30B |
| Security Exchange Name | NYSE |
| M 3.55 Att Inc . Global Notes Due December 1720325 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 3.55% AT&T Inc. Global Notes due December 17, 2032 |
| Trading Symbol | T 32 |
| 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 | T 33 |
| 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 | T 34 |
| 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 | T 35 |
| Security Exchange Name | NYSE |
| M 3.15 Att Inc . Global Notes Due September 4203616 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 3.15% AT&T Inc. Global Notes due September 4, 2036 |
| Trading Symbol | T 36A |
| Security Exchange Name | NYSE |
| M 1.800 Att Inc . Global Notes Due September 14203917 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.800% AT&T Inc. Global Notes due September 14, 2039 |
| Trading Symbol | T 39B |
| 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 | T 40 |
| Security Exchange Name | NYSE |
| M 4.25 Att Inc . Global Notes Due June 120437 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 4.25% AT&T Inc. Global Notes due June 1, 2043 |
| Trading Symbol | T 43 |
| Security Exchange Name | NYSE |
| M 4.875 Att Inc . Global Notes Due June 120448 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 4.875% AT&T Inc. Global Notes due June 1, 2044 |
| Trading Symbol | T 44 |
| 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 |
| M 5.625 Att Inc . Global Notes Due August 1206720 [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 |
