| Cover | May 07, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | May 7, 2020 |
| Entity Registrant Name | Denali Therapeutics Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-38311 |
| Entity Tax Identification Number | 46-3872213 |
| Entity Address, Address Line One | 161 Oyster Point Blvd. |
| Entity Address, City or Town | South San Francisco |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94080 |
| City Area Code | 650 |
| Written Communications | false |
| Local Phone Number | 866-8548 |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Title of 12(b) Security | Common Stock, par value $0.01 per share |
| Trading Symbol | DNLI |
| Security Exchange Name | NASDAQ |
| Entity Central Index Key | 0001714899 |
| Amendment Flag | false |
