Equity - Narrative (Details) $ / shares in Units, $ in Thousands				1 Months Ended				2 Months Ended	12 Months Ended			13 Months Ended
	Mar. 03, 2021 shares	Mar. 01, 2021 vote $ / shares shares	Feb. 28, 2021 vote	Sep. 30, 2020 USD ($) class $ / shares shares	Mar. 31, 2020 shares	Mar. 31, 2019 USD ($) shares	Dec. 31, 2017 $ / shares shares	Jun. 30, 2020 USD ($)	Jan. 31, 2022 USD ($) $ / shares shares	Jan. 31, 2021 USD ($) $ / shares shares	Jan. 31, 2020 USD ($) $ / shares shares	Apr. 30, 2020 USD ($)	Feb. 29, 2020 $ / shares	Jan. 31, 2019 shares
Share-based Compensation Arrangement by Share-based Payment Award
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)										(182,271,099)
Preferred stock, shares authorized (in shares)				200,000,000					200,000,000	200,000,000
Preferred stock, par value (in dollars per share) | $ / shares				$ 0.0001					$ 0.0001	$ 0.0001
Common stock, number of classes of stock | class				2
Conversion, percent threshold			10.00%
Common stock reserved for future issuances (shares)									105,310,457	112,494,580
Options granted (shares)									0	876,961	46,934,532
Granted (per share) | $ / shares										$ 22.67	$ 4.41
Intrinsic value of shares exercised | $									$ 5,700,000	$ 2,000,000	$ 89,900
Grant date fair value of vested shares | $									81,000	90,900	53,500
Proceeds from repayments of a nonrecourse promissory note | $									0	2,090	0
Stock-based compensation, net of amounts capitalized | $									$ 605,095	$ 301,441	78,399
Shares subject to repurchase (in shares)									45,834	245,633
Compensation modification cost | $										$ 2,700	$ 14,000	$ 16,700
Unrecognized share-based compensation expense | $									$ 1,400,000
Unrecognized share-based compensation expense recognition period (term)									3 years
Employee stock purchase rights under the 2020 ESPP
Share-based Compensation Arrangement by Share-based Payment Award
Common stock reserved for future issuances (shares)									8,208,724	5,700,000
Stock market discount									85.00%
Offering period									6 months
Stock options
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period (years)									4 years
Expiration period (years)									10 years
RSUs
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period (years)					4 years
Share-based compensation arrangement by share-based payment award, equity instruments other than options, nonvested, number									9,612,323	9,348,557	0
Vested (shares)									3,186,218	36,436
Stock-based compensation, net of amounts capitalized | $				$ 55,500
2020 Plan | RSUs
Share-based Compensation Arrangement by Share-based Payment Award
Common stock reserved for future issuances (shares)									5,081,999	1,828,083
2012 Plan | Stock options
Share-based Compensation Arrangement by Share-based Payment Award
Common stock reserved for future issuances (shares)									42,043,097	64,574,656
Expiration period (years)									10 years
2012 Plan | RSA
Share-based Compensation Arrangement by Share-based Payment Award
Grant date fair value of shares other than options vested | $										$ 100	$ 6,700
2012 Plan | RSUs
Share-based Compensation Arrangement by Share-based Payment Award
Common stock reserved for future issuances (shares)									4,530,324	7,520,474
Out of the Plans | RSA
Share-based Compensation Arrangement by Share-based Payment Award
Share-based compensation arrangement by share-based payment award, equity instruments other than options, nonvested, number									380,260	741,911	1,603,562			1,652,446
Vested (shares)									361,651	861,651	442,222
Out of the Plans | RSA | Privately-Held Company
Share-based Compensation Arrangement by Share-based Payment Award
Share-based compensation arrangement by share-based payment award, equity instruments other than options, nonvested, number									130,260
Issuance of common stock in connection with a business combination (in shares)						661,635
Vested (shares)						215,031
Stock-based compensation, net of amounts capitalized | $						$ 1,100
Service period						4 years
Out of the Plans | RSA | Privately-Held Company | Grant Date
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period (years)						4 years
Out of the Plans | RSA | Promissory Notes
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period (years)							5 years
Shares authorized (shares)							1,250,000
Shares issued (per share) | $ / shares							$ 1.59
Debt instrument, stated interest rate							2.11%
Proceeds from repayments of a nonrecourse promissory note | $								$ 2,100
Share-based compensation arrangement by share-based payment award, equity instruments other than options, nonvested, number									250,000
Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award
Common stock, shares authorized (in shares)				2,500,000,000					2,500,000,000	2,500,000,000
Common stock, par value (in dollars per share) | $ / shares		$ 0.0001							$ 0.0001	$ 0.0001
Common stock, voting rights, votes per share | vote		1
Class A Common Stock | IPO
Share-based Compensation Arrangement by Share-based Payment Award
Number of shares issued (in shares)				32,200,000
Price per share (in dollars per share) | $ / shares				$ 120.00
Net proceeds | $				$ 3,700,000
Class A Common Stock | Over-Allotment Option
Share-based Compensation Arrangement by Share-based Payment Award
Number of shares issued (in shares)				4,200,000
Class A Common Stock | Private Placement
Share-based Compensation Arrangement by Share-based Payment Award
Price per share (in dollars per share) | $ / shares				$ 120.00
Net proceeds | $				$ 500,000
Class A Common Stock | Private Placement | Salesforce Ventures LLC
Share-based Compensation Arrangement by Share-based Payment Award
Number of shares issued (in shares)				2,083,333
Class A Common Stock | Private Placement | Berkshire Hathaway Inc.
Share-based Compensation Arrangement by Share-based Payment Award
Number of shares issued (in shares)				2,083,333
Class A Common Stock | Employee stock purchase rights under the 2020 ESPP
Share-based Compensation Arrangement by Share-based Payment Award
Common stock reserved for future issuances (shares)				5,700,000
Class A Common Stock | 2020 Plan
Share-based Compensation Arrangement by Share-based Payment Award
Common stock reserved for future issuances (shares)				34,100,000
Maximum common shares authorized to be outstanding (shares)				78,816,888
Redeemable Convertible Preferred Stock
Share-based Compensation Arrangement by Share-based Payment Award
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)				(182,271,099)
Class B Common Stock
Share-based Compensation Arrangement by Share-based Payment Award
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)				182,271,099
Conversion ratio				1
Common stock, shares authorized (in shares)				355,000,000					185,461,432	355,000,000
Shares converted (in shares)	169,538,568	169,538,568
Common stock, par value (in dollars per share) | $ / shares		$ 0.0001							$ 0.0001	$ 0.0001
Common stock, voting rights, votes per share | vote			10
Shares issued (per share) | $ / shares													$ 38.77
Shares issued for common stock (shares)					8,600,000