Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 3,949	$ 4,816	$ 12,271	$ 14,823
Foreign currency:
Translation adjustment (includes $(17), $(7), $(15) and $(37) attributable to noncontrolling interest), net of taxes of $(69), $(2), $(21) and $(145)	(342)	(14)	(181)	(824)
Securities:
Net unrealized gains (losses), net of taxes of $7, $(4) $22 and $(8)	25	(10)	67	(22)
Derivative instruments:
Net unrealized gains (losses), net of taxes of $(168), $0, $(299) and $68	(516)	4	(1,006)	257
Reclassification adjustment included in net income, net of taxes of $2, $3, $7 and $9	7	12	24	35
Defined benefit postretirement plans:
Net prior service (cost) credit arising during period, net of taxes of $0, $0, $0 and $173	0	0	0	530
Amortization of net prior service credit included in net income, net of taxes of $(112), $(108), $(332) and $(322)	(343)	(332)	(1,031)	(989)
Other comprehensive income (loss)	(1,169)	(340)	(2,127)	(1,013)
Total comprehensive income	2,780	4,476	10,144	13,810
Less: Total comprehensive income attributable to noncontrolling interest	(232)	(91)	(747)	(274)
Total Comprehensive Income Attributable to AT&T	$ 2,548	$ 4,385	$ 9,397	$ 13,536