Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Discount rate on goodwill (as a percent) Goodwill, Measurement Input Goodwill, Measurement Input Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss Award Timing Predetermined Award Timing Predetermined [Flag] Related Party Transaction [Axis] Related Party Transaction [Axis] Indefinite-Lived Intangible Assets [Axis] Indefinite-Lived Intangible Assets [Axis] Entity File Number Entity File Number Additional Paid in Capital Additional Paid-in Capital [Member] Tabular List, Table Tabular List [Table Text Block] Accounting Pronouncements Not Yet Adopted New Accounting Pronouncements, Policy [Policy Text Block] Illumina, Inc. Illumina, Inc. [Member] Illumina, Inc. Schedule of related party transactions Schedule of Related Party Transactions [Table Text Block] Accounts payable Increase (Decrease) in Accounts Payable Type of Restructuring [Domain] Type of Restructuring [Domain] Goodwill [Line Items] Goodwill [Line Items] Gross Unrealized Losses Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Net loss per share—basic (in dollars per share) Basic (in dollars per share) Earnings Per Share, Basic Adjustment to Compensation: Adjustment to Compensation [Axis] RELATED PARTY TRANSACTIONS Related Party Transactions Disclosure [Text Block] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Common stock reserved for future issuance (in shares) Common Stock, Capital Shares Reserved for Future Issuance REVENUE Revenue from Contract with Customer [Text Block] Discount Rate Measurement Input, Discount Rate [Member] 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purchase common stock Share-Based Payment Arrangement, Option [Member] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Grantee Status [Domain] Grantee Status [Domain] Accounts and Financing Receivables [Table] Accounts and Financing Receivables [Table] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Total stockholders’/member’s equity Beginning balance Ending balance Equity, Attributable to Parent Insider Trading Policies and Procedures [Line Items] Stock-based compensation expense, before taxes Stock-based compensation Share-Based Payment Arrangement, Expense Common stock, shares authorized (in shares) Common Stock, Shares Authorized Goodwill and Intangible Assets Disclosure [Abstract] Current assets: Assets, Current [Abstract] Total liabilities and stockholders’/member's equity Liabilities and Equity Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Liabilities and stockholders’/member’s equity Liabilities and Equity [Abstract] State Jurisdiction State and Local Jurisdiction [Member] Employee Stock Ownership Plan (ESOP) [Table] Employee Stock Ownership Plan (ESOP) [Table] Cover [Abstract] Total cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Cost of revenue — amortization of intangible assets Cost, Amortization Stock-based compensation expense, net of taxes Share-Based Payment Arrangement, Expense, after Tax General and administrative General and administrative General and Administrative Expense [Member] Finite-Lived intangible asset, useful life (in years) Finite-Lived Intangible Asset, Useful Life Accounting Policies [Abstract] Unrealized loss position Debt Securities, Available-for-Sale, Unrealized Loss Position Net Intangible Assets Finite-Lived Intangible Assets, Net Concentration Risk Type [Domain] Concentration Risk Type [Domain] Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Pay vs Performance Disclosure [Line Items] Foreign currency translation adjustment Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Loss before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Entity Shell Company Entity Shell Company Other non-current liabilities Other Liabilities, Noncurrent Goodwill impairment Goodwill, Impairment Loss Statement of Stockholders' Equity [Abstract] Balance Sheet Components [Abstract] Balance Sheet Components Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Company Selected Measure Amount Company Selected Measure Amount Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Comprehensive loss Comprehensive Income (Loss), Net of Tax, Attributable to Parent Issuance of common stock in connection with the Spin-Off and reclassification of contribution from member, net (in shares) Stock Issued During Period, Shares, New Issues, Spinoff Transaction Stock Issued During Period, Shares, New Issues, Spinoff Transaction Measurement Input Type [Axis] Measurement Input Type [Axis] Name Measure Name Screening revenue Screening Screening Revenue [Member] Screening Revenue Stock-based compensation expense Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block] Amortization of discount on marketable securities Investment Income, Net, Amortization of Discount and Premium Operating lease liabilities, current portion Operating Lease, Liability, Current Proceeds from maturities of marketable securities Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-Sale SDG Ops, LLC SDG Ops, LLC [Member] SDG Ops, LLC Consolidation, Less-than-Wholly-Owned Subsidiary, Parent Ownership Interest, Effect of Change [Table] Consolidation, Less-than-Wholly-Owned Subsidiary, Parent Ownership Interest, Effect of Change [Table] Deferred tax liability, net Deferred Income Tax Liabilities, Net Document Fiscal Period Focus Document Fiscal Period Focus Award Timing Method Award Timing Method [Text Block] Award Type [Axis] Award Type [Axis] Legal Entity [Axis] Legal Entity [Axis] Total assets Assets 2026 Finite-Lived Intangible Asset, Expected Amortization, Year One Trading Symbol Trading Symbol Released (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value 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Stock Units (RSUs) Restricted Stock Units (RSUs) [Member] Statement of Income Location, Balance [Domain] Statement of Income Location, Balance [Domain] Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Tranche Four Share-Based Payment Arrangement, Tranche Four [Member] Share-Based Payment Arrangement, Tranche Four Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items] Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items] 2029 Finite-Lived Intangible Asset, Expected Amortization, Year Four Entity Emerging Growth Company Entity Emerging Growth Company Employee Stock Ownership Plan (ESOP) Disclosures [Line Items] Employee Stock Ownership Plan (ESOP) Disclosures [Line Items] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Contribution from member, net Member's Equity, Increase From Member's Contribution Member's Equity, Increase From Member's Contribution Level 2 Fair Value, Inputs, Level 2 [Member] Former Employee Former Employee [Member] Former Employee Restructuring Reserve [Roll Forward] Restructuring Reserve [Roll Forward] Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Beginning balance Ending balance Indefinite-Lived Intangible Assets (Excluding Goodwill) Related Party Related Party [Member] Common stock, shares outstanding (in shares) Beginning balance (in shares) Ending balance (in shares) Common Stock, Shares, Outstanding Credit loss expense Accounts Receivable, Credit Loss Expense (Reversal) Plan Name [Axis] Plan Name [Axis] PEO PEO [Member] Disaggregation of revenue Disaggregation of Revenue [Table Text Block] Severance and related benefit costs Severance and 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in accrued liabilities as of June 30, 2025 Accrued liabilities Accrued Liabilities, Current Grail RSUs (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number Commitments and Contingencies Disclosure [Abstract] Cash flows from investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] General and administrative Operating expenses—General and administrative General and Administrative Expense Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Net cash used in operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Related Party Transactions [Abstract] Member’s Equity Member's Capital [Member] Member's Capital Estimated Fair Value Debt Securities, Available-for-Sale, Excluding Accrued Interest Laboratory supplies and research collaborations Laboratory Supplies And Research Collaborations Expense 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Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Customer B Customer B [Member] Customer B Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Ownership [Domain] Ownership [Domain] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Amortization of intangibles assets Amortization of Intangible Assets Amortization of Intangible Assets Depreciation and intangible assets amortization expense Depreciation, Depletion and Amortization Other non-current assets Other Assets, Noncurrent Customer [Domain] Customer [Domain] Entity Central Index Key Entity Central Index Key PEO Name PEO Name Transition Incentive Award Transition Incentive Award [Member] Transition Incentive Award Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of 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of Revenue [Line Items] Disaggregation of Revenue [Line Items] Compensation Amount Outstanding Recovery Compensation Amount Expected dividend Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Dividend Rate Statement of Comprehensive Income [Abstract] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Name Awards Close in Time to MNPI Disclosures, Individual Name Percentage of shares retained after spin-off (as a percent) Equity Ownership, Excluding Consolidated Entity and Equity Method Investee, Percentage Cash payments made Payments for Restructuring Outstanding, beginning balance (in dollars per share) Outstanding, ending balance (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Restricted cash Restricted Cash, Noncurrent Restructuring Type [Axis] Restructuring Type [Axis] Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Employee stock purchase plan Employee Stock [Member] Revenue: Revenue: Revenues [Abstract] Stock-based compensation expense APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] In-process Research and Development (IPR&D) In Process Research and Development [Member] Accumulated other comprehensive income Accumulated Other Comprehensive Income (Loss), Net of Tax Sales and marketing Selling and Marketing Expense Financial Instruments [Domain] Financial Instruments [Domain] Change in net unrealized gain on marketable securities OCI, Debt Securities, 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Securities Amount Development services revenue Development Services Developmental Services Revenue [Member] Developmental Services Revenue Equity Component [Domain] Equity Component [Domain] Document Period End Date Document Period End Date PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Cash and Cash Equivalents [Domain] Cash and Cash Equivalents [Domain] TAXES Income Tax Disclosure [Text Block] BALANCE SHEET COMPONENTS Supplemental Balance Sheet Disclosures [Text Block] Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Aggregate potential fair value Share-Based Compensation Arrangement By Share-Based Payment Award, Equity Instruments Other Than Options, Aggregate Potential Fair Value Share-Based Compensation Arrangement By Share-Based Payment Award, Equity Instruments Other Than Options, Aggregate Potential 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Payments to Acquire Property, Plant, and Equipment Name Forgone Recovery, Individual Name Total current assets Assets, Current Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Commercial Commercial [Member] Commercial Represented by: Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation [Abstract] Recognition of deferred tax liability in connection with the Spin-Off Stockholder's Equity, Decrease For Tax Liability Due To Spin-Off Transaction Stockholder's Equity, Decrease For Tax Liability Due To Spin-Off Transaction Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Purchase price as a percentage of fair value Share-Based Compensation Arrangement by Share-Based Payment Award, Purchase Price of Common Stock, Percent Reclassification of 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compensation expenses Employee-related Liabilities, Current GRAIL 2024 Cash-Based Equity Awards Program Grail, Inc. 2024 Cash-Based Equity Awards Program [Member] Grail, Inc. 2024 Cash-Based Equity Awards Program Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Table] Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Table] Trade Names Trade Names [Member] Shares owned (in shares) Investment Owned, Balance, Shares Net loss Net loss Net loss Net Income (Loss) Attributable to Parent Expiration Date Trading Arrangement Expiration Date Accrued other expenses Other Accrued Liabilities, Current Product Information [Line Items] Product Information [Line Items] Property and equipment, net Property, Plant and Equipment, Net Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Restructuring charges (adjustments), net Restructuring Charges Preferred stock, shares authorized (in shares) Preferred Stock, Shares 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Professional Fees, Current