Consolidated Statement Of Changes In Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Preferred Stock Preferred Stock - Series A	Preferred Stock Preferred Stock - Series B	Preferred Stock Preferred Stock - Series C	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income Attributable to AT&T, net of tax	Noncontrolling Interest
Balance at beginning of period at Dec. 31, 2020	$ 179,240	$ 0	$ 0	$ 0	$ 7,621	$ 130,175	$ 37,457	$ (17,910)	$ 4,330	$ 17,567
Balance at beginning of period (in shares) at Dec. 31, 2020		0	0	0	7,621			(495)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Distribution of WarnerMedia						0	0
Repurchase and acquisition of common stock								$ (225)
Repurchase and acquisition of common stock (in shares)								(8)
Issuance/reissuance of treasury stock						(77)		$ (816)
Issuance/reissuance of treasury stock (in shares)								22
Share-based payments						(63)
Net income attributable to AT&T	15,038						15,038
Preferred stock dividends							(188)
Common stock dividends ($0.2775, $0.52, $0.8325 and $1.56 per share)							(11,216)
Other comprehensive income attributable to AT&T	(1,987)								(1,987)
Net income attributable to noncontrolling interest	1,051									1,051
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests										0
Distributions										(1,084)
Translation adjustments attributable to noncontrolling interest, net of taxes	2									(2)
Balance at end of period at Sep. 30, 2021	181,303	$ 0	$ 0	$ 0	$ 7,621	130,035	41,091	$ (17,319)	2,343	17,532
Balance at end of period (in shares) at Sep. 30, 2021		0	0	0	7,621			(481)
Balance at beginning of period at Jun. 30, 2021	179,846	$ 0	$ 0	$ 0	$ 7,621	129,941	38,947	$ (17,332)	3,119	17,550
Balance at beginning of period (in shares) at Jun. 30, 2021		0	0	0	7,621			(481)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Distribution of WarnerMedia						0	0
Repurchase and acquisition of common stock								$ (10)
Repurchase and acquisition of common stock (in shares)								(1)
Issuance/reissuance of treasury stock						(2)		$ (23)
Issuance/reissuance of treasury stock (in shares)								1
Share-based payments						(96)
Net income attributable to AT&T	5,918						5,918
Preferred stock dividends							(36)
Common stock dividends ($0.2775, $0.52, $0.8325 and $1.56 per share)							(3,738)
Other comprehensive income attributable to AT&T									(776)
Net income attributable to noncontrolling interest	355									355
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests										0
Distributions										(369)
Translation adjustments attributable to noncontrolling interest, net of taxes	4									(4)
Balance at end of period at Sep. 30, 2021	181,303	$ 0	$ 0	$ 0	$ 7,621	130,035	41,091	$ (17,319)	2,343	17,532
Balance at end of period (in shares) at Sep. 30, 2021		0	0	0	7,621			(481)
Balance at beginning of period at Dec. 31, 2021	183,855	$ 0	$ 0	$ 0	$ 7,621	130,112	42,350	$ (17,280)	3,529	17,523
Balance at beginning of period (in shares) at Dec. 31, 2021		0	0	0	7,621			(480)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Distribution of WarnerMedia						(6,832)	(45,041)
Repurchase and acquisition of common stock								$ (875)
Repurchase and acquisition of common stock (in shares)								(43)
Issuance/reissuance of treasury stock						(149)		$ (1,007)
Issuance/reissuance of treasury stock (in shares)								28
Share-based payments						(198)
Net income attributable to AT&T	14,993						14,993
Preferred stock dividends							(171)
Common stock dividends ($0.2775, $0.52, $0.8325 and $1.56 per share)							(6,004)
Other comprehensive income attributable to AT&T	(656)								(656)
Net income attributable to noncontrolling interest	1,107									1,107
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests										(34)
Distributions										(1,024)
Translation adjustments attributable to noncontrolling interest, net of taxes	0									0
Balance at end of period at Sep. 30, 2022	139,978	$ 0	$ 0	$ 0	$ 7,621	122,933	6,127	$ (17,148)	2,873	17,572
Balance at end of period (in shares) at Sep. 30, 2022		0	0	0	7,621			(495)
Balance at beginning of period at Jun. 30, 2022	135,307	$ 0	$ 0	$ 0	$ 7,621	122,850	2,128	$ (17,160)	2,307	17,561
Balance at beginning of period (in shares) at Jun. 30, 2022		0	0	0	7,621			(495)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Distribution of WarnerMedia						0	0
Repurchase and acquisition of common stock								$ (3)
Repurchase and acquisition of common stock (in shares)								0
Issuance/reissuance of treasury stock						(5)		$ (15)
Issuance/reissuance of treasury stock (in shares)								0
Share-based payments						(88)
Net income attributable to AT&T	6,026						6,026
Preferred stock dividends							(36)
Common stock dividends ($0.2775, $0.52, $0.8325 and $1.56 per share)							(1,991)
Other comprehensive income attributable to AT&T									566
Net income attributable to noncontrolling interest	373									373
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests										(18)
Distributions										(344)
Translation adjustments attributable to noncontrolling interest, net of taxes	0									0
Balance at end of period at Sep. 30, 2022	$ 139,978	$ 0	$ 0	$ 0	$ 7,621	$ 122,933	$ 6,127	$ (17,148)	$ 2,873	$ 17,572
Balance at end of period (in shares) at Sep. 30, 2022		0	0	0	7,621			(495)