Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Redeemable Convertible Preferred Stock	Common Stock	Common Stock Class A and Class B Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2016		144,778,000
Beginning balance at Dec. 31, 2016		$ 2,238,770
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of Series G redeemable convertible preferred stock, net of issuance cost (in shares)		18,662,000
Issuance of Series G redeemable convertible preferred stock, net of issuance cost		$ 599,715
Issuance of Series H redeemable convertible preferred stock, net of issuance cost (in shares)		36,375,000
Issuance of Series H redeemable convertible preferred stock, net of issuance cost		$ 1,445,564
Ending balance (in shares) at Dec. 31, 2017		199,815,000
Ending balance at Dec. 31, 2017		$ 4,284,049
Beginning balance (in shares) at Dec. 31, 2016			18,734,000
Beginning balance at Dec. 31, 2016	$ (1,303,730)		$ 0		$ 42,057	$ (1,345,694)	$ (93)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)			1,181,000
Issuance of common stock upon exercise of stock options	3,864				3,864
Issuance of restricted common stock upon early exercise of stock options (in shares)			3,000
Repurchase of common stock (in shares)			(2,000)
Vesting of early exercised stock options	101				101
Stock-based compensation	9,546				9,546
Other comprehensive income (loss)	(918)						(918)
Net loss	(688,301)					(688,301)
Ending balance (in shares) at Dec. 31, 2017			19,916,000
Ending balance at Dec. 31, 2017	$ (1,979,438)		$ 0		55,568	(2,033,995)	(1,011)
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of Series H redeemable convertible preferred stock, net of issuance cost (in shares)		6,397,000
Issuance of Series H redeemable convertible preferred stock, net of issuance cost		$ 254,162
Issuance of Series I redeemable convertible preferred stock, net of issuance cost (in shares)		12,429,000
Issuance of Series I redeemable convertible preferred stock, net of issuance cost		$ 588,496
Issuance of Series I redeemable convertible preferred stock issued as consideration as part of a business combination (in shares)		535,000
Issuance of Series I redeemable convertible preferred stock issued as consideration as part of a business combination		$ 25,340
Ending balance (in shares) at Dec. 31, 2018	219,175,709	219,176,000
Ending balance at Dec. 31, 2018	$ 5,152,047	$ 5,152,047
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)			2,254,000
Issuance of common stock upon exercise of stock options	9,564				9,564
Issuance of restricted common stock upon early exercise of stock options (in shares)			27,000
Issuance of restricted stock awards granted in conjunction with a business combination (in shares)			241,000
Vesting of early exercised stock options	207				207
Stock-based compensation	8,577				8,577
Other comprehensive income (loss)	1,144						1,144
Net loss	$ (911,335)					(911,335)
Ending balance (in shares) at Dec. 31, 2018	22,438,472		22,438,000
Ending balance at Dec. 31, 2018	$ (2,871,281)		$ 0		73,916	(2,945,330)	133
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering (in shares)		(219,176,000)
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering		$ (5,152,047)
Ending balance (in shares) at Dec. 31, 2019	0	0
Ending balance at Dec. 31, 2019	$ 0	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	10,856,000			10,855,000
Issuance of common stock upon exercise of stock options	$ 18,336				18,336
Issuance of common stock upon settlement of RSUs (in shares)				28,622,000
Issuance of common stock under employee stock purchase plan (in shares)				404,000
Issuance of common stock under employee stock purchase plan	14,767				14,767
Shares withheld related to net share settlement (in shares)				(14,394,000)
Shares withheld related to net share settlement	(942,982)				(942,982)
Issuance of common stock in connection with initial public offering, net of offering costs, underwriting discounts and commissions (in shares)				35,497,000
Issuance of common in connection with initial public offering, net of offering costs, underwriting discounts and commissions	2,483,623			$ 1	2,483,622
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering (in shares)				219,176,000
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering	5,152,047			$ 2	5,152,045
Canceled escrow shares related to a business combination (in shares)				(2,000)
Canceled escrow shares related to business combination	(90)				(90)
Vesting of early exercised stock options	2				2
Stock-based compensation	1,599,311				1,599,311
Other comprehensive income (loss)	2,592						2,592
Net loss	$ (2,602,241)					(2,602,241)
Ending balance (in shares) at Dec. 31, 2019	0			302,596,000
Ending balance at Dec. 31, 2019	$ 2,854,084			$ 3	$ 8,398,927	$ (5,547,571)	$ 2,725