Investments - Gains (Losses) on Strategic Investments, Net (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Investment Holdings [Line Items]
Net unrealized gains (loss) recognized		$ 1,000		$ 1,600
Gains on strategic investments, net	[1]	1,036	$ 6	1,910	$ 396
Publicly traded securities
Investment Holdings [Line Items]
Net unrealized gains (loss) recognized		997	(84)	1,620	132
Privately held securities
Investment Holdings [Line Items]
Net unrealized gains (loss) recognized		25	77	1	199
Equity securities
Investment Holdings [Line Items]
Net realized gains (losses) recognized		11	14	299	76
Debt securities
Investment Holdings [Line Items]
Net realized gains (losses) recognized		$ 3	$ (1)	$ (10)	$ (11)

[1] In September 2020, one of the Company’s strategic investments completed its initial public offering, resulting in an unrealized gain of $1.1 billion during the three and nine months ended October 31, 2020.