Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2021	Apr. 30, 2020
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	$ 87,531	$ 81,552
Other comprehensive loss before reclassifications, net	(259)	(3,398)
Reclassifications related to business dispositions	4,059
Reclassifications to income, net	20	35
Ending balance	84,592	74,110
Accumulated other comprehensive loss
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(11,766)	(12,805)
Ending balance	(7,946)	(16,168)
Currency  Translation and Other
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(10,772)	(11,827)
Other comprehensive loss before reclassifications, net	(225)	(3,256)
Reclassifications related to business dispositions	3,258
Reclassifications to income, net	0	0
Ending balance	(7,739)	(15,083)
Net Investment Hedges
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	1,296	1,517
Other comprehensive loss before reclassifications, net	(7)	157
Reclassifications related to business dispositions	(1,195)
Reclassifications to income, net	0	0
Ending balance	94	1,674
Cash Flow Hedges
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(304)	(539)
Other comprehensive loss before reclassifications, net	(26)	(295)
Reclassifications related to business dispositions	30
Reclassifications to income, net	16	16
Ending balance	(284)	(818)
Minimum Pension  Liability
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(1,986)	(1,956)
Other comprehensive loss before reclassifications, net	(1)	(4)
Reclassifications related to business dispositions	1,966
Reclassifications to income, net	4	19
Ending balance	$ (17)	$ (1,941)