Leases and Other Commitments - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2021	Oct. 31, 2020	Oct. 31, 2021	Oct. 31, 2020	Jul. 21, 2021
Other Commitments [Line Items]
Operating lease termination option			1 year
Operating lease cost	$ 294	$ 278	$ 818	$ 815
Operating cash outflows for operating leases	210	222	664	672
Operating leases	37	$ 196	174	$ 562
Sublease income, next five years	189		189
Sublease income, thereafter	29		29
Operating leases, not yet commenced	1,400		1,400
Letter of credit
Other Commitments [Line Items]
Value of outstanding letters of credit	$ 131		$ 131
Slack
Other Commitments [Line Items]
Operating lease right-of-use assets					$ 208
Operating lease liabilities					$ (283)
Minimum
Other Commitments [Line Items]
Operating lease term	1 year		1 year
Operating lease term, not yet commenced	3 years		3 years
Maximum
Other Commitments [Line Items]
Operating lease term	18 years		18 years
Operating lease term, not yet commenced	18 years		18 years