Net Loss per Share Attributable to Common Stockholders - Schedule of Computation of Basic and Diluted Earnings per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss attributable to common stockholders	$ (26,468)	$ (40,853)	$ (85,349)	$ (77,673)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)	301,689	118,056	298,628	96,393
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.09)	$ (0.35)	$ (0.29)	$ (0.81)
Class A common stock | Common stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss attributable to common stockholders	$ (18,119)	$ (4,573)	$ (45,059)	$ (3,588)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)	206,528	13,215	157,656	4,453
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.09)	$ (0.35)	$ (0.29)	$ (0.81)
Class B common stock | Common stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss attributable to common stockholders	$ (8,349)	$ (36,280)	$ (40,290)	$ (74,085)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)	95,161	104,841	140,972	91,940
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.09)	$ (0.35)	$ (0.29)	$ (0.81)