Segment Information (Reconciliation Of Operating Income Loss to Consolidated Statement Of Income) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment Contribution	$ 3,934	$ 4,886	$ 12,697	$ 15,330
AT&T Operating Income	6,132	7,901	17,150	22,634
Equity in net income (loss) of affiliates	5	3	(11)	36
Interest Expense	1,972	2,083	6,031	6,373
Other income (expense) - net	(231)	(935)	1,589	(967)
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment Contribution	9,241	10,741	29,101	31,954
AT&T Operating Income	9,216	10,713	29,045	31,792
Equity in net income (loss) of affiliates	25	28	56	162
Operating Segments \| Communications
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment Contribution	7,648	8,036	23,963	24,718
AT&T Operating Income	7,648	8,036	23,963	24,718
Equity in net income (loss) of affiliates	0	0	0	0
Operating Segments \| WarnerMedia
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment Contribution	1,770	2,871	5,700	7,784
AT&T Operating Income	1,759	2,856	5,670	7,647
Equity in net income (loss) of affiliates	11	15	30	137
Operating Segments \| Latin America
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment Contribution	(177)	(166)	(562)	(548)
AT&T Operating Income	(191)	(179)	(588)	(573)
Equity in net income (loss) of affiliates	14	13	26	25
Corporate and Other
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
AT&T Operating Income	(642)	(427)	(1,804)	(1,344)
Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Merger and integration items	(38)	(190)	(431)	(651)
Amortization of intangibles acquired	(1,921)	(1,771)	(6,122)	(5,719)
Asset impairments and abandonments	(73)	0	(2,515)	0
Gain on spectrum transaction	0	0	900	0
Employee separation costs and benefit-related losses	(40)	(39)	(924)	(381)
Equity in net income (loss) of affiliates	(25)	(28)	(56)	(162)
Eliminations and consolidations
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
AT&T Operating Income	$ (370)	$ (385)	$ (999)	$ (1,063)

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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