| Document and Entity Information | Dec. 12, 2019 |
| Document And Entity Information [Line Items] | |
| Amendment Flag | false |
| Entity Central Index Key | 0000732717 |
| Document Type | 8-K |
| Document Period End Date | Dec. 12, 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 |
| Series A Preferred Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Depositary Shares, each representing a 1/1000th interest in a share of 5.000% Perpetual preferred Stock, Series A |
| Trading Symbol | T PRA |
| Security Exchange Name | NYSE |
| Att Inc . Floating Rate Global Notes Due August 320202 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. Floating Rate Global Notes due August 3, 2020 |
| Trading Symbol | T 20C |
| Security Exchange Name | NYSE |
| Att Inc .1.875 Global Notes Due December 420206 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 1.875% Global Notes due December 4, 2020 |
| Trading Symbol | T 20 |
| Security Exchange Name | NYSE |
| Att Inc .2.65 Global Notes Due December 1720211 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 2.65% Global Notes due December 17, 2021 |
| Trading Symbol | T 21B |
| Security Exchange Name | NYSE |
| Att Inc .1.45 Global Notes Due June 120229 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 1.45% Global Notes due June 1, 2022 |
| Trading Symbol | T 22B |
| Security Exchange Name | NYSE |
| Att Inc .2.50 Global Notes Due March 152023 Member 15 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 2.50% Global Notes due March 15, 2023 |
| Trading Symbol | T 23 |
| Security Exchange Name | NYSE |
| ATT Inc 275 Global Notes Due May 192023 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 2.75% Global Notes due May 19, 2023 |
| Trading Symbol | T 23C |
| Security Exchange Name | NYSE |
| Att Inc . Floating Rate Global Notes Due September 520231 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. Floating Rate Global Notes due September 5, 2023 |
| Trading Symbol | T 23D |
| Security Exchange Name | NYSE |
| Att Inc .1.05 Global Notes Due September 520231 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 1.05% Global Notes due September 5, 2023 |
| Trading Symbol | T 23E |
| Security Exchange Name | NYSE |
| Att Inc .1.30 Global Notes Due September 52023 Member 22 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 1.30% Global Notes due September 5, 2023 |
| Trading Symbol | T 23A |
| Security Exchange Name | NYSE |
| Att Inc .1.95 Global Notes Due September 15202316 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 1.95% Global Notes due September 15, 2023 |
| Trading Symbol | T 23F |
| Security Exchange Name | NYSE |
| Att Inc .2.40 Global Notes Due March 15202410 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 2.40% Global Notes due March 15, 2024 |
| Trading Symbol | T 24A |
| Security Exchange Name | NYSE |
| Att Inc .3.50 Global Notes Due December 1720252 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 3.50% Global Notes due December 17, 2025 |
| Trading Symbol | T 25 |
| Security Exchange Name | NYSE |
| Att Inc .0.250 Global Notes Due March 4202611 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 0.250% Global Notes due March 4, 2026 |
| Trading Symbol | T 26E |
| Security Exchange Name | NYSE |
| Att Inc .1.80 Global Notes Due September 5202617 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 1.80% Global Notes due September 5, 2026 |
| Trading Symbol | T 26D |
| Security Exchange Name | NYSE |
| Att Inc .2.90 Global Notes Due December 420263 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 2.90% Global Notes due December 4, 2026 |
| Trading Symbol | T 26A |
| Security Exchange Name | NYSE |
| Att Inc .2.35 Global Notes Due September 5202918 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 2.35% Global Notes due September 5, 2029 |
| Trading Symbol | T 29D |
| Security Exchange Name | NYSE |
| Att Inc .4.375 Global Notes Due September 14202919 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 4.375% Global Notes due September 14, 2029 |
| Trading Symbol | T 29B |
| Security Exchange Name | NYSE |
| Att Inc .2.60 Global Notes Due December 1720294 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 2.60% Global Notes due December 17, 2029 |
| Trading Symbol | T 29A |
| Security Exchange Name | NYSE |
| Att Inc .0.800 Global Notes Due March 4203012 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 0.800% Global Notes due March 4, 2030 |
| Trading Symbol | T 30B |
| Security Exchange Name | NYSE |
| Att Inc .3.55 Global Notes Due December 1720325 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 3.55% Global Notes due December 17, 2032 |
| Trading Symbol | T 32 |
| Security Exchange Name | NYSE |
| Att Inc .5.20 Global Notes Due November 182033 Member 24 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 5.20% Global Notes due November 18, 2033 |
| Trading Symbol | T 33 |
| Security Exchange Name | NYSE |
| Att Inc .3.375 Global Notes Due March 1520342 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 3.375% Global Notes due March 15, 2034 |
| Trading Symbol | T 34 |
| Security Exchange Name | NYSE |
| Att Inc .2.45 Global Notes Due March 15203513 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 2.45% Global Notes due March 15, 2035 |
| Trading Symbol | T 35 |
| Security Exchange Name | NYSE |
| Att Inc .3.15 Global Notes Due September 4203620 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 3.15% Global Notes due September 4, 2036 |
| Trading Symbol | T 36A |
| Security Exchange Name | NYSE |
| Att Inc .1.800 Global Notes Due September 14203921 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 1.800% Global Notes due September 14, 2039 |
| Trading Symbol | T 39B |
| Security Exchange Name | NYSE |
| ATT Inc 700 Global Notes Due April 302040 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 7.00% Global Notes due April 30, 2040 |
| Trading Symbol | T 40 |
| Security Exchange Name | NYSE |
| Att Inc .4.25 Global Notes Due June 120437 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 4.25% Global Notes due June 1, 2043 |
| Trading Symbol | T 43 |
| Security Exchange Name | NYSE |
| Att Inc .4.875 Global Notes Due June 120448 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 4.875% Global Notes due June 1, 2044 |
| Trading Symbol | T 44 |
| Security Exchange Name | NYSE |
| Att Inc .4.250 Global Notes Due March 1205014 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 4.250% Global Notes due March 1, 2050 |
| Trading Symbol | T 50 |
| Security Exchange Name | NYSE |
| Att Inc .5.35 Global Notes Due November 1206623 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 5.35% Global Notes due November 1, 2066 |
| Trading Symbol | TBB |
| Security Exchange Name | NYSE |
| ATT Inc 5625 Global Notes Due August 12067 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 5.625% Global Notes due August 1, 2067 |
| Trading Symbol | TBC |
| Security Exchange Name | NYSE |
