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time bands [member] Corporate tax rate Applicable tax rate Total assets Assets Assets Assets [abstract] Basic, income / (loss) for the period attributable to equity holders (in CHF per share) Basic earnings (loss) per share Bottom of Range [Member] Bottom of range [member] Carrying amount, accumulated depreciation, amortization and impairment and gross carrying amount [axis] Carrying amount [member] Cash and cash equivalents [Abstract] Cash [abstract] Cash and cash equivalents Cash and cash equivalents, beginning of period Cash and cash equivalents, end of period Cash Company's cash position Cash and cash equivalents [Abstract] Net cash flows provided by financing activities Cash flows from (used in) financing activities Financing activities Cash flows from (used in) financing activities [abstract] Net cash flows used in investing activities Cash flows from (used in) investing activities Investing activities Cash flows from (used in) investing activities [abstract] Net cash flows 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[Member] IT Equipment [Member] Employer's contribution Employer's contributions Contributions to plan by employer, net defined benefit liability (asset) Employees' contributions Contributions to plan by plan participants, net defined benefit liability (asset) Credit Risk [Member] Credit risk [member] Foreign Currency Exchange Risk [Member] Currency risk [member] Accrued expenses Current accrued expenses and other current liabilities Accrued income Current accrued income Total current assets Current assets Current assets Current assets [abstract] Total current liabilities Current liabilities Current liabilities Current liabilities [abstract] Prepaid expenses Current prepaid expenses Prepaid expenses Current prepayments Total Current prepayments and current accrued income Accrued payroll expenses Current provisions for employee benefits Withholding tax Current receivables from taxes other than income tax Service cost Service cost Current service cost, net defined benefit liability 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statement of income Disclosure of net defined benefit liability (asset) [text block] Disclosure of net defined benefit liability (asset) [line items] Disclosure of net defined benefit liability (asset) [table] Post balance sheet events [Abstract] Disclosure of non-adjusting events after reporting period [abstract] Disclosure of non-adjusting events after reporting period [line items] Disclosure of non-adjusting events after reporting period [table] Summary of non-vested share awards (restricted share and restricted share units) Disclosure of number and weighted average exercise prices of other equity instruments [text block] Number and weighted average exercise prices of options for Plans A, B, and C1 Disclosure of number and weighted average exercise prices of share options [text block] Number and weighted average exercise prices of options under the share option programs [Abstract] Disclosure of number and weighted average remaining contractual life of outstanding share options [abstract] Capital risk management [Abstract] Capital risk management Disclosure of objectives, policies and processes for managing capital [text block] Segment reporting [Abstract] Disclosure of operating segments [abstract] Property, plant and equipment [Abstract] Property, plant and equipment Disclosure of property, plant and equipment [text block] Disclosure of detailed information about property, plant and equipment [line items] Disclosure of detailed information about property, plant and equipment [table] Related-party transactions Disclosure of related party [text block] Research and Development Disclosure of research and development expense [text block] Financial Assets Disclosure of restricted cash and cash equivalents [text block] Revenues Disclosure of revenue [text block] Actuarial assumptions [Abstract] Disclosure of sensitivity analysis for actuarial assumptions [abstract] Actuarial assumptions and sensitivity analysis Disclosure of sensitivity analysis for actuarial 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Total shareholders' equity Balance, beginning of period Balance, end of period Equity Shareholders' equity Total shareholders' equity and liabilities Equity and liabilities SHAREHOLDERS' EQUITY AND LIABILITIES Equity [Member] Fair values of options granted (in CHF per share) Exercise price, share options granted Expense charged against the income statement Expense from share-based payment transactions with employees Finance costs Finance costs paid, classified as operating activities Finance income / (expense), net Finance result, net Finance income (cost) Interest income Finance income received, classified as operating activities Financial assets Financial assets, category [member] Financial liabilities Financial liabilities, category [member] Furniture [Member] Gain (loss) in finance income/(expense), net Foreign currency remeasurement gain/(loss), net Foreign exchange gain (loss) Acquisition Cost [Member] Statements of Income / (Loss) [Abstract] Income tax expense Effective income tax rate benefit / (expense) Tax expense (income), continuing operations Income tax expense Income tax relating to remeasurements of defined benefit plans of other comprehensive income Net increase / (decrease) in cash and cash equivalents Net increase / (decrease) in cash and cash equivalents Increase (decrease) in cash and cash equivalents Increase in tax losses available as an offset Impact on the net defined benefit obligation Increase (decrease) in defined benefit obligation due to reasonably possible decrease in actuarial assumption Impact on the net defined benefit obligation Increase (decrease) in defined benefit obligation due to reasonably possible increase in actuarial assumption Net pension cost Increase (decrease) in net defined benefit liability (asset) Shares issued (in shares) Increase (decrease) in number of ordinary shares issued Exercise of options Increase (decrease) through exercise of options, equity Share-based payments Increase (decrease) through share-based 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[Member] Total liabilities Liabilities Defined benefit obligation, beginning of period Defined benefit obligation, end of period Defined benefit obligation Net defined benefit liability (asset) Liquidity Risk [Member] Liquidity risk [member] Income taxes [Abstract] Income taxes [Abstract] Subsequent Event [Member] Major purchases of assets [member] Maturity [axis] Net defined benefit liability (asset) [axis] Net defined benefit liability (asset) [member] Non-adjusting events after reporting period [axis] Non-adjusting events after reporting period [member] Total non-current assets Non-current assets Non-current assets Non-current assets [abstract] Long-term financing obligation Non-current financial liabilities Accrued interest - long-term Non-current interest payable Total non-current liabilities Non-current liabilities Non-current liabilities Non-current liabilities [abstract] Net employee defined benefit liabilities Total liability Net defined benefit liabilities, beginning of period Net defined benefit liabilities, end of period Non-current provisions for employee benefits Deposits in escrow accounts Financial assets 2018 [Member] Within One Year [Member] Loss Expiry, December 31, 2017 [Member] Number of restricted shares granted (in shares) Granted during the year (in shares) Number of non-vested share awards granted (in shares) Exercised during the year (in shares) Shares vested (in shares) Cancelled during the year (in shares) Forfeited during the year (in shares) Number of other equity instruments forfeited in share-based payment arrangement Non-vested (in shares) Non-vested (in shares) Number of other equity instruments outstanding in share-based payment arrangement Outstanding at beginning of period (in shares) Outstanding at end of period (in shares) Number of share options outstanding in share-based payment arrangement Exercisable (in shares) Number of share options exercisable in share-based payment arrangement Exercised during the year (in shares) Options exercised Number of share options exercised in share-based payment arrangement Cancelled during the year (in shares) Number of share options expired in share-based payment arrangement Forfeited during the year (in shares) Number of share options forfeited in share-based payment arrangement Number of options granted (in shares) Granted during the year (in shares) Number of options awarded (in shares) Issuance of shares: Shares outstanding (in shares) Number of shares outstanding Total operating expenses Operating expense Common Shares [Member] Ordinary shares [member] Other comprehensive loss Other comprehensive income - Re-measurement losses on defined benefit plans (net of tax of CHF 0 for all periods) Re-measurement through other comprehensive income Other comprehensive income, net of tax, gains (losses) on remeasurements of defined benefit plans Other accrued expenses Other current liabilities Other receivables Other current receivables Other finance income/(expense) Nominal value per share (in CHF per share) Par value per share Transaction costs of issue of shares Payments for share issue costs Benefit payments Benefits payments Payments from plan, net defined benefit liability (asset) Percentage decrease in actuarial assumption Percentage of reasonably possible decrease in actuarial assumption Percentage increase in actuarial assumption Percentage of reasonably possible increase in actuarial assumption Fair value of plan assets, end of period Fair value of plan assets, beginning of period Plan assets, at fair value Fair Value of Plan Assets [Member] Plan assets [member] Net pension cost through statement of income Post-employment benefit expense, defined benefit plans Preferred Shares [Member] Preference shares [member] Prepaid expenses and accrued income [Abstract] Defined Benefit Obligation [Member] Present value of defined benefit obligation [member] Proceeds from long-term debt Proceeds from issuance of shares-option plans Proceeds from exercise of options Gross proceeds received Proceeds from issue of ordinary shares Proceeds from issuance of preferred Series E Private placement extension financing Products and services [axis] Products and services [member] Income / (loss) for the period Income / (loss) for the period Net income / (loss) for the period Net income / (loss) attributable to owners of the Company Earnings per share (EPS) [Abstract] Profit (loss), attributable to ordinary equity holders of parent entity [abstract] Income / (loss) before tax Profit (loss) before tax Operating income / (loss) Profit (loss) from operating activities Property, plant and equipment Property, plant and equipment, beginning of period Property, plant and equipment, end of period Property, plant and equipment [member] Commitments Provisions Purchases of property, plant and equipment Purchase of property, plant and equipment, classified as investing activities Range [axis] Ranges [member] Income tax expense reconciled to Income / (loss) [Abstract] Reconciliation of accounting profit multiplied by applicable tax rates [abstract] Property, plant and equipment [Abstract] Reconciliation of changes in property, plant and equipment [abstract] Lease expense Rental expense Research and development expenses Total research and development expenses Research and development expense Accumulated losses Retained earnings Accumulated Losses [Member] Retained earnings [member] Plan assets gains/(losses) Return on plan assets, net defined benefit liability (asset) Total revenue Revenue Revenue Revenues [Abstract] Contract revenue Revenue from contracts with customers Interest income General and administrative expenses Total general and administrative expenses Selling, general and administrative expense Transaction costs Share issue related cost Share premium Share Premium [Member] Share-based payment arrangements [member] Statements of Cash Flows [Abstract] Statements of Changes in Equity [Abstract] Statement of changes in equity [line items] Statement of changes in equity [table] Statements of Comprehensive Income / (Loss) [Abstract] Balance Sheets [Abstract] Effect of unrecognized carry forward tax loss Tax benefit arising from previously unrecognised tax loss, tax credit or temporary difference of prior period used to reduce current tax expense Effect of unused tax losses and tax offsets not recognized as deferred tax assets Tax benefit arising from previously unrecognised tax loss, tax credit or temporary difference of prior period used to reduce deferred tax expense Permanent differences Tax effect of revenues exempt from taxation Tax expense / (benefit) calculated at the statutory rate of 20.5% (21% for 2016 and 22% for 2015) Temporary difference, unused tax losses and unused tax credits [axis] Temporary difference, unused tax losses and unused tax credits [member] Top of Range [Member] Top of range [member] Trade payables and other payables Trade payables and other payables Trade and other current payables Trade payables and accrued liabilities [Abstract] Other current receivables [abstract] Trade and other receivables [abstract] Types of contracts [axis] Types of contracts [member] Types of risks [axis] Risks [member] Types of share-based payment arrangements [axis] Deductible Temporary Differences Related to the Retirement Benefit Plan [Member] Unused tax credits [member] Unused tax losses Unused tax losses for which no deferred tax asset recognised Tax Losses [Member] Unused tax losses [member] Useful lives or depreciation rates, property, plant and equipment Weighted average duration period for defined benefit obligation Weighted average duration of defined benefit obligation Exercised during the year (in CHF per share) Weighted average exercise price of other equity instruments exercised or vested in share-based payment arrangement Cancelled during the year (in CHF per share) Weighted average exercise price of other equity instruments expired in share-based payment arrangement Forfeited during the year (in CHF per share) Weighted average exercise price of other equity instruments forfeited in share-based payment arrangement Granted during the year (in CHF per share) Weighted average exercise price of other equity instruments granted in share-based payment arrangement Non-vested (in CHF per share) Non-vested (in CHF per share) Weighted average exercise price of other equity instruments outstanding in share-based payment arrangement Exercisable (in CHF per share) Weighted average exercise price of share options exercisable in share-based payment arrangement Exercised during the year (in CHF per share) Cancelled during the year (in CHF per share) Forfeited during the year (in CHF per share) Granted during the year (in CHF per share) Weighted average share price of common share options exercised (in CHF per share) Weighted average share price for share options in share-based payment arrangement exercised during period at date of exercise Exercise price for outstanding options (in CHF per share) Outstanding at beginning of period (in CHF per share) Outstanding at end of period (in CHF per share) Weighted average exercise price of share options outstanding in share-based payment arrangement Fair value of options granted Grant date fair value of the replacement award Weighted average fair value at measurement date, share options granted Weighted average remaining term (years) Weighted average remaining contractual life of outstanding share options Weighted average share price of options granted (in CHF per share) Weighted average share price Weighted average fair value, options granted (in CHF per share) Weighted average share price, share options granted Weighted-average number of shares used to compute EPS basic (in shares) Weighted average number of ordinary shares outstanding Amendment Flag Current Fiscal Year End Date Document Period End Date Entity [Domain] Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Current Reporting Status Entity Filer Category Entity Public Float Entity Registrant Name Entity Central Index Key Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Period Focus Legal Entity [Axis] Document Type CHF [Member] Switzerland, Francs EUR [Member] Euro Member Countries, Euro USD [Member] United States of America, Dollars All Currencies [Domain] Currency [Axis] Financial Result, net [Abstract] Financial Result, net [Abstract] A class of employee benefits expense that represents wages and salaries that are allocated to general and administrative expense. [Refer: Employee benefits expense] General and administrative expense allocation, wages and salaries Payroll expenses The amount of expense from share-based payment transactions with employees allocated to general and administrative expense. General and administrative expense allocation, expense from share-based payment transactions with employees Share-based compensation The amount of expense from share-based payment transactions with employees that are allocated to research and development expenses. Research and development expense allocation, expense from share-based payment transactions with employees Share-based compensation The amount of all operating expenses allocated to general and administrative expenses. General and administrative expense allocation, operating expense Operating expenses General and Administration [Abstract] General and Administration [Abstract] The amount of all operating expenses allocated to research and development expenses. Research and development expense allocation, operating expense Operating expenses A class of employee benefits expense that represents wages and salaries that are allocated to research and development expenses. [Refer: Employee benefits expense] Research and development expense allocation, wages and salaries Payroll expenses Research and Development Expenses [Abstract] Research and Development [Abstract] Expenses by category [Abstract] The disclosure of detailed information about revenue. Disclosure of detailed information about revenue [Table Text Block] Revenues The amount of consideration recognized for the milestone payment(s) associated with a collaborative agreement during the period. Collaborative Agreement, Milestone Payment Recognized Milestone payment recognized The 2014 contractual research agreement associated with collaboration with Piramal Imaging. License and collaboration agreement of 2014, Piramal Imaging [Member] License and Collaboration Agreement of 2014, Piramal Imaging [Member] The 2006 contractual research agreement associated with collaboration with Genentech. Collaboration agreement of 2006, Genentech [Member] Collaboration Agreement of 2006, Genentech [Member] The 2012 contractual research agreement associated with collaboration with Genentech. Collaboration agreement of 2012, Genentech [Member] Collaboration Agreement of 2012, Genentech [Member] The contractual research agreement associated with collaboration with Essex Bio-Technology Limited. Collaboration With Essex Bio-Technology Limited [Member] Contractual arrangement that involves two or more parties that both: (i) actively participate in a joint operating activity and (ii) are exposed to significant risks and rewards that depend on the commercial success of the joint operating activity. Collaboration and License Revenue Agreements [Member] Collaboration and License Revenue [Member] Funding provided for certain types of expenditures in connection with research and development activities over a contractually-defined period from the Michael J. Fox Foundation. Grants, Michael J. Fox Foundation [Member] Grant from Michael J. Fox Foundation [Member] Revenue earned from non-repayable sum of money awarded to an entity to carry out a specific purpose as provided in grant agreements. Grant revenue [Member] Grant revenue [Member] The period over which collaborating entities are contracted to perform research, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Collaborative agreement, Joint research collaboration period Period of joint research collaboration The cumulative payments recognized related to revenue from upfront license fees, technology fees, milestone payments and revenue from research agreements and associated with a collaborative agreement. Collaborative Agreement, Cumulative Payments Recognized Cumulative payments recognized The amount that the entity is eligible to receive for clinical milestones from a collaborative agreement.. Collaborative agreement, Collaboration contract receivable for clinical milestones Collaboration contract receivable for clinical milestones Period of time that notice is required to be given for cancellation of the collaborative agreement contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Collaborative agreement, Notice of contract termination period Period to provide notice of termination of agreement The research and development of medicines for the treatment of Alzheimer's disease. Anti-Abeta antibody in AD [Member] Anti-Abeta Antibody in AD [Member] The period over which deferred revenue is recognized in income, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Revenue recognition deferral period Revenue recognition deferral period The term of a grant agreement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Term of grant Term of grant The amount that the entity is eligible to receive for regulatory, commercialization and sales milestones from a collaborative agreement. Collaborative agreement, Collaboration contract receivable for regulatory, commercialization and sales milestones Collaboration contract receivable for regulatory, commercialization and sales milestones Period for initial research plan under a collaborative agreement. Period for Initial Research Plan Period for initial research plan The number of companies involved in joint research collaboration. Collaborative agreement, Number of companies entered into joint research collaboration Number of companies entered into joint research collaboration Payment(s) received for milestone payments associated with a collaborative agreement. Collaborative agreement, Milestone payment received Milestone payment received The subsequently amended period over which collaborating entities are contracted to perform research, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Collaborative Agreement, Joint Research Collaboration, Subsequently Amended Period Joint research collaboration, subsequently amended period The number of indications built on the same research program associated with a collaborative agreement. Collaborative agreement, Number of indications Number of additional indications The amount that the entity is eligible to receive from a collaborative agreement. Collaborative agreement, Receivable expected Collaboration contract receivable The cumulative payments received related to revenue from upfront license fees, milestone payments and revenue from research agreements associated with a collaborative agreement. Collaborative agreement, Cumulative payments received Cumulative payments received Amortized period over which revenue is recognized in income, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Revenue Recognition Amortization Period Revenue recognition amortization period The research and development of medicines for the treatment of Alzheimer's disease. Anti-tau antibody in AD [Member] Anti-tau Antibody in AD [Member] The research and development of medicines for the treatment of recombinant protein therapeutic candidate. Recombinant Protein Therapeutic Candidate [Member] Recombinant Protein Therapeutic Candidate [Member] The research and development of a vaccine for the treatment of Alzheimer's disease. Tau Vaccine in AD [Member] Tau Vaccine in AD [Member] The research and development of medicines for the treatment of Alzheimer's disease through molecular imaging. Tau-PET imaging agent in AD [Member] Tau-PET Imaging Agent in AD [Member] The research and development of medicines for the treatment of Alzheimer's disease. Alpha-synuclein and TDP-43 PET tracer in AD [Member] Alpha-synuclein and TDP-43 PET Tracer in AD [Member] Revenue from public institutions and foundations for a contractually-defined purpose and period. Grant revenue Grant revenue recognized The disclosure of detailed information about other current receivables. Disclosure of detailed information about other current receivables [Table Text Block] Other current receivables Refers to the maturity period over which the entity considers carrying value of current receivables to correspond to their fair value. Period of maturity, receivables fair value carrying amount Maturity period of assets Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. Disclosure of other current receivables [Line Items] Schedule disclosing information related to other current receivables. Disclosure of other current receivables [Table] The disclosure of other current receivables. Disclosure of other current receivables [Text Block] Other current receivables Other current receivables [Abstract] The disclosure of detailed information about trade payables and accrued liabilities. Disclosure of detailed information about trade payables and accrued liabilities [Table Text Block] Trade payables and accrued liabilities Number of equity-based instrument plans approved by the entity. Number of Equity-based Instrument Plans Number of equity-based instrument plans A share-based payment arrangement that existed at any time during the reporting period. Stock option plan C1 [Member] Stock Option Plan C1 [Member] A share-based payment arrangement that existed at any time during the reporting period. Stock option plan B [Member] Stock Option Plan B [Member] The 2016 Plan authorizes the grant of incentive and non-qualified share options, share appreciation rights, restricted share awards, restricted share units, unrestricted share awards, performance share awards, performance-based awards to covered employees and dividend equivalent rights. 2016 Share Option and Incentive Plan [Member] A share-based payment arrangement that existed at any time during the reporting period. Stock option plan A [Member] Stock Option Plan A [Member] Refers to personnel employed by the entity. Employees [Member] Share-based plans outstanding [Abstract] Share-based plans outstanding [Abstract] The number of new shares issued upon the conversion of stock. Shares issued, conversion of stock Additional shares issued upon conversion (in shares) This member stands for equity instruments that are subordinate to all other classes of equity instruments and that are senior in some aspects to ordinary shares, but subordinate to debt instruments in terms of claim. Ordinary and Preference Shares [Member] Common and Preferred Shares [Member] For vesting requirements for a type of share-based payment arrangement that existed at any time during the period, this element represents the period which an employees right to exercise and award in no longer contingent on satisfaction of a service condition. Vesting requirements for share-based payment arrangement, award vesting period Vesting conditions Vesting conditions The maximum term of other equity instruments (ie other than share options) granted for a type of share-based payment arrangement that existed at any time during the period. Maximum Term Of Other Equity Instruments Granted For Share Based Payment Arrangement Contractual life of non-vested share awards The number of other equity instruments (ie other than share options) vested in a share-based payment arrangement. Number of other equity instruments vested in share-based payment arrangement Vested (in shares) Number Of Non-vested Shares [Abstract] Number of non-vested shares [Abstract] The weighted average exercise price of other equity instruments (ie other than share options) vested in a share-based payment arrangement. [Refer: Weighted average [member]] Weighted average exercise price of other equity instruments vested in share-based payment arrangement Vested (in CHF per share) This member stands for equity instruments that are prohibited for sale for a specified period of time. Restricted shares [Member] Restricted Share Awards [Member] This member stands for share instrument which is convertible to stock or an equivalent amount of cash, after a specified period of time or when specified performance conditions are met. Restricted Shares and Restricted Share Units [Member] Non-vested Share Awards [Member] The cash inflow from payments from collaboration agreements where entity recognizes revenue from upfront fees under the collaboration agreements pro-rata over the term of the estimated period of performance under each agreement. Revenue, upfront fees received Upfront fees Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. Deferred income [Line Items] Schedule disclosing information related to details of deferred income. Deferred income [Table] The amount of current accrued research and development costs. Current accrued research and development costs Accrued research and development costs Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. Cash and cash equivalent [Line Items] Schedule of cash and cash equivalent balances, including foreign currencies in which the balances are denominated. Cash and cash equivalents [Table] Weighted Average Exercise Price [Abstract] Weighted Average Exercise Price [Abstract] Weighted Average grant date fair value [Abstract] The weighted average remaining contractual life of exercisable share options. Weighted average remaining contractual life of exercisable share options Exercisable Weighted Average Remaining [Abstract] Weighted Average Remaining Term (Years) [Abstract] Number of Options [Abstract] Number of Options [Abstract] The disclosure of detailed information about cash and cash equivalents. Disclosure of detailed information about cash and cash equivalents [Table Text Block] Cash and cash equivalents An former executive officer responsible for overseeing the financial activities of the entity. Former Chief Executive Financial Officer [Member] Former Chief Financial Officer [Member] The maximum term of options granted for a type of share-based payment arrangement that existed at any time during the period. Maximum term of options granted for share-based payment arrangement Expiry period of options Contractual life of options Share-based payment arrangement [Abstract] Share-based compensation [Abstract] Tax losses split by expiry date [Abstract] Tax losses split by expiry date [Abstract] This member stands for a time band of later than seven years and not later than eight years. Later Than Six Years And Not Later Than Eight Years [Member] Loss Expiry, December 31, 2024 [Member] This member stands for a time band of later than five years and not later than six years. Later than five years and not later than six years [Member] Loss Expiry, December 31, 2022 [Member] This member stands for a time band of later than six years and not later than seven years. Later than six years and not later than seven years [Member] Loss Expiry, December 31, 2023 [Member] The disclosure of detailed information about income tax reconciliation. Disclosure of detailed information about income tax reconciliation [Table Text Block] Income tax expense reconciled to Income / (loss) The disclosure of detailed information about the expiration of income tax losses. Disclosure of detailed information about income tax losses expiry [Table Text Block] Tax losses expiry dates This member stands for equity instruments that are convertible to stock after a specified period of time. Restricted Stock Units [Member] Restricted Stock Units [Member] Key managers of an entity who collectively have responsibility of governing the entity. Board of Directors [Member] Board of Directors [Member] Directors [Member] Key managers of an entity who collectively have responsibility of governing the entity and Key managers, or ranking officers of an entity, appointed to their position by the board of directors. Board of Directors and Executive Management [Member] Board of Directors and Executive Management [Member] Key managers, or ranking officers of an entity, appointed to their position by the board of directors. Executive Management [Member] Executive Management [Member] Executives [Member] An former executive officer responsible for overseeing the financial activities of the entity. Former Chief Financial Officer [Member] The number of persons that comprise key management of the entity that are the included in Board of Directors excluding the Chief Executive Officer. Number of persons, key management, Board of Directors Number of individuals, Board of Directors The number of persons that comprise key management of the entity that are Executive Management. Number of persons, key management, Executive Management Number of individuals, Executive Management The tax benefit recognized from a reduction in income taxes granted by the taxing jurisdiction. Tax benefit, income tax holiday Effect of Swiss Tax Holidays The effective income tax rate. Effective tax rate The value of underwriting fees in a noncash transaction related to share issue costs. Underwriting fees, in noncash financing activities Underwriting fees The number of unique proprietary platform technologies to discover, design and develop medicines and diagnostics to target misfolded proteins. Number of technology platforms Number of proprietary technology platforms The entire disclosure for general information about the entity. Disclosure of general information about the entity explanatory [Text Block] General information General information [Abstract] This member represents the equity instruments from the right of the underwriter to sell additional equity shares over the initial allotment. Option for Over-Allotment [Member] Over-Allotment Option [Member] Price per share received for common stock issued or sold an initial public offering. Share Price, initial public offering, IPO share price (in dollars per share) The increase (decrease) to the balance of share premium which is the amount received or receivable from the issuance of the entity's shares in excess of nominal value. Increase (decrease) to share premium through issuance of equity Increase in share premium Initial Public Offering [Abstract] Initial Public Offering (IPO) [Abstract] This member represents receivables classified as other. Other receivables [Member] Other Current Receivables [Member] This member represents cash on hand and demand deposits, along with short-term, highly liquid investments that are readily convertible to known amounts of cash and that are subject to an insignificant risk of changes in value. Cash on hand and cash equivalents [Member] Cash and Cash Equivalents [Member] This member stands for trade and other payables. Trade and Other Payables [Member] This member stands for long-term financial liabilities. Long-term Financial Liabilities [Member] Long-Term Financing Obligation [Member] This member stands for accrued expenses. Accrued Expenses [Member] The increase in net loss arising from a decrease in the foreign exchange rate. Increase in net loss, foreign exchange rate decrease Net loss for period increase, result of foreign exchange rate decrease The periodic interval in which the entity performs a rolling forecast of the entity's cash position. Liquidity management, rolling forecast period Cash position rolling forecast period The decrease in net loss arising from a increase in the foreign exchange rate. Decrease in net loss, foreign exchange rate increase Net loss for period decrease, result of foreign exchange rate increase The number of banks holding the entity's deposits of cash and cash equivalents. Number of banks holding deposits, cash and cash equivalents Number of banks holding cash and cash equivalents The percentage decrease to spot exchange rate at the end of the reporting period. Closing foreign exchange rate, decrease Percentage exchange rate weakened The percentage increase to spot exchange rate at the end of the reporting period. Closing foreign exchange rate, increase Percentage exchange rate strengthened Financial risks [Abstract] Financial risks [Abstract] Financial assets and liabilities [Abstract] Financial assets and liabilities [Abstract] The percentage of outstanding common shares of the entity held by preferred stock owners. Percentage of shares outstanding held by preference stock owners Percentage of shares outstanding owned by Preferred shareholders The number of classes of the entity's preferred stock outstanding. Number of classes of preferred stock outstanding Number of preferred shares classes outstanding The nominal value of subscription shares. Share subscription amount Aggregate subscription amount Subscription amount The term over which preferred shares have been the primary source of equity financing. Term of equity financing, preferred stock Term of equity financing The increase (decrease) in the number of preferred shares issued. Increase (decrease) in number of preferred shares issued Private placement shares issued (in shares) The number of equity transactions with owners of the entity to increase the capital of the entity. Number of capital increases Number of separate capital increases Price per share received for common stock issued or sold in a private placement transaction. Share Price, Private Placement, Sale of Stock Private placement share price (in dollars per share) Private placement share price (in dollars/CHF per share) The ratio applied to the conversion of a stock split. For example, one share converted to two shares or one share converted to four shares. Stock split conversion ratio Stock split ratio The ratio applied to the conversion of one class of stock convertible to another class of stock. For example one preferred share can be converted to one common share or one preferred share can be converted to two common shares. Convertible shares, conversion ratio Conversion ratio of preferred shares to common shares The number of voting rights entitled to a share holder for each share owned. For example, one vote for one share owned, or two votes for one share owned. Voting rights, number of votes per share held Number of votes entitled for each preferred share Preferred Shares [Abstract] Preferred Shares [Abstract] The cash inflow from milestone payments from collaborative arrangements with third parities. Collaborative arrangements, milestone payment received Receipt of clinical milestone payment Going Concern [Abstract] Going concern [Abstract] A pharmaceutical company. Janssen Pharmaceuticals [Member] Janssen [Member] A biotechnology company that develops medicines. Genentech [Member] Genentech [Member] Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. Disclosure of classes of going concern [Line Items] Schedule disclosing information related to the entity's ability to continue as a going concern. Disclosure of going concern [Table] This member represents the equity instruments that are the first or initial sale of equity shares by a private company to the public. Initial Public Offering [Member] Initial Public Offering [Member] This member stands for series E equity instruments that are senior in some aspects to ordinary shares, but subordinate to debt instruments in terms of claim. [Refer: Ordinary shares [member]] Preference shares, Series E [Member] Series E [Member] Preferred Shares Series E [Member] Basis of preparation [Abstract] The disclosure of detailed information about carrying amounts of financial assets and financial liabilities. Disclosure of detailed information about carrying amounts of financial assets and financial liabilities [Table Text Block] Carrying amounts of financial assets and financial liabilities This member stands for a class of property, plant and equipment representing improvements to assets held under a lease agreement and fixtures and fittings that are not permanently attached to real property. Leasehold improvements and fixtures and fittings [Member] Leasehold Improvements / Furniture [Member] Residual value over its estimated useful life [Abstract] Residual value over its estimated useful life [Abstract] The disclosure of detailed information about the useful life of property, plant and equipment. Schedule of information about property, plant and equipment useful life [Table Text Block] Estimated useful life The amount of provision for contractual obligations requiring payment of royalties to a third party. Provision, royalty obligation Royalty payment obligation The amount of provisions for research contracts with external providers. Provisions, research contracts External research projects The period of time required by the lessee in a lease agreement to provide notice of cancellation of a lease to the lessor. Rental contract, period for notice of cancellation Notice period for cancellation of rental contract Commitments [Abstract] Commitments and contingencies [Abstract] Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. Disclosure of information about commitments and contingencies [Line Items] Schedule of disclosing information related to commitments and contingencies. Disclosure of information about commitments and contingencies [Table] The number of equity awards outstanding during the period multiplied by a time-weighting factor. Weighted average number of equity awards outstanding, Weighted average number of equity awards outstanding (in shares) Commitments and contingencies [Abstract] The description of the entity's accounting policy for financial assets and liabilities. Financial assets and liabilities [Policy Text Block] Financial assets and liabilities The description of the entity's accounting policy for the basis for how the entity classifies assets and liabilities as current and non-current. Description of accounting policy for classification of assets and liabilities [Policy Text Block] Current vs. non-current classification The description of the entity's accounting policy for changes to accounting policies not yet adopted by the entity. Disclosure of accounting policy for changes in accounting policies not yet adopted [Policy Text Block] Accounting pronouncements - not yet adopted The description of the entity's accounting policy for judgments that management has made in the process of applying the entity's accounting policies that have the most significant effect on amounts recognized in the financial statements along with information about the assumptions that the entity makes about the future, and other major sources of estimation uncertainty at the end of the reporting period, that have a significant risk of resulting in a material adjustment to the carrying amounts of assets and liabilities within the next year. Description of accounting policy for accounting judgments and estimates [Policy Text Block] Critical judgments and accounting estimates The period or time limit over which financial losses of the entity for preceding years can be deducted from the taxable revenue for a period. Income tax loss, Carryforward period Tax loss carryforward period Number of operating segments reported by the entity. Operating segments, number Number of operating segments Number of reportable segments reported by the entity. Reportable segments, number Number of reportable segments The amount agreed to purchase previous tenant's lab equipment under lease contract. Purchase of lab equipment Purchase of lab equipment The additional lease area to expand premises under lease contract. Additional lease space Additional lease space Changes in fair value of plan assets [Abstract] Changes in fair value of plan assets [Abstract] The 2014 contractual research agreement associated with collaboration with Janssen Pharmaceuticals. Collaboration agreement of 2014, Janssen Pharmaceuticals [Member] Janssen [Member] Collaboration Agreement of 2014, Janssen Pharmaceuticals [Member] The 2016 contractual research agreement associated with collaboration with Biogen. Collaboration agreement of 2016, Biogen [Member] Biogen [Member] Collaboration Agreement of 2016, Biogen [Member] Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. Prepaid Expenses and Accrued Income [Line Items] Schedule disclosing information related to details of Prepaid expenses and accrued income. Prepaid Expenses and Accrued Income [Table] The disclosure of detailed information about prepaid expenses and accrued income. Disclosure of detailed information about prepaid expenses and accrued income [Table Text Block] Prepaid expenses and accrued income The disclosure of prepayments and accrued income. Disclosure of prepaid expenses and accrued income [Text Block] Prepaid expenses and accrued income This member stands for a class of property, plant and equipment representing laboratory equipment. Laboratory equipment [Member] Lab Equipment [Member] Laboratory Equipment [Member] The number of escrow accounts with cash deposits of the entity. Number of escrow deposit accounts Number of deposits in escrow accounts Change in net defined benefit liability [Abstract] Change in net defined benefit liability [Abstract] The reasonably possible percentage of the decrease in the actuarial assumption used to determine the present value of defined benefit obligation. Percentage of reasonably possible decrease in actuarial assumption [Member] -0.5% Decrease [Member] The reasonably possible percentage of the increase in the actuarial assumption used to determine the present value of defined benefit obligation. Percentage of reasonably possible increase in actuarial assumption [Member] +0.5% Increase [Member] Sensitivity analysis, actuarial assumptions [Abstract] Sensitivity analysis [Abstract] Published actuarial tables that detail assumptions about mortality and disability rates which are used to determine benefit obligations for defined benefit plans. Issued Actuarial Tables, Switzerland Mortality and disability rates The increase in the net defined benefit liability (asset) resulting from the passage of time. Interest income, net defined benefit liability (asset) Interest income Interest income The contributions paid to the plan are computed as a percentage of salary, adjusted for the age of the employee. Defined benefit plan, percentage of contribution Contributions paid to the plan by computing percentage in salary Net pension cost in statement of income [Abstract] Net pension cost in statement of income [Abstract] Defined benefit pension plan amount recognized in balance sheet [Abstract] Defined benefit pension plan amount recognized in balance sheet [Abstract] This member stands for the employee portion of a domestic defined benefit plan. Defined benefits plan, Employer [Member] Employer [Member] This member stands for the employee portion of a domestic defined benefit plan. Defined benefits plan, Employee [Member] Employee [Member] The decrease in the net defined benefit liability (asset) resulting from interest costs resulting from the passage of time. Interest cost, net defined benefit liability (asset) Interest cost Interest cost The decrease (increase) in a net defined benefit liability (asset) resulting from actuarial gains (losses) arising from changes in other assumptions that result in remeasurements of the net defined benefit liability (asset). Actuarial gains (losses) arising from changes in other assumptions, net defined benefit liability (asset) Other actuarial gains / (losses) The decrease (increase) in a net defined benefit liability (asset) resulting from actuarial gains (losses) arising from changes in the substantive terms of an existing defined benefit plan or the initiation of a new plan. Actuarial losses (gains) arising from changes in benefit plan, net defined benefit liability (asset) Plan amendment Impact of plan amendment The amount of contractual commitments for funding research grants. Funding commitment The percentage of funding commitment amount required to be reimbursed as per a research grant agreement of which the amount includes the entire funding commitment plus an additional upcharge. Reimbursement percentage of funding commitment. Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. Long term financing obligation [Line Items] Funding provided for certain types of expenditures in connection with research and development activities over a contractually-defined period from the LuMind Research Down Syndrome Foundation. Grants, LuMind Research Down Syndrome Foundation [Member] Schedule disclosing information related to details of long term financing obligations. Long term financing obligation [Table] The disclosure of long term financing obligations. Disclosure of Long term financing obligation [Text Block] Disclosure of Long term financing obligation Long term financing obligation [Abstract] Post balance sheet events [Abstract] The cash outflow for deposit of rent. Cash Advances for Rent Deposit Rent deposit Adjustments for increase (decrease) in long-term financial liabilities to reconcile profit (loss) to net cash flow from (used in) operating activities. Adjustments for Increase (Decrease) Long-term Financial Liabilities Long-term financing obligation Adjustments for increase (decrease) in interest payable, to reconcile profit (loss) to net cash flow from (used in) operating activities. Adjustments for Accrued Interest Payable Accrued interest on long-term debt The cash inflow from repayments to settle amounts loaned, classified as financing activities. Proceeds from loan repayments Proceeds from employee loan repayments Adjustments for increase (decrease) in accrued expenses to reconcile profit (loss) to net cash flow from (used in) operating activities. Adjustments for increase (decrease) in accrued expenses Accrued expenses Adjustments for decrease (increase) in accrued income to reconcile profit (loss) to net cash flow from (used in) operating activities. [Refer: Profit (loss)] Adjustments for decrease (increase) in accrued income Accrued income Adjustments for decrease (increase) in prepaid expenses to reconcile profit (loss) to net cash flow from (used in) operating activities. Adjustments for decrease (increase) in prepaid expense Prepaid expenses Changes in working capital [Abstract] Changes in working capital: The increase in equity through the issue of series E extension preference equity instruments that are senior in some aspects to ordinary shares, but subordinate to debt instruments in terms of claim. Issue of equity, extension preference shares, series E Preferred Series E extension shares The increase in equity through the issue of series E preference equity instruments that are senior in some aspects to ordinary shares, but subordinate to debt instruments in terms of claim. Issue of equity, preference shares, series E Issuance of preferred Series E shares The increase in equity through the issue of restricted share awards. Issue of Equity, Restricted Share Awards Restricted Share Awards The cash inflow from issuing ordinary shares net of underwriting fees. Proceeds from issuing shares, net of underwriting fees Proceeds from IPO net of underwriting fees Proceeds from issuance of common shares Expenses, Operating [Abstract] Operating expenses The amount of current other receivables and receivables from value added taxes and withholding taxes. Current receivables classified as other and value added and withholding taxes Other current receivables Total The amount of current accrued income and grant receivables. Current accrued income and grant receivables Accrued income Document and Entity Information [Abstract]