Net Loss per Share Available to Common Stockholders - Schedule of Basic and Diluted Net Loss per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Numerator:
Net loss attributable to Class A and Class B common stockholders	$ (164,445)	$ (157,553)	$ (304,414)
Deemed dividend	0	0	(2,454)
Net loss available to Class A and Class B common stockholders	$ (164,445)	$ (157,553)	$ (306,868)
Denominator:
Weighted average shares used to compute net loss per share available to Class A and Class B common stockholders, basic (in shares)	173,438	138,722	115,118
Weighted average shares used to compute net loss per share available to Class A and Class B common stockholders, diluted (in shares)	173,438	138,722	115,118
Net loss per share attributable to Class A and Class B common stockholders, basic (in dollars per share)	$ (0.95)	$ (1.14)	$ (2.67)
Net loss per share attributable to Class A and Class B common stockholders, diluted (in dollars per share)	$ (0.95)	$ (1.14)	$ (2.67)