Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions |
3 Months Ended | 12 Months Ended | ||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2019 |
Sep. 30, 2019 |
Jun. 30, 2019 |
Mar. 31, 2019 |
Dec. 31, 2018 |
Sep. 30, 2018 |
Jun. 30, 2018 |
Mar. 31, 2018 |
Sep. 30, 2017 |
Jun. 30, 2017 |
Mar. 31, 2017 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|||||||||||||||
| Earnings Per Share | ||||||||||||||||||||||||||||
| Net Income | $ 2,704 | [1],[2] | $ 3,949 | [1] | $ 3,974 | [1] | $ 4,348 | [1] | $ 5,130 | [1] | $ 4,816 | [1] | $ 5,248 | [1] | $ 4,759 | [1] | $ 4,816 | $ 5,248 | $ 4,759 | $ 14,975 | $ 19,953 | $ 29,847 | ||||||
| Less:Net income attributable to noncontrolling interest | (1,072) | (583) | (397) | |||||||||||||||||||||||||
| Net Income attributable to AT&T | $ 2,394 | [1],[2] | $ 3,700 | [1] | $ 3,713 | [1] | $ 4,096 | [1] | $ 4,858 | [1] | $ 4,718 | [1] | $ 5,132 | [1] | $ 4,662 | [1] | $ 4,718 | $ 5,132 | $ 4,662 | 13,903 | 19,370 | 29,450 | ||||||
| Less: Preferred stock dividends | (3) | 0 | 0 | |||||||||||||||||||||||||
| Net income attributable to common stock | 13,900 | 19,370 | 29,450 | |||||||||||||||||||||||||
| Share-based payment | 21 | 19 | 13 | |||||||||||||||||||||||||
| Numerator for diluted earnings per share | $ 13,921 | $ 19,389 | $ 29,463 | |||||||||||||||||||||||||
| Weighted-average number of common shares outstanding | 7,319 | 6,778 | 6,164 | |||||||||||||||||||||||||
| Share-based payment (in shares) | 29 | 28 | 19 | |||||||||||||||||||||||||
| Denominator for diluted earnings per share | 7,348 | 6,806 | 6,183 | |||||||||||||||||||||||||
| Basic earnings per share attributable to Common Stock | $ 0.33 | [3] | $ 0.50 | [3] | $ 0.51 | [3] | $ 0.56 | [3] | $ 0.66 | [3] | $ 0.65 | [3] | $ 0.81 | [3] | $ 0.75 | [3] | $ 0.65 | $ 0.81 | $ 0.75 | $ 1.90 | $ 2.85 | $ 4.77 | ||||||
| Diluted earnings per share attributable to Common Stock | $ 0.33 | [3] | $ 0.50 | [3] | $ 0.51 | [3] | $ 0.56 | [3] | $ 0.66 | [3] | $ 0.65 | [3] | $ 0.81 | [3] | $ 0.75 | [3] | $ 0.65 | $ 0.81 | $ 0.75 | $ 1.89 | $ 2.85 | $ 4.76 | ||||||
| ||||||||||||||||||||||||||||
| X | ||||||||||
- Definition Amount of increase (decrease) to net income used for calculating diluted earnings per share (EPS), resulting from the assumed exercise stock options, restrictive stock units (RSUs), convertible preferred stock of an employee stock ownership plan (ESOP), and other dilutive convertible securities. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- References No definition available.
|
| X | ||||||||||
- Definition The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period. Reference 1: http://www.xbrl.org/2003/role/exampleRef
|
| X | ||||||||||
- Definition Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition The portion of profit or loss for the period, net of income taxes, which is attributable to the parent. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount of Net Income (Loss) attributable to noncontrolling interest. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities, and addition from assumption of issuance of common shares for dilutive potential common shares; of income (loss) available to common shareholders. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition The amount of preferred stock dividends that is an adjustment to net income apportioned to common stockholders. No definition available.
|
| X | ||||||||||
- Definition The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|