Debt - Narrative (Details)	1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 31, 2021 USD ($)	Oct. 31, 2021 USD ($)	Oct. 31, 2020 USD ($)	Oct. 31, 2021 USD ($)	Oct. 31, 2020 USD ($)	Jul. 21, 2021 USD ($)	Jan. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Line of Credit Facility [Line Items]
Repayments of Slack Convertible Notes, net of capped call proceeds	$ 168,000,000	$ (1,348,000,000)	$ 0	$ (1,180,000,000)	$ 0
Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity								$ 3,000,000,000
Outstanding borrowings for line of credit		0		$ 0
Slack
Line of Credit Facility [Line Items]
Slack Convertible Notes						$ 1,339,000,000
Slack Convertible Notes
Line of Credit Facility [Line Items]
Repayments of convertible notes		1,300,000,000
Converted notes, amount		$ 852,000,000
Closing trading price
Line of Credit Facility [Line Items]
Long-term debt measurement input		100		100			100
Senior Notes | July 2021 Notes
Line of Credit Facility [Line Items]
Debt instrument, face amount	8,000,000,000
Proceeds from issuance of long-term debt	$ 7,900,000,000
Senior Notes | Significant Other Observable Inputs (Level 2)
Line of Credit Facility [Line Items]
Senior Notes fair value		$ 10,800,000,000		$ 10,800,000,000			$ 2,800,000,000
Convertible Debt | Slack Convertible Notes
Line of Credit Facility [Line Items]
Debt instrument, face amount		$ 863,000,000		$ 863,000,000		$ 863,000,000
Contractual interest rate		0.50%		0.50%		0.50%