Consolidated Statement Of Changes In Stockholders' Equity - 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			$ 0
Issuance of stock (in shares)			0
Repurchase and acquisition of common stock						$ (164)
Repurchase and acquisition of common stock (in shares)						(4)
Issuance of treasury stock				(4)		$ 446
Issuance of treasury stock, (in shares)						12
Share-based payments				(155)
Net income attributable to AT&T ($0.56 and $0.75 per diluted share)		4,662			4,662
Dividends to stockholders ($0.51 and $0.50 per share)					(3,092)
Other comprehensive income attributable to AT&T							1,024
Net income attributable to noncontrolling interest		97						97
Interest acquired by noncontrolling owners								0
Distributions								(124)
Translation adjustments attributable to noncontrolling interest, net of taxes		2						2
Balance at end of period at Mar. 31, 2018		147,076	$ 6,495	89,404	55,067	$ (12,432)	7,386	1,156
Balance at end of period (in shares) at Mar. 31, 2018			6,495			(348)
Amounts reclassified to retained earnings	[1]						(655)
Cumulative effect of accounting changes, net of taxes					2,997			35
Balance at beginning of year at Dec. 31, 2018		193,884	$ 7,621	125,525	58,753	$ (12,059)	4,249	9,795
Balance at beginning of year (in shares) at Dec. 31, 2018			7,621			(339)
Issuance of stock			$ 0
Issuance of stock (in shares)			0
Repurchase and acquisition of common stock						$ (208)
Repurchase and acquisition of common stock (in shares)						(7)
Issuance of treasury stock				(77)		$ 815
Issuance of treasury stock, (in shares)						22
Share-based payments				(274)
Net income attributable to AT&T ($0.56 and $0.75 per diluted share)		4,096			4,096
Dividends to stockholders ($0.51 and $0.50 per share)					(3,741)
Other comprehensive income attributable to AT&T							96
Net income attributable to noncontrolling interest		252						252
Interest acquired by noncontrolling owners								9
Distributions								(246)
Translation adjustments attributable to noncontrolling interest, net of taxes		0						0
Balance at end of period at Mar. 31, 2019		$ 194,951	$ 7,621	$ 125,174	59,424	$ (11,452)	$ 4,345	9,839
Balance at end of period (in shares) at Mar. 31, 2019			7,621			(324)
Cumulative effect of accounting changes, net of taxes					$ 316			$ 29

[1] With the adoption of ASU 2016-01, the unrealized (gains) losses on our equity investments are reclassifed to retained earnings.