Segment Information - Reconciliation of Segments Operating Income to Consolidated Income (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Operating income	$ 6,579	$ 7,709
Other components of net periodic benefit charges	(203)	(203)
Loss on spectrum license transaction	(1,195)	0
Equity in losses of unconsolidated businesses	(12)	(6)
Other income, net	143	295
Interest expense	(1,034)	(1,210)
Income Before Provision For Income Taxes	5,676	6,788
Operating Segments
Segment Reporting Information [Line Items]
Operating income	8,236	8,298
Corporate and other
Segment Reporting Information [Line Items]
Operating income	$ (259)	$ (386)