Redeemable Convertible Preferred Stock - Narrative (Details)	1 Months Ended					12 Months Ended
	Sep. 30, 2020 USD ($) shares	Aug. 31, 2019 USD ($) $ / shares shares	Feb. 28, 2019 shares	Oct. 31, 2018 shares	Sep. 30, 2018 shares	Jan. 31, 2021 USD ($) member vote $ / shares shares	Jan. 31, 2020 USD ($) $ / shares shares	Jan. 31, 2019 shares	Jan. 31, 2018 shares
Class of Stock [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)						(182,271,099)
Conversion of redeemable convertible preferred stock to common stock upon initial public offering | $						$ 1,415,047,000
Conversion of redeemable convertible preferred stock to common stock upon initial public offering | $						$ (1,415,047,000)
Redeemable convertible preferred stock, shares outstanding (in shares)						0	169,921,272	168,309,042	138,947,468
Redeemable convertible preferred stock, shares issued (in shares)						0	169,921,272
Preferred stock, voting rights, votes per share (in dollars per share) | vote						10
Dividend rate (in percent)						8.00%
Dividends declared | $						$ 0	$ 0
Series G-1 Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Issuance of redeemable convertible preferred stock (in shares)						8,480,857
Issuance Price Per Share (in dollars per share) | $ / shares						$ 38.77
Series G-2 Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Issuance of redeemable convertible preferred stock (in shares)						3,868,970
Series F Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Issuance of redeemable convertible preferred stock (in shares)			850,118
Series F Redeemable Convertible Preferred Stock | Chief Financial Officer
Class of Stock [Line Items]
Issuance of redeemable convertible preferred stock (in shares)		762,112		29,227,556
Proceeds from issuance of temporary equity | $		$ 11,400,000
Series E Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Issuance of redeemable convertible preferred stock (in shares)					134,018
Class B Common Stock
Class of Stock [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)	182,271,099
Conversion of redeemable convertible preferred stock to common stock upon initial public offering | $	$ 1,400,000,000
Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)	(182,271,099)
Conversion of redeemable convertible preferred stock to common stock upon initial public offering | $	$ (1,400,000,000)
Redeemable convertible preferred stock, shares outstanding (in shares)							169,921,272
Redeemable convertible preferred stock, shares issued (in shares)							169,921,272
Class A Common Stock | Maximum
Class of Stock [Line Items]
Preferred stock, proceeds issued upon conversion | $						$ 300,000,000.0
Series A Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, number of shares outstanding required for voting rights (in shares)						4,000,000
Preferred stock, number of shares outstanding required for voting rights | member						1
Series B Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, number of shares outstanding required for voting rights (in shares)						4,000,000
Preferred stock, number of shares outstanding required for voting rights | member						1
Class A and Class B Common Stock
Class of Stock [Line Items]
Common stock, voting rights, number of members entitled to vote | member						2
Series F
Class of Stock [Line Items]
Issuance Price Per Share (in dollars per share) | $ / shares		$ 14.96125					$ 14.96125
Redeemable convertible preferred stock, shares outstanding (in shares)							30,839,786
Redeemable convertible preferred stock, shares issued (in shares)							30,839,786