| Document and Entity Information | Mar. 18, 2022 |
| Cover [Abstract] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001620463 |
| Document Type | 8-K |
| Document Period End Date | Mar. 18, 2022 |
| Entity Registrant Name | Athira Pharma, Inc. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-39503 |
| Entity Tax Identification Number | 45-3368487 |
| Entity Address, Address Line One | 18706 North Creek Parkway |
| Entity Address, Address Line Two | Suite 104 |
| Entity Address, City or Town | Bothell |
| Entity Address, State or Province | WA |
| Entity Address, Postal Zip Code | 98011 |
| City Area Code | (206) |
| Local Phone Number | 221-8112 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $0.0001 par value per share |
| Trading Symbol | ATHA |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
