CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Revenue	$ 271,940	$ 201,911
Costs and expenses:
Cost of revenue	99,232	73,694
Research and development	145,704	72,444
Sales and marketing	117,027	76,394
General and administrative	56,067	24,205
Total costs and expenses	418,030	246,737
Loss from operations	(146,090)	(44,826)
Interest income	7,151	4,059
Interest expense and other income (expense), net	(2,077)	(500)
Loss before provision for income taxes	(141,016)	(41,267)
Provision for income taxes	180	153
Net loss	$ (141,196)	$ (41,420)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.25)	$ (0.33)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)	576,302	127,346