Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator for basic earnings per share:
Net Income	$ 3,168	$ 3,949	$ 9,694	$ 12,271
Less: Net income attributable to noncontrolling interest	(352)	(249)	(987)	(762)
Net Income Attributable to AT&T	2,816	3,700	8,707	11,509
Less: Preferred stock dividends	(54)	0	(138)	0
Net Income Attributable to Common Stock	2,762	3,700	8,569	11,509
Dilutive potential common shares:
Share-based payment	5	6	16	16
Numerator for diluted earnings per share	$ 2,767	$ 3,706	$ 8,585	$ 11,525
Denominator for basic earnings per share:
Weighted average number of common shares outstanding (in shares)	7,147	7,327	7,160	7,321
Dilutive potential common shares:
Share-based payment (in shares)	26	29	26	29
Denominator for diluted earnings per share (in shares)	7,173	7,356	7,186	7,350
Basic earnings per share attributable to Common Stock (in dollars per share)	$ 0.39	$ 0.50	$ 1.19	$ 1.57
Diluted earnings per share attributable to Common Stock (in dollars per share)	$ 0.39	$ 0.50	$ 1.19	$ 1.57