Stockholders’ Equity - Schedule of Shares of Common Stock Reserved for Future Issuance (Details) - shares shares in Thousands	Mar. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Total	32,360	29,709
Outstanding options to purchase common stock
Class of Stock [Line Items]
Total	12,629	14,020
Outstanding restricted stock units
Class of Stock [Line Items]
Total	4,713	5,208
Restricted stock awards subject to repurchase
Class of Stock [Line Items]
Total	614	736
Estimated shares for future ESPP purchase
Class of Stock [Line Items]
Total	1,843	890
Available for future issuance under 2019 Plan
Class of Stock [Line Items]
Total	11,866	8,160
Outstanding warrants to purchase common stock
Class of Stock [Line Items]
Total	695	695