CONDENSED CONSOLIDATED STATEMENTS OF MEZZANINE EQUITY AND STOCKHOLDERS’ (DEFICIT) EQUITY - USD ($) $ in Thousands		Total	Redeemable convertible preferred stock	Series F	Series G	Common stock		Additional paid-in capital	Accumulated other comprehensive income	Accumulated deficit
Balance at beginning of period, Redeemable convertible preferred stock (in shares) at Dec. 31, 2019			321,626,778
Balance at beginning of period, Redeemable convertible preferred stock at Dec. 31, 2019			$ 912,411
Increase (decrease) in mazzanine equity
Issuance of convertible preferred stock, net of issuance costs (in shares)				48,000,000	43,116,119
Issuance of convertible preferred stock, net of issuance costs				$ 599,284	$ 668,066
Balance at end of period, Redeemable convertible preferred stock (in shares) at Sep. 30, 2020			412,742,897
Balance at end of period, Redeemable convertible preferred stock at Sep. 30, 2020			$ 2,179,761
Balance at beginning of period, Common stock (in shares) at Dec. 31, 2019						224,802,545
Balance at beginning of period at Dec. 31, 2019		$ (97,048)				$ 1		$ 99,439	$ 189	$ (196,677)
Increase (decrease) in stockholder's equity
Net loss		(5,579)								(5,579)
Shares issued in connection with employee stock plans (in shares)						1,883,789
Shares issued in connection with employee stock options		4,514						4,514
Vesting of early-exercised stock options		439						439
Repurchase of common stock (in shares)						(81,196)
Repurchase of common stock		(875)								(875)
Change in other comprehensive income		20							20
Share-based compensation		5,914						5,914
Balance at end of period, Common stock (in shares) at Sep. 30, 2020						226,605,138
Balance at end of period at Sep. 30, 2020		(92,615)				$ 1		110,306	209	(203,131)
Balance at beginning of period, Redeemable convertible preferred stock (in shares) at Jun. 30, 2020			366,266,778
Balance at beginning of period, Redeemable convertible preferred stock at Jun. 30, 2020			$ 1,469,708
Increase (decrease) in mazzanine equity
Issuance of convertible preferred stock, net of issuance costs (in shares)				3,360,000	43,116,119
Issuance of convertible preferred stock, net of issuance costs				$ 41,987	$ 668,066
Balance at end of period, Redeemable convertible preferred stock (in shares) at Sep. 30, 2020			412,742,897
Balance at end of period, Redeemable convertible preferred stock at Sep. 30, 2020			$ 2,179,761
Balance at beginning of period, Common stock (in shares) at Jun. 30, 2020						225,750,368
Balance at beginning of period at Jun. 30, 2020		(86,949)				$ 1		105,505	15	(192,470)
Increase (decrease) in stockholder's equity
Net loss		(10,661)								(10,661)
Shares issued in connection with employee stock plans (in shares)						865,966
Shares issued in connection with employee stock options		3,074						3,074
Vesting of early-exercised stock options		127						127
Repurchase of common stock (in shares)						(11,196)
Change in other comprehensive income		194							194
Share-based compensation		1,600						1,600
Balance at end of period, Common stock (in shares) at Sep. 30, 2020						226,605,138
Balance at end of period at Sep. 30, 2020		$ (92,615)				$ 1		110,306	209	(203,131)
Balance at beginning of period, Redeemable convertible preferred stock (in shares) at Dec. 31, 2020		412,742,897	412,742,897	48,000,000	43,116,119
Balance at beginning of period, Redeemable convertible preferred stock at Dec. 31, 2020		$ 2,179,739	$ 2,179,739	$ 599,284	$ 668,044
Balance at end of period, Redeemable convertible preferred stock (in shares) at Sep. 30, 2021		0	0
Balance at end of period, Redeemable convertible preferred stock at Sep. 30, 2021		$ 0	$ 0
Balance at beginning of period, Common stock (in shares) at Dec. 31, 2020		229,031,546				229,031,546	[1]
Balance at beginning of period at Dec. 31, 2020		$ (55,322)				$ 1	[1]	134,307	473	(190,103)
Increase (decrease) in stockholder's equity
Net loss		(3,263,165)							0	(3,263,165)
Shares issued in connection with employee stock plans (in shares)	[1]					5,819,965
Shares issued in connection with employee stock options		11,665				$ 24	[1]	11,641
Issuance of common stock in connection with initial public offering, net of issuance costs (in shares)	[1]					56,729,194
Issuance of common stock in connection with initial public offering, net of issuance costs		2,052,380				$ 6	[1]	2,052,374
Issuance of common stock upon settlement of restricted stock units, net of shares withheld (in shares)	[1]					13,759,434
Issuance of common stock upon settlement of restricted stock units, net of shares withheld		(411,772)						(411,772)
Vesting of early-exercised stock options		281						281
Conversion of preferred stock to common stock (in shares)			(412,742,897)			412,742,897	[1]
Conversion of preferred stock to common stock		2,179,739	$ (2,179,739)			$ 41	[1]	2,179,698
Conversion of convertible notes to common stock (in shares)	[1]					137,305,156
Conversion of convertible notes to common stock		5,217,597				$ 14	[1]	5,217,583
Reclassification of warrant liability to stockholders' equity		380,036						380,036
Vesting of replacement awards issued in connection with acquisition		639						639
Repurchase of common stock (in shares)	[1]					(3,110)
Change in other comprehensive income		(90)							(90)
Share-based compensation		$ 1,272,594						1,272,594
Balance at end of period, Common stock (in shares) at Sep. 30, 2021		0				855,385,082	[1]
Balance at end of period at Sep. 30, 2021		$ 7,384,582				$ 86	[1]	10,837,381	383	(3,453,268)
Balance at beginning of period, Redeemable convertible preferred stock (in shares) at Jun. 30, 2021			412,742,897
Balance at beginning of period, Redeemable convertible preferred stock at Jun. 30, 2021			$ 2,179,739
Balance at end of period, Redeemable convertible preferred stock (in shares) at Sep. 30, 2021		0	0
Balance at end of period, Redeemable convertible preferred stock at Sep. 30, 2021		$ 0	$ 0
Balance at beginning of period, Common stock (in shares) at Jun. 30, 2021	[2]					232,609,957
Balance at beginning of period at Jun. 30, 2021		(1,984,764)				$ 1	[2]	151,281	525	(2,136,571)
Increase (decrease) in stockholder's equity
Net loss		(1,316,697)								(1,316,697)
Shares issued in connection with employee stock plans (in shares)	[2]					2,238,444
Shares issued in connection with employee stock options		5,086				$ 24	[2]	5,062
Issuance of common stock in connection with initial public offering, net of issuance costs (in shares)	[2]					56,729,194
Issuance of common stock in connection with initial public offering, net of issuance costs		2,052,380				$ 6	[2]	2,052,374
Issuance of common stock upon settlement of restricted stock units, net of shares withheld (in shares)	[2]					13,759,434
Issuance of common stock upon settlement of restricted stock units, net of shares withheld		(411,772)						(411,772)
Vesting of early-exercised stock options		108						108
Conversion of preferred stock to common stock (in shares)			(412,742,897)			412,742,897	[2]
Conversion of preferred stock to common stock		2,179,739	$ (2,179,739)			$ 41	[2]	2,179,698
Conversion of convertible notes to common stock (in shares)	[2]					137,305,156
Conversion of convertible notes to common stock		5,217,597				$ 14	[2]	5,217,583
Reclassification of warrant liability to stockholders' equity		380,036						380,036
Vesting of replacement awards issued in connection with acquisition		639						639
Change in other comprehensive income		(142)							(142)
Share-based compensation		$ 1,262,372						1,262,372
Balance at end of period, Common stock (in shares) at Sep. 30, 2021		0				855,385,082	[1]
Balance at end of period at Sep. 30, 2021		$ 7,384,582				$ 86	[1]	$ 10,837,381	$ 383	$ (3,453,268)

[1] The share amounts listed above combine common stock, Class A common stock and Class B common stock. In connection with the completion of our initial public offering, all previously outstanding shares of common stock were reclassified into Class A common stock and Class B common stock. Refer to Note 1 for more information.

[2] The share amounts listed above combine common stock, Class A common stock and Class B common stock. In connection with the completion of our initial public offering, all previously outstanding shares of common stock were reclassified into Class A common stock and Class B common stock. Refer to Note 1 for more information.