| Document and Entity Information | Feb. 28, 2022 |
| Document and Entity Information [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Feb. 28, 2022 |
| Entity File Number | 001-39712 |
| Entity Registrant Name | Olema Pharmaceuticals, Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 30-0409740 |
| Entity Address, Address Line One | 512 2nd Street |
| Entity Address, Adress Line Two | 4th Floor |
| Entity Address, City or Town | San Francisco |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94107 |
| City Area Code | 415 |
| Local Phone Number | 651-3316 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.0001 par value per share |
| Trading Symbol | OLMA |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001750284 |
| Amendment Flag | false |
