STOCK-BASED COMPENSATION - Schedule of ESPP fair value assumptions (Details) - Employee stock purchase plan - The GRAIL, Inc. 2024 Employee Stock Purchase Plan - $ / shares |
3 Months Ended | 9 Months Ended |
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Sep. 30, 2025 |
Sep. 30, 2025 |
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| Employee Stock Ownership Plan (ESOP) Disclosures [Line Items] | ||
| Expected life (in years) | 6 months | 6 months |
| Risk-free interest rate | 4.20% | 4.20% |
| Expected volatility | 108.70% | 108.70% |
| Expected dividend | 0.00% | |
| Weighted-average estimated grant date fair value per share (in dollars per share) | $ 17.68 | $ 17.68 |
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Rate of weighted-average expected volatility for award under share-based payment arrangement. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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