Equity and Accumulated Other Comprehensive Income (Loss) - Changes in AOCI (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
AOCI Including Portion Attributable to Noncontrolling Interest [Abstract]
Beginning Balance			$ 69,272
Other comprehensive loss			(1,208)
Amounts reclassified to net income			570
Net other comprehensive loss			(638)
Ending Balance	$ 78,489	$ 66,530	78,489	$ 66,530
Accumulated Other Comprehensive Loss
AOCI Including Portion Attributable to Noncontrolling Interest [Abstract]
Beginning Balance	(234)	(1,274)	(71)	998
Net other comprehensive loss	(475)	462	(638)	(1,810)
Ending Balance	(709)	$ (812)	(709)	$ (812)
Foreign  currency translation adjustments
AOCI Including Portion Attributable to Noncontrolling Interest [Abstract]
Beginning Balance			(404)
Other comprehensive loss			(126)
Amounts reclassified to net income			0
Net other comprehensive loss			(126)
Ending Balance	(530)		(530)
Unrealized loss on cash flow hedges
AOCI Including Portion Attributable to Noncontrolling Interest [Abstract]
Beginning Balance			(1,387)
Other comprehensive loss			(1,077)
Amounts reclassified to net income			1,035
Net other comprehensive loss			(42)
Ending Balance	(1,429)		(1,429)
Unrealized gain (loss) on marketable securities
AOCI Including Portion Attributable to Noncontrolling Interest [Abstract]
Beginning Balance			25
Other comprehensive loss			(5)
Amounts reclassified to net income			0
Net other comprehensive loss			(5)
Ending Balance	20		20
Defined benefit pension and postretirement plans
AOCI Including Portion Attributable to Noncontrolling Interest [Abstract]
Beginning Balance			1,695
Other comprehensive loss			0
Amounts reclassified to net income			(465)
Net other comprehensive loss			(465)
Ending Balance	$ 1,230		$ 1,230