Income Taxes (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Income Tax Disclosure [Abstract]
Benefit from (provision for) income taxes	[1]	$ 1,786	$ (73)	$ 1,838	$ (163)
Pretax income		839	$ 164	$ 886	$ 646
Effective tax rate				(207.00%)	25.00%
Discrete tax benefit		2,000
Reasonably possible decrease of unrecognized tax benefits		$ 6		$ 6

[1] During the three months ended July 31, 2020 the Company recorded approximately $2.0 billion of benefit from income taxes due to a one-time discrete tax item from the recognition of deferred tax assets related to an intra-entity transfer of intangible property.