Condensed Consolidated Statements of Convertible Preferred Stock And Stockholders' Equity (Deficit) - USD ($) shares in Thousands, $ in Thousands		Total	Convertible Preferred Stock	Convertible Preferred Stock Series D One Warrants	Convertible Preferred Stock Series H Preferred Stock	Convertible Preferred Stock Series G Preferred Stock	Class A and Class B Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit	Non- controlling Interest
Balance beginning (Shares) at Dec. 31, 2019			324,304				166,768
Balance beginning at Dec. 31, 2019		$ (112,949)	$ 187,191				$ 17	$ 101,671	$ 39	$ (239,036)	$ 24,360
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercises of stock option (in shares)							15,346
Issuance of common stock upon exercises of stock options		6,125					$ 1	6,124
Stock- based compensation		49,666						49,666
Others		59							59
Cumulative translation adjustments		(1)							(1)		0
Net loss		(147,140)								(145,900)	(1,240)
Issuance of preferred stock, net (in shares)						23,645
Issuance of preferred stock, net						$ 149,669
Conversion of convertible preferred stock to common stock in connection with the direct listing		0
Series D-1 warrants upon exercise of warrants for cash (in shares)	[1]			1,574
Series D-1 warrants upon exercise of warrants for cash	[1]			$ 8,225
Balance ending (Shares) at Jun. 30, 2020			349,523				182,114
Balance ending at Jun. 30, 2020		(204,240)	$ 345,085				$ 18	157,461	97	(384,936)	23,120
Balance beginning (Shares) at Mar. 31, 2020			349,523				170,357
Balance beginning at Mar. 31, 2020		(144,070)	$ 345,085				$ 17	145,211	255	(313,415)	23,862
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercises of stock option (in shares)							11,757
Issuance of common stock upon exercises of stock options		4,842					$ 1	4,841
Stock- based compensation		7,409						7,409
Others		(157)							(157)
Cumulative translation adjustments		(1)							(1)		0
Net loss		(72,263)								(71,521)	(742)
Balance ending (Shares) at Jun. 30, 2020			349,523				182,114
Balance ending at Jun. 30, 2020		(204,240)	$ 345,085				$ 18	157,461	97	(384,936)	23,120
Balance beginning (Shares) at Dec. 31, 2020			337,235				201,327
Balance beginning at Dec. 31, 2020		$ (232,381)	$ 344,827				$ 20	239,792	90	(492,290)	20,007
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercises of stock option (in shares)		24,139					24,139
Issuance of common stock upon exercises of stock options		$ 41,889					$ 2	41,887
Stock- based compensation		132,403						132,403
Release of restricted stock units (in shares)							4
Others (in shares)							1
Cumulative translation adjustments		48							24		24
Net loss		(279,033)								(274,351)	(4,682)
Issuance of preferred stock, net (in shares)					11,889
Issuance of preferred stock, net					$ 534,286
Conversion of convertible preferred stock to common stock in connection with the direct listing (in shares)			(349,124)				349,124
Conversion of convertible preferred stock to common stock in connection with the direct listing		879,113	$ (879,113)				$ 35	879,078
Balance ending (Shares) at Jun. 30, 2021							574,595
Balance ending at Jun. 30, 2021		542,039					$ 57	1,293,160	114	(766,641)	15,349
Balance beginning (Shares) at Mar. 31, 2021			0				568,894
Balance beginning at Mar. 31, 2021		591,594	$ 0				$ 57	1,199,833	90	(626,507)	18,121
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercises of stock option (in shares)							5,696
Issuance of common stock upon exercises of stock options		11,668					$ 0	11,668
Stock- based compensation		81,659						81,659
Release of restricted stock units (in shares)							4
Others (in shares)							1
Cumulative translation adjustments		48							24		24
Net loss		(142,930)								(140,134)	(2,796)
Balance ending (Shares) at Jun. 30, 2021							574,595
Balance ending at Jun. 30, 2021		$ 542,039					$ 57	$ 1,293,160	$ 114	$ (766,641)	$ 15,349

[1] Exercise of warrants for gross proceeds of $0.1 million and a reclassification of warrant liability fair market value of $8.1 million as of the exercise date.