Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Redeemable Convertible Preferred Stock	Common Stock	Common Stock Common Class A And B	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2017	$ (1,979,438)				$ 55,568	$ (2,033,995)	$ (1,011)
Beginning balance, shares at Dec. 31, 2017		199,815,000
Beginning balance at Dec. 31, 2017		$ 4,284,049
Beginning balance, shares at Dec. 31, 2017			19,916,000
Issuance of Series H redeemable convertible preferred stock, net of issuance cost		$ 54,193
Issuance of Series H redeemable convertible preferred stock, net of issuance cost, shares		1,364,000
Issuance of common stock upon exercise of stock options	1,169				1,169
Issuance of common stock upon exercise of stock options, shares			335,000
Vesting of early exercised stock options	13				13
Stock-based compensation	1,996				1,996
Other comprehensive income (loss)	(1,013)						(1,013)
Net loss	(234,339)					(234,339)
Ending balance at Mar. 31, 2018	(2,211,612)				58,746	(2,268,334)	(2,024)
Ending balance, shares at Mar. 31, 2018		201,179,000
Ending balance at Mar. 31, 2018		$ 4,338,242
Ending balance, shares at Mar. 31, 2018			20,251,000
Beginning balance at Dec. 31, 2017	(1,979,438)				55,568	(2,033,995)	(1,011)
Beginning balance, shares at Dec. 31, 2017		199,815,000
Beginning balance at Dec. 31, 2017		$ 4,284,049
Beginning balance, shares at Dec. 31, 2017			19,916,000
Other comprehensive income (loss)	799
Net loss	(413,242)
Ending balance at Jun. 30, 2018	(2,384,255)				63,194	(2,447,237)	(212)
Ending balance, shares at Jun. 30, 2018		217,895,000
Ending balance at Jun. 30, 2018		$ 5,091,418
Ending balance, shares at Jun. 30, 2018			21,261,000
Beginning balance at Mar. 31, 2018	(2,211,612)				58,746	(2,268,334)	(2,024)
Beginning balance, shares at Mar. 31, 2018		201,179,000
Beginning balance at Mar. 31, 2018		$ 4,338,242
Beginning balance, shares at Mar. 31, 2018			20,251,000
Issuance of Series H redeemable convertible preferred stock, net of issuance cost		$ 199,969
Issuance of Series H redeemable convertible preferred stock, net of issuance cost, shares		5,032,000
Issuance of Series I redeemable convertible preferred stock, net of issuance cost		$ 553,207
Issuance of Series I redeemable convertible preferred stock, net of issuance cost, shares		11,684,000
Issuance of common stock upon exercise of stock options	2,928				2,928
Issuance of common stock upon exercise of stock options, shares			1,005,000
Issuance of restricted common stock upon early exercise of stock options, Shares			5,000
Vesting of early exercised stock options	19				19
Stock-based compensation	1,501				1,501
Other comprehensive income (loss)	1,812						1,812
Net loss	(178,903)					(178,903)
Ending balance at Jun. 30, 2018	(2,384,255)				63,194	(2,447,237)	(212)
Ending balance, shares at Jun. 30, 2018		217,895,000
Ending balance at Jun. 30, 2018		$ 5,091,418
Ending balance, shares at Jun. 30, 2018			21,261,000
Beginning balance at Dec. 31, 2018	(2,871,281)				73,916	(2,945,330)	133
Beginning balance, shares at Dec. 31, 2018		219,175,709
Beginning balance at Dec. 31, 2018	$ 5,152,047	$ 5,152,047
Beginning balance, shares at Dec. 31, 2018	22,438,472			22,438,000
Issuance of common stock upon exercise of stock options	$ 1,599				1,599
Issuance of common stock upon exercise of stock options, shares				7,121,000
Issuance of common stock upon settlement of RSUs, shares				17,688,000
Shares withheld related to net share settlement	(785,004)				(785,004)
Shares withheld related to net share settlement, shares				(11,415,000)
Vesting of early exercised stock options	2				2
Stock-based compensation	859,486				859,486
Other comprehensive income (loss)	2,053						2,053
Net loss	(1,138,473)					(1,138,473)
Ending balance at Mar. 31, 2019	(3,931,618)				149,999	(4,083,803)	2,186
Ending balance, shares at Mar. 31, 2019		219,176,000
Ending balance at Mar. 31, 2019		$ 5,152,047
Ending balance, shares at Mar. 31, 2019				35,832,000
Beginning balance at Dec. 31, 2018	(2,871,281)				73,916	(2,945,330)	133
Beginning balance, shares at Dec. 31, 2018		219,175,709
Beginning balance at Dec. 31, 2018	$ 5,152,047	$ 5,152,047
Beginning balance, shares at Dec. 31, 2018	22,438,472			22,438,000
Other comprehensive income (loss)	$ 5,360
Net loss	(1,782,712)
Ending balance at Jun. 30, 2019	3,277,132			$ 3	7,999,678	(4,728,042)	5,493
Ending balance, shares at Jun. 30, 2019		0
Ending balance at Jun. 30, 2019	0
Ending balance, shares at Jun. 30, 2019				292,751,000
Beginning balance at Mar. 31, 2019	(3,931,618)				149,999	(4,083,803)	2,186
Beginning balance, shares at Mar. 31, 2019		219,176,000
Beginning balance at Mar. 31, 2019		$ 5,152,047
Beginning balance, shares at Mar. 31, 2019				35,832,000
Issuance of common stock upon exercise of stock options	940				940
Issuance of common stock upon exercise of stock options, shares				250,000
Issuance of common stock upon settlement of RSUs, shares				3,476,000
Shares withheld related to net share settlement	(80,076)				(80,076)
Shares withheld related to net share settlement, shares				(1,478,000)
Issuance of common stock in connection with initial public offering, net of offering costs, underwriting discounts and commissions	2,483,623			$ 1	2,483,622
Issuance of common stock in connection with initial public offering, net of offering costs, underwriting discounts and commissions, shares				35,497,000
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering	5,152,047			$ 2	5,152,045
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering, shares		(219,176,000)
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering		$ (5,152,047)
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering, shares				219,176,000
Cancelled escrow shares related to a business combination	(90)				(90)
Cancelled escrow shares related to a business combination, shares				(2,000)
Stock-based compensation	293,238				293,238
Other comprehensive income (loss)	3,307						3,307
Net loss	(644,239)					(644,239)
Ending balance at Jun. 30, 2019	3,277,132			$ 3	$ 7,999,678	$ (4,728,042)	$ 5,493
Ending balance, shares at Jun. 30, 2019		0
Ending balance at Jun. 30, 2019	$ 0
Ending balance, shares at Jun. 30, 2019				292,751,000