Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue	$ 499,744	$ 955,598	$ 1,794,801	$ 2,598,890
Costs and expenses
Cost of revenue	261,614	580,714	1,055,388	1,673,707
Operations and support	123,136	149,794	355,528	489,004
Research and development	232,106	288,272	693,946	1,229,065
Sales and marketing	78,548	163,858	326,807	619,938
General and administrative	257,693	263,820	718,087	907,842
Total costs and expenses	953,097	1,446,458	3,149,756	4,919,556
Loss from operations	(453,353)	(490,860)	(1,354,955)	(2,320,666)
Interest expense	(12,529)	0	(20,573)	0
Other income (expense), net	7,474	29,292	38,766	78,760
Loss before income taxes	(458,408)	(461,568)	(1,336,762)	(2,241,906)
Provision (benefit) for income taxes	1,109	1,909	(42,060)	4,283
Net loss	$ (459,517)	$ (463,477)	$ (1,294,702)	$ (2,246,189)
Net loss per share, basic and diluted (in dollars per share)	$ (1.46)	$ (1.57)	$ (4.18)	$ (11.05)
Weighted-average number of shares outstanding used to compute net loss per share, basic and diluted (in shares)	314,530	294,784	309,433	203,199
Cost of revenue
Stock-based compensation included in costs and expenses:
Stock-based compensation expense	$ 7,021	$ 12,078	$ 21,201	$ 68,625
Operations and support
Stock-based compensation included in costs and expenses:
Stock-based compensation expense	5,310	8,553	10,942	68,178
Research and development
Stock-based compensation included in costs and expenses:
Stock-based compensation expense	96,212	153,830	243,993	842,954
Sales and marketing
Stock-based compensation included in costs and expenses:
Stock-based compensation expense	6,910	7,969	16,115	65,213
General and administrative
Stock-based compensation included in costs and expenses:
Stock-based compensation expense	$ 51,264	$ 59,746	$ 140,247	$ 349,930