Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss) before reclassifications	$ 1,342	$ (937)	$ 647
Amounts reclassified from accumulated OCI	(1,924)	136	(1,787)
Other comprehensive income (loss) attributable to AT&T	(763)	(801)	(1,140)
Accumulated Other Comprehensive Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income, beginning balance	3,529	4,330	5,470
Other comprehensive income (loss) attributable to AT&T	(763)	(801)	(1,140)
Accumulated other comprehensive income, ending balance	2,766	3,529	4,330
Foreign Currency Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income, beginning balance	(1,964)	(3,926)	(3,056)
Other comprehensive income (loss) before reclassifications	346	(125)	(870)
Amounts reclassified from accumulated OCI	0	2,087	0
Other comprehensive income (loss) attributable to AT&T	164	1,962	(870)
Accumulated other comprehensive income, ending balance	(1,800)	(1,964)	(3,926)
Net Unrealized Gains (Losses) on Available-for-Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income, beginning balance	45	111	48
Other comprehensive income (loss) before reclassifications	(143)	(63)	78
Amounts reclassified from accumulated OCI	8	(3)	(15)
Other comprehensive income (loss) attributable to AT&T	(135)	(66)	63
Accumulated other comprehensive income, ending balance	(90)	45	111
Net Unrealized Gains (Losses) on Derivative Instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income, beginning balance	(1,422)	(779)	(37)
Other comprehensive income (loss) before reclassifications	(648)	(715)	(811)
Amounts reclassified from accumulated OCI	96	72	69
Other comprehensive income (loss) attributable to AT&T	(576)	(643)	(742)
Accumulated other comprehensive income, ending balance	(1,998)	(1,422)	(779)
Defined Benefit Postretirement Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income, beginning balance	6,870	8,924	8,515
Other comprehensive income (loss) before reclassifications	1,787	(34)	2,250
Amounts reclassified from accumulated OCI	(2,028)	(2,020)	(1,841)
Other comprehensive income (loss) attributable to AT&T	(216)	(2,054)	409
Accumulated other comprehensive income, ending balance	6,654	$ 6,870	$ 8,924
Reclassification out of Accumulated Other Comprehensive Income [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amounts reclassified from accumulated OCI	(181)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Foreign Currency Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amounts reclassified from accumulated OCI	(182)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Net Unrealized Gains (Losses) on Available-for-Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amounts reclassified from accumulated OCI	0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Net Unrealized Gains (Losses) on Derivative Instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amounts reclassified from accumulated OCI	(24)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Defined Benefit Postretirement Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amounts reclassified from accumulated OCI	$ 25