Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Investments in Marketable Securities Investment, Policy [Policy Text Block] Schedule of Debt Securities, Fair Value of U.S. Treasury Securities and Money Market Fund Debt Securities, Available-for-Sale [Table Text Block] Award Timing Predetermined Award Timing Predetermined [Flag] 2025 Lessee, Operating Lease, Liability, to be Paid, Remainder of Fiscal Year Entity File Number Entity File Number Additional paid-in capital Additional Paid-in Capital [Member] Research tax incentives Research And Development Expense, Tax Incentives Research And Development Expense, Tax Incentives Foreign currency translation changes Restructuring Reserve, Translation and Other Adjustment Vesting of ordinary shares Share-based Compensation Arrangement by Share-based Payment Award, Options and Restricted Stock Units, Aggregate Intrinsic Value, Vested Share-based Compensation Arrangement by Share-based Payment Award, 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Genmab License Agreement Revenue from Contract with Customer [Text Block] Subsidiary or Equity Method Investee, Sale of Stock by Subsidiary or Equity Investee [Table] Subsidiary or Equity Method Investee, Sale of Stock, Type [Table] Schedule of Segment Reporting Information, by Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Stock issued during period (in shares) Stock Issued During Period, Shares, Employee Stock Purchase Plans Adjustment to Compensation, Amount Adjustment to Compensation Amount Unamortized debt issuance costs and unamortized end of term charge Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net Share-based compensation expense Share-Based Payment Arrangement, Noncash Expense U.S. Treasury and government agency securities US Government Corporations and Agencies Securities [Member] Stock options Share-Based Payment Arrangement, Option [Member] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Income taxes paid Income Taxes Paid Antidilutive Securities [Axis] Antidilutive Securities [Axis] Total shareholders’ equity Beginning balance Ending balance Equity, Attributable to Parent Unrealized holding gain on available for sale securities during period, net of tax of $0.4 million in 2024 OCI, before Reclassifications, Net of Tax, Attributable to Parent Debt Securities, Available-for-Sale [Table] Debt Securities, Available-for-Sale [Table] Measurement Frequency [Axis] Measurement Frequency [Axis] Insider Trading Policies and Procedures [Line Items] Compensation expense recognized Share-based compensation Share-Based Payment Arrangement, Expense Schedule of Property and Equipment, Net Property, Plant and Equipment [Table Text Block] Ordinary shares, shares authorized (in shares) Common Stock, Shares Authorized Segment Reporting, Asset Reconciling Item [Line Items] Segment Reporting, Asset Reconciling Item [Line Items] Maximum number of undisclosed targets to research products Contract With Customer, Maximum Number Of Undisclosed Targets To Research Products Contract With Customer, Maximum Number Of Undisclosed Targets To Research Products Issuance of ordinary shares, net of issuance costs (in shares) Stock Issued During Period, Shares, New Issues Current assets: Assets, Current [Abstract] Forfeited (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures in Period Total liabilities and shareholders' equity Liabilities and Equity Fair Value, Recurring Fair Value, Recurring [Member] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Number of Shares Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding [Roll Forward] Liabilities and shareholders’ equity Liabilities and Equity [Abstract] Cover [Abstract] Money market fund, included in cash and cash equivalents, fair value Cash and Cash Equivalents, Fair Value Disclosure Reclassification adjustment for realized net gain on available for sale marketable securities included in net loss, net of tax Reclassification adjustments Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent Exercisable at end of period (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Weighted Average Exercise Price General and administrative General and Administrative Expense [Member] Accounting Policies [Abstract] Remaining shares reserved for issuance (in shares) Share Repurchase Program, Remaining Authorized, Number of Shares Thereafter Lessor, Operating Lease, Payment to be Received, after Year Four Lessor, Operating Lease, Payment to be Received, after Year Four Schedule of Lessee, Operating Lease, Liability, Maturity Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block] Restricted Stock Awards Restricted Stock [Member] Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Debt Instrument [Line Items] Debt Instrument [Line Items] 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] Total operating lease liabilities Operating Lease, Liability Foreign currency translation adjustment Foreign currency translation adjustments 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 Total Lessor, Operating Lease, Payment to be Received Liabilities: Liabilities [Abstract] 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 Total principal payments, including End of Term Charge Long-Term Debt, Gross And End Of Term Charge Long-Term Debt, Gross And End Of Term Charge Other non-current liabilities Other Liabilities, Noncurrent Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Shareholders’ equity: Statement of Stockholders' Equity [Abstract] Statement of Cash Flows [Abstract] Company Selected Measure Amount Company Selected Measure Amount 2028 Lessee, Operating Lease, Liability, to be Paid, Year Three Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Total comprehensive loss Comprehensive Income (Loss), Net of Tax, Attributable to Parent Long-term investments Debt Securities, Available-for-Sale, Excluding Accrued Interest, Noncurrent Name Measure Name Restructuring reserve Balance as of January 1, 2025 Balance as of June 30, 2025 Restructuring Reserve Schedule of Share-based Compensation Expense Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block] Amortization of discount of marketable securities Investment Income, Net, Amortization of Discount and Premium Secured Debt Secured Debt [Member] Operating lease Current portion of operating lease liabilities Less: current portion Operating Lease, Liability, Current Document Fiscal Period Focus Document Fiscal Period Focus Cash and cash equivalents and short-term investments Cash And Cash Equivalents And Investments Cash And Cash Equivalents And Investments Award Timing Method Award Timing Method [Text Block] Office furniture Furniture and Fixtures [Member] U.S. Treasury securities, amortized cost Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, after Allowance for Credit Loss Award Type [Axis] Award Type [Axis] Foreign currency translation adjustment: Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Loan and Security Agreement (carried at amortized cost) Long-Term Debt Total assets Assets Trading Symbol Trading Symbol 2029 Lessee, Operating Lease, Liability, to be Paid, Year Four Vested (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 Entity Address, City or Town Entity Address, City or Town Cash flows from operating activities: Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Other segment items Segment Reporting, Other Segment Item, Amount Effect of exchange rate on cash and cash equivalents Effect of Exchange Rate on Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation 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Outstanding, Number 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] Significant other observable inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Restructuring Reserve [Roll Forward] Restructuring Reserve [Roll Forward] Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Operating Leases Lessee, Operating Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract] Ordinary shares, shares outstanding (in shares) Beginning balance (in shares) Ending balance (in shares) Common Stock, Shares, Outstanding 2025 Lessor, Operating Lease, Payment to be Received, Remainder of Fiscal Year Plan Name [Axis] Plan Name [Axis] Document Information [Table] Document Information [Table] PEO PEO [Member] Severance-Related Employee Severance [Member] Interest and investment income Interest and investment income Investment Income, Interest American Depositary Shares American Depositary Shares [Member] American Depositary Shares Other R&D expenses: Other R&D Expenses [Abstract] Other R&D Expenses Income tax liability Accrued Income Taxes, Current Changes in operating assets and liabilities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Stock option exercises Stock Issued During Period, Value, Stock Options Exercised Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Expected stock price volatility Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate Accumulated Deficit Retained Earnings [Member] Prepaid expenses and other current assets Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Number of Shares Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Schedule of Accrued Expenses and Other Current Liabilities Schedule of Accrued Liabilities [Table Text Block] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restatement Determination Date Restatement Determination Date Share-Based Payment Arrangement [Abstract] Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Income Statement [Abstract] Income tax expense Income tax expense Income Tax Expense (Benefit) Research and development expenses Prepaid Research and Development Costs Prepaid Research and Development Costs Purchases of investments in marketable securities Payments to Acquire Marketable Securities Sale of Stock [Domain] Sale of Stock [Domain] Document Information [Line Items] Document Information [Line Items] Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Product and Service [Domain] Product and Service [Domain] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Property and equipment, at cost Property, Plant and Equipment, Gross 2028 Lessor, Operating Lease, Payment to be Received, Year Three Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Program Termination Restructuring and Related Activities Disclosure [Text Block] Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Proceeds from option exercises Proceeds from Stock Options Exercised City Area Code City Area Code Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] All Trading Arrangements All Trading Arrangements [Member] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Options vested and expected to vest at end of period, weighted-average remaining contractual term Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term Accrued expenses and other current liabilities Accrued expenses and other current liabilities Accrued Liabilities, Current Research and development expenses Accrued Research And Development Expense, Current Accrued Research And Development Expense, Current Unvested beginning balance (in shares) Unvested ending balance (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number Commitments and Contingencies Disclosure [Abstract] Maximum additional potential option exercise fee Revenue, Remaining Performance Obligation, Variable Consideration Amount Revenue, Remaining Performance Obligation, Variable Consideration Amount Cash flows from investing activities: Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] General and administrative General and administrative expenses General and Administrative Expense Unrecognized compensation expense related to unvested stock option awards Share-Based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount 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 Debt securities, available-for-sale, fair value Debt Securities, Available-for-Sale, Excluding Accrued Interest Potential additional development and sales milestone Revenue From Contract With Customer, Potential Additional Development, Regulatory And Sales Milestone Payments Revenue From Contract With Customer, Potential Additional Development, Regulatory And Sales Milestone Payments Schedule of Assumptions Used to Estimate Fair Value of Stock Option Awards Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Total operating lease cost Lease, Cost Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Schedule of Lease, Cost Lease, Cost [Table Text Block] PEO Total Compensation Amount PEO Total Compensation Amount Long-Term Debt, Type [Axis] Long-Term Debt, Type [Axis] Vested and expected to vest at end of period (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price Money Market fund Money Market Funds [Member] LockBody program expenses Research And Development Expense, Technology Platform Research And Development Expense, Technology Platform Equity Components [Axis] Equity Components [Axis] Entity Ex Transition Period Entity Ex Transition Period Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Sublease income Sublease Income Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Supplemental disclosure: Supplemental Cash Flow Information [Abstract] Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Entity Address, Country Entity Address, Country Other Performance Measure, Amount Other Performance Measure, Amount Weighted-Average Exercise Price Per Share Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Security, Excluded EPS Calculation [Table] 2026 Lessor, Operating Lease, Payment to be Received, Year One Total current liabilities Liabilities, Current Individual: Individual [Axis] Sublease Income Lessor, Operating Lease, Payment to be Received, Fiscal Year Maturity [Abstract] Other Other Assets, Current Research and development Research and Development Expense [Member] Net cash used in investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Genmab A/S Genmab A/S [Member] Genmab A/S Interest paid Interest Paid, Excluding Capitalized Interest, Operating Activity Document Fiscal Year Focus Document Fiscal Year Focus Basis of Presentation and Consolidation Basis of Accounting, Policy [Policy Text Block] Investments above with unrealized loss, gross unrealized losses Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, Before Tax, Without Accumulated Unrealized Loss Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, Before Tax, Without Accumulated Unrealized Loss Operating lease right-of-use assets Operating lease, right-of-use asset Operating Lease, Right-of-Use Asset Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Entity Interactive Data Current Entity Interactive Data Current Operating lease cost Operating Lease, Cost Plan Name [Domain] Plan Name [Domain] Expected weighted average recognition period Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Stock option exercises (in shares) Exercised (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period License and other revenue Revenue from Contract with Customer [Policy Text Block] Aggregate intrinsic value of exercisable Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Intrinsic Value Less: Segment Reconciliation [Abstract] Purchase obligation Purchase Obligation Segment Information Segment Reporting Disclosure [Text Block] Aggregate Intrinsic Value (in millions) Share-Based Compensation Arrangement By Share-Based Payment Award, Aggregate Intrinsic Value [Abstract] Share-Based Compensation Arrangement By Share-Based Payment Award, Aggregate Intrinsic Value Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] U.S. Treasury securities US Treasury Securities [Member] Long-Lived Tangible Asset [Axis] Long-Lived Tangible Asset [Axis] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Schedule of Lessor, Operating Lease, Liability, Maturity Lessor, Operating Lease, Payment to be Received, Maturity [Table Text Block] Deferred tax asset Deferred Income Tax Assets, Net Schedule of Reconciliation of Changes, Net of Applicable Income Taxes Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Depreciation and amortization Depreciation, Depletion and Amortization Other non-current assets Other Assets, Noncurrent Interest payable Interest Payable, Current Entity Central Index Key Entity Central Index Key PEO Name PEO Name Schedule of Maturities of Long-Term Debt Schedule of Maturities of Long-Term Debt [Table Text Block] License and other revenue License and other revenue Revenues Aggregate net proceeds from shares sold Sale of Stock, Consideration Received on Transaction 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 Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Arrangement Duration Trading Arrangement Duration Computer equipment Computer Equipment [Member] Segments [Axis] Segments [Axis] Investments above with no unrealized loss, amortized cost Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, After Allowance For Credit Loss, With Accumulated Unrealized Loss Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, After Allowance For Credit Loss, With Accumulated Unrealized Loss Prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Number of debt securities Number Of Debt Securities Number Of Debt Securities Exercise Price Award Exercise Price Entity Filer Category Entity Filer Category Local Phone Number Local Phone Number Class of Stock [Domain] Class of Stock [Domain] Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Unrecognized compensation expense excluding options Share-Based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount Share price (in dollars per share) Share Price Share-based Compensation Share-Based Payment Arrangement [Text Block] Assets Assets: Assets [Abstract] Long term debt Long-Term Debt, Excluding Current Maturities Credit Facility [Axis] Credit Facility [Axis] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Statement of Financial Position Location, Balance [Axis] Statement of Financial Position Location, Balance [Axis] Entity Address, Address Line Three Entity Address, Address Line Three Forfeited (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Fair Value Measurement Fair Value Disclosures [Text Block] Credit Facility [Domain] Credit Facility [Domain] Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Entity Address, Address Line One Entity Address, Address Line One 2021 Plan 2021 Plan [Member] 2021 Plan Entity Address, Address Line Two Entity Address, Address Line Two Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Shares withheld to pay employee withholding tax on share-based compensation (in shares) Share-Based Payment Arrangement, Shares Withheld for Tax Withholding Obligation Operating lease liabilities Operating lease liabilities, net of current portion Lease liabilities, net of current portion Operating Lease, Liability, Noncurrent Fair Value as of Grant Date Award Grant Date Fair Value Entity Registrant Name Entity Registrant Name Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Investments above with unrealized loss, amortized cost Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, After Allowance For Credit Loss, Without Accumulated Unrealized Loss Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, After Allowance For Credit Loss, Without Accumulated Unrealized Loss Personnel expenses Labor and Related Expense Granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period Forfeited (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period Document Quarterly Report Document Quarterly Report Total Assets, Fair Value Disclosure The fair value of LSA, classified as Level 2 under ASC Topic 820, Fair Value Measurement Long-Term Debt, Fair Value Number of debt securities, loss position Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Interest receivable Interest Receivable, Current Counterparty Name [Domain] Counterparty Name [Domain] Change in fair value of financial instruments Financial Instruments Gain (Loss) From Change In Fair Value Financial Instruments Gain (Loss) From Change In Fair Value Number of operating segments Number of Operating Segments 2027 Lessee, Operating Lease, Liability, to be Paid, Year Two Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Options outstanding, weighted-average remaining contractual term Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Schedule of Debt Schedule of Debt [Table Text Block] Granted (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Title Trading Arrangement, Individual Title Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Reportable Segment Reportable Segment [Member] Reportable Segment Restatement Determination Date: Restatement Determination Date [Axis] Non-PEO NEO Non-PEO NEO [Member] Aggregate intrinsic value of options Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Intrinsic Value Restructuring and Related Costs Restructuring and Related Costs [Table Text Block] Schedule of Prepaid Expenses and Other Current Assets Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Table Text Block] Other, net Proceeds from (Payment for) Other Financing Activity Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Sale of Stock [Axis] Sale of Stock [Axis] U.S. Treasury securities, gross unrealized gains Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax Name Trading Arrangement, Individual Name Award Type [Domain] Award Type [Domain] 2026 Lessee, Operating Lease, Liability, to be Paid, Year One Equity Awards Adjustments Equity Awards Adjustments [Member] Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Compensation Amount Outstanding Recovery Compensation Amount Purchase obligation, to be paid, within one year Purchase Obligation, to be Paid, Remainder of Fiscal Year Schedule of Replacement Equity Award Activity Share-Based Payment Arrangement, Activity [Table Text Block] Expected dividend yield Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Dividend Rate Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Sale of stock, consideration receivable (up to) Sale Of Stock, Maximum Consideration Receivable Sale Of Stock, Maximum Consideration Receivable MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Name Awards Close in Time to MNPI Disclosures, Individual Name Unvested beginning balance (in dollars per share) Unvested 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 Cash payments Payments for Restructuring Restructuring Type [Axis] Restructuring Type [Axis] Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Share-based compensation expense APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Accumulated other comprehensive income Accumulated Other Comprehensive Income (Loss), Net of Tax Country Region Country Region 2026 Long-Term Debt, Maturity, Year One Unrealized holding gain on available for sale securities during period, tax Other Comprehensive Income (Loss) before Reclassifications, Tax Financial Instruments [Domain] Financial Instruments [Domain] Unrealized (loss) gain on available for sale marketable securities, net of reclassification adjustment and tax OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment and Tax Segments [Domain] Segments [Domain] Income Statement Location [Axis] Statement of Income Location, Balance [Axis] Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Statement of Financial Position Location, Balance [Domain] Statement of Financial Position Location, Balance [Domain] Amortization of debt issuance costs and exit fee of long-term debt Amortization of Debt Issuance Costs and Discounts Unrealized gain on available for sale securities: AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member] Less: Accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Company Selected Measure Name Company Selected Measure Name Debt Debt Disclosure [Text Block] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Accounts payable Accounts Payable, Current Operating lease payments reducing operating lease liabilities Operating Lease, Payments Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] All Executive Categories All Executive Categories [Member] Ordinary shares: £0.002 nominal value: 222,480,776 shares authorized, 133,913,556 issued and outstanding at June 30, 2025: 184,469,623 shares authorized, 132,631,587 issued and outstanding at December 31, 2024 Common Stock, Value, Issued Short-term investments Short-Term Investments Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Tax incentive receivable Increase (Decrease) In Tax Incentive Receivables Increase (Decrease) In Tax Incentive Receivables Weighted average ordinary shares outstanding - diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Commitments and contingencies (Note 7) Commitments and Contingencies Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Reconciliation of Assets from Segment to Consolidated [Table] Reconciliation of Assets from Segment to Consolidated [Table] Entity Small Business Entity Small Business End of term charge Long-Term Debt, Gross, End Of Term Charge Long-Term Debt, Gross, End Of Term Charge Entity Transition Report Document Transition Report Short-term investments Short-Term Investments [Member] Underlying Securities Award Underlying Securities Amount 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] Balance Sheet Components Supplemental Balance Sheet Disclosures [Text Block] Purchase obligation, to be paid, year one through five Purchase Obligation, to be Paid, Year One through Five Purchase Obligation, to be Paid, Year One through Five Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Revenue from Contract with Customer [Abstract] Investments above with no unrealized loss, gross unrealized gains Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, Before Tax, With Accumulated Unrealized Loss Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, Before Tax, With Accumulated Unrealized Loss Short term lease cost Short-Term Lease, Cost Options exercisable, weighted-average remaining contractual term Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Operating leases, net Increase (Decrease) in Operating Lease Liability Document Type Document Type Significant unobservable inputs (Level 3) Fair Value, Inputs, Level 3 [Member] Name Outstanding Recovery, Individual Name Additional paid-in capital Additional Paid in Capital Product and Service [Axis] Product and Service [Axis] Proceeds from issuance of shares under ATM program, net of issuance costs Proceeds from Issuance of Common Stock Variable lease cost Variable Lease, Cost All Individuals All Individuals [Member] Long-Term Debt, Type [Domain] Long-Term Debt, Type [Domain] Tax incentive receivable Tax Incentive Receivable, Current Tax Incentive Receivable, Current Contract Termination Contract Termination [Member] Fair Value Disclosures [Abstract] Purchases of property and equipment Payments to Acquire Property, Plant, and Equipment Vested and expected to vest at end of period (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number Name Forgone Recovery, Individual Name Reversal of charge Restructuring Reserve, Accrual Adjustment 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] Underwriter Offering Underwriter Offering [Member] Underwriter Offering Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Payment of employee withholding taxes related to withheld shares for stock based compensation plans Payment, Tax Withholding, Share-Based Payment Arrangement Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Other comprehensive (loss) income: Other Comprehensive Income (Loss), 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