Stockholders' Equity - Schedule of Reserved Shares of Common Stock for Future Issuances (Details) shares in Thousands	Mar. 31, 2019 shares
Class Of Stock [Line Items]
Total reserved shares of common stock	38,743
Equity Incentive Plan
Class Of Stock [Line Items]
Common stock awards granted under equity incentive plans	18,459
Employee Stock Purchase Plan
Class Of Stock [Line Items]
Common stock awards available for issuance	2,089
2017 Plan
Class Of Stock [Line Items]
Common stock awards available for issuance	18,195