| Cover | Jun. 04, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Jun. 4, 2021 |
| Entity Registrant Name | ZENTALIS PHARMACEUTICALS, INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-39263 |
| Entity Tax Identification Number | 82-3607803 |
| Entity Address, Address Line One | 530 Seventh Avenue |
| Entity Address, Address Line Two | Suite 2201 |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10018 |
| City Area Code | 212 |
| Local Phone Number | 433-3791 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.001 par value per share |
| Trading Symbol | ZNTL |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Entity Central Index Key | 0001725160 |
| Amendment Flag | false |
