| Document and Entity Information | Dec. 06, 2019 |
| Document And Entity Information [Line Items] | |
| Amendment Flag | false |
| Entity Central Index Key | 0000732717 |
| Document Type | 8-K |
| Document Period End Date | Dec. 6, 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 |
| 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 1875 Global Notes Due December 42020 [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 265 Global Notes Due December 172021 [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 145 Global Notes Due June 12022 [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 250 Global Notes Due March 152023 [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 520232 [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 195 Global Notes Due September 152023 [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 240 Global Notes Due March 152024 [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 350 Global Notes Due December 172025 [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 0250 Global Notes Due March 42026 [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 180 Global Notes Due September 52026 [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 290 Percent Global Notes Due December 42026 [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 235 Global Notes Due September 52029 [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 4375 Global Notes Due September 142029 [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 260 Global Notes Due December 172029 [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 0800 Global Notes Due March 42030 [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 355 Global Notes Due December 172032 [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 520 Global Notes Due November 182033 [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 3375 Global Notes Due March 152034 [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 245 Global Notes Due March 152035 [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 315 Global Notes Due September 42036 [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 1800 Global Notes Due September 142039 [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 425 Global Notes Due June 12043 [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 4875 Global Notes Due June 12044 [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 535 Global Notes Due November 12066 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | AT&T Inc. 5.35% Global Notes due November 1, 2066 |
| Trading Symbol | T BB |
| 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 | T BC |
| Security Exchange Name | NYSE |
