Segment Information - Reconciliation of Total Reportable Segments Operating Income to Consolidated Income before Provision for Income Taxes (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Operating Income	$ 32,448	$ 28,798	$ 30,378
Severance charges	(209)	(221)	(204)
Other components of net periodic pension and benefit charges (Note 11)	(769)	(817)	(813)
Loss on spectrum licenses (Note 3)	(223)	(1,195)	0
Impairment charges	0	0	(186)
Net gain from dispositions of assets and businesses	706	(126)	261
Equity in earnings (losses) of unconsolidated businesses	145	(45)	(15)
Other income (expense), net	312	(539)	(2,900)
Interest expense	(3,485)	(4,247)	(4,730)
Income Before Provision For Income Taxes	29,420	23,967	22,733
Operating Segments
Segment Reporting Information [Line Items]
Operating Income	33,392	32,629	32,723
Corporate and other
Segment Reporting Information [Line Items]
Operating Income	$ (449)	$ (1,472)	$ (1,403)