Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Jul. 31, 2021	Apr. 30, 2021	Jul. 31, 2020	Apr. 30, 2020
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	$ 84,592	$ 87,531	$ 74,110	$ 81,552
Other comprehensive loss before reclassifications, net	(73)	(259)	356	(3,398)
Reclassifications related to business dispositions		4,059
Reclassifications to income, net	43	20	28	35
Ending balance	87,127	84,592	81,197	74,110
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(7,946)	(11,766)	(16,168)	(12,805)
Ending balance	(7,976)	(7,946)	(15,784)	(16,168)
Currency  Translation and Other
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(7,739)	(10,772)	(15,083)	(11,827)
Other comprehensive loss before reclassifications, net	123	(225)	246	(3,256)
Reclassifications related to business dispositions		3,258
Reclassifications to income, net	0	0	0	0
Ending balance	(7,616)	(7,739)	(14,837)	(15,083)
Net Investment Hedges
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	94	1,296	1,674	1,517
Other comprehensive loss before reclassifications, net	0	(7)	(191)	157
Reclassifications related to business dispositions		(1,195)
Reclassifications to income, net	0	0	0	0
Ending balance	94	94	1,483	1,674
Cash Flow Hedges
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(284)	(304)	(818)	(539)
Other comprehensive loss before reclassifications, net	(193)	(26)	303	(295)
Reclassifications related to business dispositions		30
Reclassifications to income, net	38	16	10	16
Ending balance	(439)	(284)	(505)	(818)
Minimum Pension  Liability
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(17)	(1,986)	(1,941)	(1,956)
Other comprehensive loss before reclassifications, net	(3)	(1)	(2)	(4)
Reclassifications related to business dispositions		1,966
Reclassifications to income, net	5	4	18	19
Ending balance	$ (15)	$ (17)	$ (1,925)	$ (1,941)