Net Loss per Share Attributable to Common Stockholders - Schedule of Basic and Diluted Net Loss per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Numerator:
Net loss available to Class A and Class B common stockholders	$ (53,863)	$ (42,512)	$ (78,752)	$ (118,461)
Denominator:
Weighted average shares used to compute net loss per share available to Class A and Class B common stockholders, basic (in shares)	172,749	125,928	171,753	124,823
Weighted average shares used to compute net loss per share available to Class A and Class B common stockholders, diluted (in shares)	172,749	125,928	171,753	124,823
Net loss per share attributable to Class A and Class B common stockholders, basic (in dollars per share)	$ (0.31)	$ (0.34)	$ (0.46)	$ (0.95)
Net loss per share attributable to Class A and Class B common stockholders, diluted (in dollars per share)	$ (0.31)	$ (0.34)	$ (0.46)	$ (0.95)