Net Loss per Share - Schedule of Computation of Net Loss per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerator:
Net loss	$ (53,276)	$ (67,323)	$ (129,582)	$ (142,698)
Denominator:
Weighted average shares used in computing net loss per share, basic and diluted (shares)	221,352	204,109	219,570	201,001
Net loss per share—basic and diluted (in usd per share)	$ (0.24)	$ (0.33)	$ (0.59)	$ (0.71)