Document and Entity Information |
Aug. 10, 2026 |
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| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Aug. 10, 2026 |
| Entity Registrant Name | BlossomHill Therapeutics, Inc. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-43435 |
| Entity Tax Identification Number | 85-1578711 |
| Entity Address Address Line 1 | 10255 Science Center Drive |
| Entity Address Address Line 2 | Suite 200 |
| Entity Address City Or Town | San Diego |
| Entity Address State Or Province | CA |
| Entity Address Postal Zip Code | 92121 |
| City Area Code | 858 |
| Local Phone Number | 732-3880 |
| 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 | BLSM |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Amendment Flag | false |
| Current Fiscal Year End Date | --12-31 |
| Entity Central Index Key | 0001839970 |
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- Definition End date of current fiscal year in the format --MM-DD. No definition available.
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- Definition For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period. The format of the date is YYYY-MM-DD. No definition available.
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- Definition The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'. No definition available.
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- Definition Address Line 1 such as Attn, Building Name, Street Name No definition available.
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- Definition Indicate if registrant meets the emerging growth company criteria. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Indicate if an emerging growth company has elected not to use the extended transition period for complying with any new or revised financial accounting standards. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Two-character EDGAR code representing the state or country of incorporation. No definition available.
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- Definition The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Local phone number for entity. No definition available.
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- Definition Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Title of a 12(b) registered security. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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