Stockholders’ Equity - Schedule of Shares of Common Stock Reserved for Future Issuance (Details) - shares shares in Thousands	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Total	29,709	80,539
Outstanding options to purchase common stock
Class of Stock [Line Items]
Total	14,020	17,571
Outstanding restricted stock units
Class of Stock [Line Items]
Total	5,208	1,827
Restricted stock awards subject to repurchase
Class of Stock [Line Items]
Total	736	0
Estimated shares for future ESPP purchase
Class of Stock [Line Items]
Total	890	0
Available for future issuance
Class of Stock [Line Items]
Total	8,160	1,741
Redeemable convertible preferred stock
Class of Stock [Line Items]
Total	0	58,615
Outstanding warrants to purchase common stock
Class of Stock [Line Items]
Total	695	785