Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 4,816	$ 3,123	$ 14,823	$ 10,711
Foreign currency:
Translation adjustment (includes $(7), $10, $(37) and $6 attributable to noncontrolling interest), net of taxes of $(2), $74, $(145) and $580	(14)	151	(824)	490
Available-for-sale securities:
Net unrealized gains (losses), net of taxes of $(4), $28, $(8) and $72	(10)	45	(22)	128
Reclassification adjustment included in net income, net of taxes of $0, $(50), $0 and $(54)	0	(79)	0	(86)
Cash flow hedges:
Net unrealized gains (losses), net of taxes of $0, $178, $68 and $(94)	4	330	257	(174)
Reclassification adjustment included in net income, net of taxes of $3, $5, $9 and $15	12	10	35	29
Defined benefit postretirement plans:
Net prior service (cost) credit arising during period, net of taxes of $0, $0, $173 and $594	0	0	530	969
Amortization of net prior service credit included in net income, net of taxes of $(108), $(157), $(322) and $(447)	(332)	(256)	(989)	(731)
Other comprehensive income (loss)	(340)	201	(1,013)	625
Total comprehensive income	4,476	3,324	13,810	11,336
Less: Total comprehensive income attributable to noncontrolling interest	(91)	(104)	(274)	(304)
Total Comprehensive Income Attributable to AT&T	$ 4,385	$ 3,220	$ 13,536	$ 11,032