Intangible Assets Acquired Through Business Combinations and Goodwill - Intangible Assets Acquired From Business Combinations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019	Jan. 31, 2020
Finite-lived Intangible Assets [Roll Forward]
Intangible assets, gross, beginning balance			$ 6,922
Additions and retirements, net			512
Intangible assets, gross, ending balance	$ 7,434		7,434
Accumulated amortization, beginning balance			(2,198)
Expense and retirements, net			(838)
Accumulated amortization, ending balance	(3,036)		(3,036)
Intangible assets, net, beginning balance			4,724
Intangible assets, net, ending balance	4,398		$ 4,398
Weighted Average Remaining Useful Life (Years)			5 years 3 months 18 days
Amortization of intangible assets	283	$ 266	$ 838	$ 522
Customer contract assets	574		574		$ 449
Other assets
Finite-lived Intangible Assets [Roll Forward]
Customer contract assets	54		54		$ 93
Acquired developed technology
Finite-lived Intangible Assets [Roll Forward]
Intangible assets, gross, beginning balance			3,598
Additions and retirements, net			190
Intangible assets, gross, ending balance	3,788		3,788
Accumulated amortization, beginning balance			(1,249)
Expense and retirements, net			(494)
Accumulated amortization, ending balance	(1,743)		(1,743)
Intangible assets, net, beginning balance			2,349
Intangible assets, net, ending balance	2,045		$ 2,045
Weighted Average Remaining Useful Life (Years)			3 years 4 months 24 days
Customer relationships
Finite-lived Intangible Assets [Roll Forward]
Intangible assets, gross, beginning balance			$ 3,252
Additions and retirements, net			316
Intangible assets, gross, ending balance	3,568		3,568
Accumulated amortization, beginning balance			(888)
Expense and retirements, net			(331)
Accumulated amortization, ending balance	(1,219)		(1,219)
Intangible assets, net, beginning balance			2,364
Intangible assets, net, ending balance	2,349		$ 2,349
Weighted Average Remaining Useful Life (Years)			7 years
Other
Finite-lived Intangible Assets [Roll Forward]
Intangible assets, gross, beginning balance			$ 72
Additions and retirements, net			6
Intangible assets, gross, ending balance	78		78
Accumulated amortization, beginning balance			(61)
Expense and retirements, net			(13)
Accumulated amortization, ending balance	(74)		(74)
Intangible assets, net, beginning balance			11
Intangible assets, net, ending balance	$ 4		$ 4
Weighted Average Remaining Useful Life (Years)			3 years 7 months 6 days