Segment Information (Reconciliation Of Operating Income Loss to Consolidated Statement Of Income) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Reconciling Item For Operating Income (Loss) From Segment To Consolidated Statements Of Income [Line Items]
AT&T Operating Income	$ 7,901	$ 7,269	$ 22,634	$ 19,936
Interest expense	2,083	2,051	6,373	5,845
Equity in net income (loss) of affiliates	3	(64)	36	(71)
Other income (expense) - net	(935)	1,053	(967)	5,108
Income Before Income Taxes	4,886	6,207	15,330	19,128
Operating Segments [Member]
Segment Reporting Reconciling Item For Operating Income (Loss) From Segment To Consolidated Statements Of Income [Line Items]
AT&T Operating Income	10,713	10,841	31,792	28,014
Equity in net income (loss) of affiliates	28	(31)	162	(34)
Income Before Income Taxes	10,741	10,810	31,954	27,980
Operating Segments [Member] \| Communications [Member]
Segment Reporting Reconciling Item For Operating Income (Loss) From Segment To Consolidated Statements Of Income [Line Items]
AT&T Operating Income	8,036	8,151	24,718	24,501
Equity in net income (loss) of affiliates	0	(1)	0	(3)
Income Before Income Taxes	8,036	8,150	24,718	24,498
Operating Segments [Member] \| WarnerMedia [Member]
Segment Reporting Reconciling Item For Operating Income (Loss) From Segment To Consolidated Statements Of Income [Line Items]
AT&T Operating Income	2,529	2,567	6,742	3,047
Equity in net income (loss) of affiliates	15	(39)	137	(55)
Income Before Income Taxes	2,544	2,528	6,879	2,992
Operating Segments [Member] \| Latin America [Member]
Segment Reporting Reconciling Item For Operating Income (Loss) From Segment To Consolidated Statements Of Income [Line Items]
AT&T Operating Income	(179)	(210)	(573)	(486)
Equity in net income (loss) of affiliates	13	9	25	24
Income Before Income Taxes	(166)	(201)	(548)	(462)
Operating Segments [Member] \| Xandr [Member]
Segment Reporting Reconciling Item For Operating Income (Loss) From Segment To Consolidated Statements Of Income [Line Items]
AT&T Operating Income	327	333	905	952
Equity in net income (loss) of affiliates	0	0	0	0
Income Before Income Taxes	327	333	905	952
Certain Significant Items [Member]
Segment Reporting Reconciling Item For Operating Income (Loss) From Segment To Consolidated Statements Of Income [Line Items]
AT&T Operating Income	(39)	(75)	(381)	(407)
Certain Significant Items [Member] \| Merger and intergration items [Member]
Segment Reporting Reconciling Item For Operating Income (Loss) From Segment To Consolidated Statements Of Income [Line Items]
AT&T Operating Income	(190)	(362)	(651)	(794)
Certain Significant Items [Member] \| Amortization of intangibles acquired [Member]
Segment Reporting Reconciling Item For Operating Income (Loss) From Segment To Consolidated Statements Of Income [Line Items]
AT&T Operating Income	(1,771)	(2,329)	(5,719)	(4,669)
Certain Significant Items [Member] \| Employee separate charges [Member]
Segment Reporting Reconciling Item For Operating Income (Loss) From Segment To Consolidated Statements Of Income [Line Items]
AT&T Operating Income	(39)	(75)	(381)	(259)
Certain Significant Items [Member] \| Natural Disaster Charges [Member]
Segment Reporting Reconciling Item For Operating Income (Loss) From Segment To Consolidated Statements Of Income [Line Items]
AT&T Operating Income	0	0	0	(104)
Certain Significant Items [Member] \| Segment equity in net (income) loss of affiliates
Segment Reporting Reconciling Item For Operating Income (Loss) From Segment To Consolidated Statements Of Income [Line Items]
AT&T Operating Income	(28)	31	(162)	34
Consolidations [Member]
Segment Reporting Reconciling Item For Operating Income (Loss) From Segment To Consolidated Statements Of Income [Line Items]
AT&T Operating Income	(427)	(439)	(1,344)	(1,230)
Eliminations and consolidations [Member]
Segment Reporting Reconciling Item For Operating Income (Loss) From Segment To Consolidated Statements Of Income [Line Items]
AT&T Operating Income	$ (385)	$ (367)	$ (1,063)	$ (1,022)

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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