Consolidated Statement Of Changes In Stockholders' Equity - 9 months ended Sep. 30, 2018 - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income Attributable to AT&T, net of tax [Member]	Noncontrolling Interest [Member]
Balance at beginning of year at Dec. 31, 2017	$ 142,007	$ 6,495	$ 89,563	$ 50,500	$ (12,714)	$ 7,017	$ 1,146
Balance at beginning of year (in shares) at Dec. 31, 2017		6,495			(356)
Issuance of stock		$ 1,126	35,473
Issuance of stock (in shares)		1,126
Repurchase and acquisition of common stock					$ (641)
Repurchase and acquisition of common stock (in shares)					(19)
Issuance of treasury stock			(49)		$ 869
Issuance of treasury stock, (in shares)					24
Share-based payments			719
Net income attributable to AT&T ($2.19 per diluted share)	14,512			14,512
Dividends to stockholders ($1.50 per share)				(10,388)
Other comprehensive income attributable to AT&T	(976)					(976)
Net income attributable to noncontrolling interest	311						311
Contributions							8
Distributions							(332)
Acquisitions of noncontrolling interest							1
Change related to acquisition of interests held by noncontrolling owners							(9)
Translation adjustments attributable to noncontrolling interest, net of taxes	(37)						(37)
Balance at end of period at Sep. 30, 2018	184,971	$ 7,621	$ 125,706	57,624	$ (12,486)	5,383	1,123
Balance at end of period (in shares) at Sep. 30, 2018		7,621			(351)
Amounts reclassifed to retained earnings/Cumulative effect of accounting changes	$ (658)			$ 3,000		$ (658)	$ 35