Equity and Accumulated Other Comprehensive Income - Changes in AOCI (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
AOCI Including Portion Attributable to Noncontrolling Interest [Abstract]
Beginning Balance	$ 62,835
Other comprehensive loss	(2,935)
Amounts reclassified to net income	435
Net other comprehensive loss	(2,500)
Ending Balance	61,653	$ 57,460
Foreign currency translation adjustments
AOCI Including Portion Attributable to Noncontrolling Interest [Abstract]
Beginning Balance	(584)
Other comprehensive loss	(120)
Amounts reclassified to net income	0
Net other comprehensive loss	(120)
Ending Balance	(704)
Unrealized gain (loss) on cash flow hedges
AOCI Including Portion Attributable to Noncontrolling Interest [Abstract]
Beginning Balance	(816)
Other comprehensive loss	(2,814)
Amounts reclassified to net income	604
Net other comprehensive loss	(2,210)
Ending Balance	(3,026)
Unrealized gain (loss) on marketable securities
AOCI Including Portion Attributable to Noncontrolling Interest [Abstract]
Beginning Balance	27
Other comprehensive loss	(1)
Amounts reclassified to net income	0
Net other comprehensive loss	(1)
Ending Balance	26
Defined benefit pension and postretirement plans
AOCI Including Portion Attributable to Noncontrolling Interest [Abstract]
Beginning Balance	2,371
Other comprehensive loss	0
Amounts reclassified to net income	(169)
Net other comprehensive loss	(169)
Ending Balance	2,202
Accumulated Other Comprehensive Income
AOCI Including Portion Attributable to Noncontrolling Interest [Abstract]
Beginning Balance	998	2,370
Net other comprehensive loss	(2,500)	(154)
Ending Balance	$ (1,502)	$ 2,216

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Amount after tax, before reclassification adjustments of other comprehensive income (loss).

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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