Clementia Pharmaceuticals Inc. (SEC Filing Page | XBRL Cloud Viewer | XBRL Instance)

Line Label Object Class Period Type Balance Report ElementName
1 000 - Document - Document And Entity Information Network

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2 Document Information [Table] Table

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3 Legal Entity [Axis] Axis dei:LegalEntityAxis
4 Entity [Domain] Member dei:EntityDomain
5 Document Information [Line Items] LineItems dei:DocumentInformationLineItems
6 Entity Registrant Name Concept (Text/String) For Period dei:EntityRegistrantName
7 Entity Central Index Key Concept (CIK Number) For Period dei:EntityCentralIndexKey
8 Trading Symbol Concept (Text/String) For Period dei:TradingSymbol
9 Current Fiscal Year End Date Concept (Month/Day) For Period dei:CurrentFiscalYearEndDate
10 Entity Filer Category Concept (Filer Category) For Period dei:EntityFilerCategory
11 Entity Current Reporting Status Concept (Yes/No) For Period dei:EntityCurrentReportingStatus
12 Entity Voluntary Filers Concept (Yes/No) For Period dei:EntityVoluntaryFilers
13 Entity Well-known Seasoned Issuer Concept (Yes/No) For Period dei:EntityWellKnownSeasonedIssuer
14 Entity Emerging Growth Company Concept (Yes/No) For Period dei:EntityEmergingGrowthCompany
15 Entity Ex Transition Period Concept (Yes/No) For Period dei:EntityExTransitionPeriod
16 Entity Small Business Concept (Yes/No) For Period dei:EntitySmallBusiness
17 Entity Common Stock, Shares Outstanding (in shares) Concept (Shares) As Of dei:EntityCommonStockSharesOutstanding
18 Document Type Concept (Submission Type) For Period dei:DocumentType
19 Document Period End Date Concept (Date) For Period dei:DocumentPeriodEndDate
20 Document Fiscal Year Focus Concept (Year) For Period dei:DocumentFiscalYearFocus
21 Document Fiscal Period Focus Concept (Fiscal Period) For Period dei:DocumentFiscalPeriodFocus
22 Amendment Flag Concept (Yes/No) For Period dei:AmendmentFlag
23 Entity Shell Company Concept (Yes/No) For Period dei:EntityShellCompany
24 001 - Statement - Consolidated Statements of Financial Position Network

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25 Statement Table [Table] Table

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26 Legal Entity [Axis] Axis dei:LegalEntityAxis
27 Entity [Domain] Member dei:EntityDomain
28 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
29 Current assets Abstract ifrs-full:CurrentAssetsAbstract
30 Cash Concept (Monetary) As Of Debit ifrs-full:CashAndCashEquivalents
31 Short-term investments Concept (Monetary) As Of Debit ifrs-full:ShorttermDepositsNotClassifiedAsCashEquivalents
32 Interest receivable Concept (Monetary) As Of Debit ifrs-full:CurrentInterestReceivable
33 Sales tax and other receivables Concept (Monetary) As Of Debit cmta:CurrentSalesTaxAndOtherReceivables
34 Income tax and tax credits receivable Concept (Monetary) As Of Debit cmta:CurrentIncomeTaxAndInvestmentTaxCreditsReceivable
35 Prepaid expenses Concept (Monetary) As Of Debit ifrs-full:CurrentPrepaidExpenses
36 Total current assets Concept (Monetary) As Of Debit ifrs-full:CurrentAssets
37 Non-current assets Abstract ifrs-full:NoncurrentAssetsAbstract
38 Long-term investments Concept (Monetary) As Of Debit ifrs-full:LongtermDeposits
39 Long-term prepaid expenses Concept (Monetary) As Of Debit cmta:NoncurrentPrepaidExpenses
40 Property and equipment Concept (Monetary) As Of Debit ifrs-full:PropertyPlantAndEquipment
41 Intangible assets Concept (Monetary) As Of Debit ifrs-full:IntangibleAssetsOtherThanGoodwill
42 Total non-current assets Concept (Monetary) As Of Debit ifrs-full:NoncurrentAssets
43 Total assets Concept (Monetary) As Of Debit ifrs-full:Assets
44 Current liabilities Abstract ifrs-full:CurrentLiabilitiesAbstract
45 Accounts payable and accrued liabilities Concept (Monetary) As Of Credit cmta:CurrentAccountsPayableAndAccruedLiabilities
46 Total liabilities Concept (Monetary) As Of Credit ifrs-full:CurrentLiabilities
47 Equity Abstract ifrs-full:EquityAbstract
48 Common shares Concept (Monetary) As Of Credit ifrs-full:IssuedCapital
49 Contributed surplus Concept (Monetary) As Of Credit ifrs-full:SharePremium
50 Deficit Concept (Monetary) As Of Credit ifrs-full:RetainedEarnings
51 Total equity Concept (Monetary) As Of Credit ifrs-full:Equity
52 Total equity and liabilities Concept (Monetary) As Of Credit ifrs-full:EquityAndLiabilities
53 002 - Statement - Consolidated Statements of Changes in Equity Network

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54 Statement Table [Table] Table

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55 Components of equity [axis] Axis ifrs-full:ComponentsOfEquityAxis
56 Equity [member] Member ifrs-full:EquityMember
57 Issued capital [member] Member ifrs-full:IssuedCapitalMember
58 Share premium [member] Member ifrs-full:SharePremiumMember
59 Retained earnings [member] Member ifrs-full:RetainedEarningsMember
60 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
61 Balance (in shares) Concept (Shares) As Of ifrs-full:NumberOfSharesOutstanding
62 Balance Concept (Monetary) As Of Credit ifrs-full:Equity
63 Share-based compensation (note 9) Concept (Monetary) For Period Credit ifrs-full:IncreaseDecreaseThroughSharebasedPaymentTransactions
64 Net loss and comprehensive loss Concept (Monetary) For Period Credit ifrs-full:ComprehensiveIncome
65 Issuance of common shares upon public offering (in shares) Concept (Shares) For Period cmta:IssuanceOfCommonStock
66 Issuance of common shares upon public offering Concept (Monetary) For Period Credit ifrs-full:IssueOfEquity
67 Share issuance costs Concept (Monetary) For Period Debit ifrs-full:ShareIssueRelatedCost
68 Conversion of preferred shares (note 7) (in shares) Concept (Shares) For Period cmta:ConversionOfConvertiblePreferredShares
69 Conversion of preferred shares (note 7) Concept (Monetary) For Period Credit ifrs-full:IncreaseDecreaseThroughConversionOfConvertibleInstruments
70 Excess of carrying value of preferred shares and embedded derivatives liabilities, over the stated capital of the preferred shares (note 7) Concept (Monetary) For Period Credit cmta:IncreaseDecreaseThroughExcessOfCarryingValueOfPreferredSharesAndEmbeddedDerivativesLiabilitiesOverTheStatedCapitalOfThePreferredShares
71 Deficit reduction (note 7) Concept (Monetary) For Period Credit cmta:ReductionOfDeficit
72 Exercise of stock options (in shares) Concept (Shares) For Period cmta:ExerciseOfStockOptions
73 Exercise of stock options Concept (Monetary) For Period Credit ifrs-full:IncreaseDecreaseThroughExerciseOfOptions
74 Balance (in shares) Concept (Shares) As Of ifrs-full:NumberOfSharesOutstanding
75 Balance Concept (Monetary) As Of Credit ifrs-full:Equity
76 003 - Statement - Consolidated Statements of Net Loss and Comprehensive Loss Network

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77 Statement Table [Table] Table

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78 Legal Entity [Axis] Axis dei:LegalEntityAxis
79 Entity [Domain] Member dei:EntityDomain
80 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
81 Expenses Abstract cmta:ExpensesAbstract
82 Research and development expenses Concept (Monetary) For Period Debit ifrs-full:ResearchAndDevelopmentExpense
83 Tax credits Concept (Monetary) For Period Credit cmta:InvestmentTaxCredits
84 Concept (Monetary) For Period Debit cmta:ResearchAndDevelopmentExpenseNet
85 General and administrative expenses Concept (Monetary) For Period Debit ifrs-full:GeneralAndAdministrativeExpense
86 Interest income Concept (Monetary) For Period Credit ifrs-full:InvestmentIncome
87 Financial expenses Concept (Monetary) For Period Credit ifrs-full:FinanceIncomeCost
88 Net loss before income taxes Concept (Monetary) For Period Credit ifrs-full:ProfitLossBeforeTax
89 Income tax expense Concept (Monetary) For Period Debit ifrs-full:IncomeTaxExpenseContinuingOperations
90 Net loss and comprehensive loss Concept (Monetary) For Period Credit ifrs-full:ComprehensiveIncome
91 Basic and diluted loss per share (in dollars per share) Concept (Share) For Period ifrs-full:BasicAndDilutedEarningsLossPerShare
92 Weighted average number of outstanding basic and diluted shares (in shares) Concept (Shares) For Period ifrs-full:AdjustedWeightedAverageShares
93 004 - Statement - Consolidated Statements of Cash Flows Network

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94 Statement Table [Table] Table

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95 Classes of share capital [axis] Axis ifrs-full:ClassesOfShareCapitalAxis
96 Share capital [member] Member ifrs-full:ClassesOfShareCapitalMember
97 Ordinary shares [member] Member ifrs-full:OrdinarySharesMember
98 Series C preferred shares [member] Member cmta:SeriesCPreferredSharesMember
99 Legal Entity [Axis] Axis dei:LegalEntityAxis
100 Entity [Domain] Member dei:EntityDomain
101 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
102 Operating activities Abstract ifrs-full:CashFlowsFromUsedInOperatingActivitiesAbstract
103 Net loss Concept (Monetary) For Period Credit ifrs-full:ProfitLoss
104 Adjusting items Abstract ifrs-full:AdjustmentsForReconcileProfitLossAbstract
105 Interest income recognized in net loss Concept (Monetary) For Period Credit ifrs-full:AdjustmentsForInterestIncome
106 Depreciation of property and equipment Concept (Monetary) For Period Debit ifrs-full:AdjustmentsForDepreciationExpense
107 Amortization of intangible assets Concept (Monetary) For Period Debit ifrs-full:AdjustmentsForAmortisationExpense
108 Loss on write-off of property and equipment Concept (Monetary) For Period Credit ifrs-full:AdjustmentsForGainLossOnDisposalsPropertyPlantAndEquipment
109 Transaction costs recognized in net loss Concept (Monetary) For Period Debit ifrs-full:AdjustmentsForFinanceCosts
110 Embedded derivative loss recognized in net loss Concept (Monetary) For Period Credit ifrs-full:AdjustmentsForGainsLossesOnChangeInFairValueOfDerivatives
111 Accretion of preferred shares Concept (Monetary) For Period Debit cmta:AdjustmentForAccretionOfPreferredShares
112 Share-based compensation Concept (Monetary) For Period Debit ifrs-full:AdjustmentsForSharebasedPayments
113 Net foreign exchange loss (gain) Concept (Monetary) For Period Debit ifrs-full:AdjustmentsForUnrealisedForeignExchangeLossesGains
114 Income tax expense recognized in net loss Concept (Monetary) For Period Debit ifrs-full:AdjustmentsForIncomeTaxExpense
115 Income taxes received (paid) Concept (Monetary) For Period Credit ifrs-full:IncomeTaxesPaidClassifiedAsOperatingActivities
116 Tax credit Concept (Monetary) For Period Credit cmta:IncomeTaxCreditsReceived
117 Net changes in working capital Abstract cmta:NetChangesInWorkingCapitalAbstract
118 Sales tax and other receivables Concept (Monetary) For Period Credit cmta:IncreaseDecreaseInSalesTaxAndOtherReceivable
119 Income tax and tax credits receivable Concept (Monetary) For Period Credit cmta:IncreaseDecreaseInIncomeTaxAndInvestmentTaxCreditsReceivable
120 Prepaid expenses Concept (Monetary) For Period Credit cmta:IncreaseDecreaseInPrepaidExpenses
121 Accounts payable and accrued liabilities Concept (Monetary) For Period Debit cmta:IncreaseDecreaseInAccountsPayableAndAccruedLiabilities
122 Net operating cash flows Concept (Monetary) For Period ifrs-full:CashFlowsFromUsedInOperatingActivities
123 Investing activities Abstract ifrs-full:CashFlowsFromUsedInInvestingActivitiesAbstract
124 Interest income received Concept (Monetary) For Period Debit ifrs-full:InterestReceivedClassifiedAsInvestingActivities
125 Acquisition of short-term investments Concept (Monetary) For Period Credit ifrs-full:PurchaseOfInvestmentsOtherThanInvestmentsAccountedForUsingEquityMethod
126 Maturity of short-term investments Concept (Monetary) For Period Debit ifrs-full:ProceedsFromSalesOrMaturityOfFinancialInstrumentsClassifiedAsInvestingActivities
127 Acquisition of property and equipment Concept (Monetary) For Period Credit ifrs-full:PurchaseOfPropertyPlantAndEquipmentClassifiedAsInvestingActivities
128 Acquisition of intangible assets Concept (Monetary) For Period Credit ifrs-full:PurchaseOfIntangibleAssetsClassifiedAsInvestingActivities
129 Net investing cash flows Concept (Monetary) For Period Debit ifrs-full:CashFlowsFromUsedInInvestingActivities
130 Financing activities Abstract ifrs-full:CashFlowsFromUsedInFinancingActivitiesAbstract
131 Issuance of common shares Concept (Monetary) For Period Debit ifrs-full:ProceedsFromIssueOfOrdinaryShares
132 Proceeds of public offering Concept (Monetary) For Period Debit cmta:ProceedsFromInitialPublicOffering
133 Issuance costs Concept (Monetary) For Period Credit ifrs-full:PaymentsForShareIssueCosts
134 Issuance of Preferred Shares Concept (Monetary) For Period Debit ifrs-full:ProceedsFromIssueOfPreferenceShares
135 Net financing cash flows Concept (Monetary) For Period Debit ifrs-full:CashFlowsFromUsedInFinancingActivities
136 Net increase (decrease) in cash Concept (Monetary) For Period Debit ifrs-full:IncreaseDecreaseInCashAndCashEquivalentsBeforeEffectOfExchangeRateChanges
137 Cash, beginning of year Concept (Monetary) As Of Debit ifrs-full:CashAndCashEquivalents
138 Effect of exchange rate fluctuations on cash held Concept (Monetary) For Period Debit ifrs-full:EffectOfExchangeRateChangesOnCashAndCashEquivalents
139 Cash, end of year Concept (Monetary) As Of Debit ifrs-full:CashAndCashEquivalents
140 005 - Disclosure - Note 1 - General Information Network

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141 Statement Table [Table] Table

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142 Non-adjusting events after reporting period [axis] Axis ifrs-full:NonadjustingEventsAfterReportingPeriodAxis
143 Non-adjusting events after reporting period [member] Member ifrs-full:NonadjustingEventsMember
144 Agreement with Ipsen [member] Member cmta:AgreementWithIpsenMember
145 Major ordinary share transactions [member] Member ifrs-full:MajorOrdinaryShareTransactionsMember
146 Components of equity [axis] Axis ifrs-full:ComponentsOfEquityAxis
147 Equity [member] Member ifrs-full:EquityMember
148 At the market equity offering [member] Member cmta:AtTheMarketEquityOfferingMember
149 Share premium [member] Member ifrs-full:SharePremiumMember
150 Legal Entity [Axis] Axis dei:LegalEntityAxis
151 Entity [Domain] Member dei:EntityDomain
152 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
153 Disclosure of general information about financial statements [text block] Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfGeneralInformationAboutFinancialStatementsExplanatory
154 006 - Disclosure - Note 2 - Significant Accounting Policies Network

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155 Statement Table [Table] Table

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156 Retrospective application and retrospective restatement [axis] Axis ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
157 Currently stated [member] Member ifrs-full:RestatedMember
158 Increase (decrease) due to corrections of prior period errors [member] Member ifrs-full:FinancialEffectOfCorrectionsOfAccountingErrorsMember
159 Creation date [axis] Axis ifrs-full:CreationDateAxis
160 Default financial statements date [member] Member ifrs-full:DefaultFinancialStatementsDateMember
161 December 31, 2017 [member] Member cmta:December312017Member
162 Classes of intangible assets other than goodwill [axis] Axis ifrs-full:ClassesOfIntangibleAssetsOtherThanGoodwillAxis
163 Intangible assets other than goodwill [member] Member ifrs-full:IntangibleAssetsOtherThanGoodwillMember
164 Computer software [member] Member ifrs-full:ComputerSoftwareMember
165 Copyrights, patents and other industrial property rights, service and operating rights [member] Member ifrs-full:CopyrightsPatentsAndOtherIndustrialPropertyRightsServiceAndOperatingRightsMember
166 Range [axis] Axis ifrs-full:RangeAxis
167 Ranges [member] Member ifrs-full:RangesMember
168 Bottom of range [member] Member ifrs-full:BottomOfRangeMember
169 Top of range [member] Member ifrs-full:TopOfRangeMember
170 Legal Entity [Axis] Axis dei:LegalEntityAxis
171 Entity [Domain] Member dei:EntityDomain
172 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
173 Disclosure of significant accounting policies [text block] Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfSummaryOfSignificantAccountingPoliciesExplanatory
174 007 - Disclosure - Note 3 - Critical Accounting Judgements and Key Sources of Estimation Uncertainty Network

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175 Statement Table [Table] Table

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176 Legal Entity [Axis] Axis dei:LegalEntityAxis
177 Entity [Domain] Member dei:EntityDomain
178 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
179 Disclosure of accounting judgements and estimates [text block] Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfAccountingJudgementsAndEstimatesExplanatory
180 008 - Disclosure - Note 4 - Future Changes in Accounting Policies Network

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181 Statement Table [Table] Table

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182 Legal Entity [Axis] Axis dei:LegalEntityAxis
183 Entity [Domain] Member dei:EntityDomain
184 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
185 Disclosure of expected impact of initial application of new standards or interpretations [text block] Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretations
186 009 - Disclosure - Note 5 - Investments Network

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187 Statement Table [Table] Table

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188 Range [axis] Axis ifrs-full:RangeAxis
189 Ranges [member] Member ifrs-full:RangesMember
190 Bottom of range [member] Member ifrs-full:BottomOfRangeMember
191 Top of range [member] Member ifrs-full:TopOfRangeMember
192 Legal Entity [Axis] Axis dei:LegalEntityAxis
193 Entity [Domain] Member dei:EntityDomain
194 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
195 Disclosure of investments other than investments accounted for using equity method [text block] Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfInvestmentsOtherThanInvestmentsAccountedForUsingEquityMethodExplanatory
196 010 - Disclosure - Note 6 - Intangible Assets Network

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197 Statement Table [Table] Table

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198 Classes of intangible assets other than goodwill [axis] Axis ifrs-full:ClassesOfIntangibleAssetsOtherThanGoodwillAxis
199 Intangible assets other than goodwill [member] Member ifrs-full:IntangibleAssetsOtherThanGoodwillMember
200 Licences [member] Member ifrs-full:LicencesMember
201 Counterparties [axis] Axis ifrs-full:CounterpartiesAxis
202 Counterparties [member] Member ifrs-full:CounterpartiesMember
203 Galderma [member] Member cmta:GaldermaMember
204 Legal Entity [Axis] Axis dei:LegalEntityAxis
205 Entity [Domain] Member dei:EntityDomain
206 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
207 Disclosure of intangible assets [text block] Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfIntangibleAssetsExplanatory
208 011 - Disclosure - Note 7 - Preferred Shares Network

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209 Statement Table [Table] Table

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210 Classes of share capital [axis] Axis ifrs-full:ClassesOfShareCapitalAxis
211 Share capital [member] Member ifrs-full:ClassesOfShareCapitalMember
212 Series C preferred shares [member] Member cmta:SeriesCPreferredSharesMember
213 Series A preferred shares [member] Member cmta:SeriesAPreferredSharesMember
214 Series B preferred shares [member] Member cmta:SeriesBPreferredSharesMember
215 Legal Entity [Axis] Axis dei:LegalEntityAxis
216 Entity [Domain] Member dei:EntityDomain
217 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
218 Disclosure of preferred shares [text block] Concept (Text Block (HTML)) For Period cmta:DisclosureOfPreferredSharesTextBlock
219 012 - Disclosure - Note 8 - Share Capital Network

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220 Statement Table [Table] Table

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221 Non-adjusting events after reporting period [axis] Axis ifrs-full:NonadjustingEventsAfterReportingPeriodAxis
222 Non-adjusting events after reporting period [member] Member ifrs-full:NonadjustingEventsMember
223 Major ordinary share transactions [member] Member ifrs-full:MajorOrdinaryShareTransactionsMember
224 Types of financial liabilities [axis] Axis ifrs-full:TypesOfFinancialLiabilitiesAxis
225 Financial liabilities, type [member] Member ifrs-full:FinancialLiabilitiesTypeMember
226 Advisory costs [member] Member cmta:AdvisoryCostsMember
227 Underwriter fees [member] Member cmta:UnderwriterFeesMember
228 Components of equity [axis] Axis ifrs-full:ComponentsOfEquityAxis
229 Equity [member] Member ifrs-full:EquityMember
230 At the market equity offering [member] Member cmta:AtTheMarketEquityOfferingMember
231 Legal Entity [Axis] Axis dei:LegalEntityAxis
232 Entity [Domain] Member dei:EntityDomain
233 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
234 Disclosure of issued capital [text block] Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfIssuedCapitalExplanatory
235 013 - Disclosure - Note 9 - Share-based Payments Network

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236 Statement Table [Table] Table

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237 Types of share-based payment arrangements [axis] Axis ifrs-full:TypesOfSharebasedPaymentArrangementsAxis
238 Share-based payment arrangements [member] Member ifrs-full:SharebasedPaymentArrangementsMember
239 Employee stock option plan [member[ Member cmta:EmployeeStockOptionPlanMember
240 2017 Omnibus Plan [member] Member cmta:OmnibusPlan2017Member
241 Performance-based stock options granted [member] Member cmta:PerformancebasedStockOptionsGrantedMember
242 Deferred share units (DSUs) [member] Member cmta:DeferredShareUnitsDsusMember
243 Range [axis] Axis ifrs-full:RangeAxis
244 Ranges [member] Member ifrs-full:RangesMember
245 Top of range [member] Member ifrs-full:TopOfRangeMember
246 Legal Entity [Axis] Axis dei:LegalEntityAxis
247 Entity [Domain] Member dei:EntityDomain
248 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
249 Disclosure of share-based payment arrangements [text block] Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfSharebasedPaymentArrangementsExplanatory
250 014 - Disclosure - Note 10 - Loss Per Share Network

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251 Statement Table [Table] Table

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252 Legal Entity [Axis] Axis dei:LegalEntityAxis
253 Entity [Domain] Member dei:EntityDomain
254 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
255 Earnings per share [text block] Concept (Text Block (HTML)) For Period ifrs-full:EarningsPerShareExplanatory
256 015 - Disclosure - Note 11 - Income Taxes Network

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257 Statement Table [Table] Table

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258 Legal Entity [Axis] Axis dei:LegalEntityAxis
259 Entity [Domain] Member dei:EntityDomain
260 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
261 Disclosure of income tax [text block] Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfIncomeTaxExplanatory
262 016 - Disclosure - Note 12 - Additional Information on the Consolidated Statements of Net Loss and Comprehensive Loss Network

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263 Statement Table [Table] Table

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264 Legal Entity [Axis] Axis dei:LegalEntityAxis
265 Entity [Domain] Member dei:EntityDomain
266 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
267 Disclosure of additional information on the consolidated statements of net loss and comprehensive loss [text block] Concept (Text Block (HTML)) For Period cmta:DisclosureOfAdditionalInformationOnTheConsolidatedStatementsOfNetLossAndComprehensiveLossTextBlock
268 017 - Disclosure - Note 13 - Financial Expenses Network

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269 Statement Table [Table] Table

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270 Legal Entity [Axis] Axis dei:LegalEntityAxis
271 Entity [Domain] Member dei:EntityDomain
272 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
273 Disclosure of finance income (cost) [text block] Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfFinanceIncomeExpenseExplanatory
274 018 - Disclosure - Note 14 - Commitments and Contingencies Network

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275 Statement Table [Table] Table

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276 Arrangements involving legal form of lease [axis] Axis ifrs-full:ArrangementsInvolvingLegalFormOfLeaseAxis
277 Arrangements involving legal form of lease [member] Member ifrs-full:ArrangementsInvolvingLegalFormOfLeaseMember
278 Head office lease in Montreal, Quebec, Canada [member] Member cmta:HeadOfficeLeaseInMontrealQuebecCanadaMember
279 Office space in Newton Massachusetts [member] Member cmta:OfficeSpaceInNewtonMassachusettsMember
280 Non-adjusting events after reporting period [axis] Axis ifrs-full:NonadjustingEventsAfterReportingPeriodAxis
281 Non-adjusting events after reporting period [member] Member ifrs-full:NonadjustingEventsMember
282 Entering into significant commitments or contingent liabilities [member] Member ifrs-full:EnteringIntoSignificantCommitmentsOrContingentLiabilitiesMember
283 Counterparties [axis] Axis ifrs-full:CounterpartiesAxis
284 Counterparties [member] Member ifrs-full:CounterpartiesMember
285 Hoffman-La Roche [member] Member cmta:HoffmanlaRocheMember
286 Thomas Jefferson University [member] Member cmta:ThomasJeffersonUniversityMember
287 Yamaguchi University [member] Member cmta:YamaguchiUniversityMember
288 Galderma [member] Member cmta:GaldermaMember
289 Legal Entity [Axis] Axis dei:LegalEntityAxis
290 Entity [Domain] Member dei:EntityDomain
291 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
292 Disclosure of commitments and contingent liabilities [text block] Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfCommitmentsAndContingentLiabilitiesExplanatory
293 019 - Disclosure - Note 15 - Related Party Transactions Network

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294 Statement Table [Table] Table

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295 Categories of related parties [axis] Axis ifrs-full:CategoriesOfRelatedPartiesAxis
296 Entity's total for related parties [member] Member ifrs-full:EntitysTotalForRelatedPartiesMember
297 Company controlled by an investor [member] Member cmta:CompanyControlledByAnInvestorMember
298 Key management personnel of entity or parent [member] Member ifrs-full:KeyManagementPersonnelOfEntityOrParentMember
299 Legal Entity [Axis] Axis dei:LegalEntityAxis
300 Entity [Domain] Member dei:EntityDomain
301 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
302 Disclosure of related party [text block] Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfRelatedPartyExplanatory
303 020 - Disclosure - Note 16 - Financial Instruments Network

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304 Statement Table [Table] Table

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305 Legal Entity [Axis] Axis dei:LegalEntityAxis
306 Entity [Domain] Member dei:EntityDomain
307 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
308 Disclosure of financial instruments [text block] Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfFinancialInstrumentsExplanatory
309 021 - Disclosure - Note 17 - Operating Segments Network

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310 Statement Table [Table] Table

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311 Legal Entity [Axis] Axis dei:LegalEntityAxis
312 Entity [Domain] Member dei:EntityDomain
313 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
314 Disclosure of operating segments [text block] Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfOperatingSegmentsExplanatory
315 022 - Disclosure - Note 18 - Subsequent Events Network

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316 Statement Table [Table] Table

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317 Arrangements involving legal form of lease [axis] Axis ifrs-full:ArrangementsInvolvingLegalFormOfLeaseAxis
318 Arrangements involving legal form of lease [member] Member ifrs-full:ArrangementsInvolvingLegalFormOfLeaseMember
319 Head office lease in Montreal, Quebec, Canada [member] Member cmta:HeadOfficeLeaseInMontrealQuebecCanadaMember
320 Office space in Newton Massachusetts [member] Member cmta:OfficeSpaceInNewtonMassachusettsMember
321 Non-adjusting events after reporting period [axis] Axis ifrs-full:NonadjustingEventsAfterReportingPeriodAxis
322 Non-adjusting events after reporting period [member] Member ifrs-full:NonadjustingEventsMember
323 Entering into significant commitments or contingent liabilities [member] Member ifrs-full:EnteringIntoSignificantCommitmentsOrContingentLiabilitiesMember
324 Major ordinary share transactions [member] Member ifrs-full:MajorOrdinaryShareTransactionsMember
325 Agreement with Ipsen [member] Member cmta:AgreementWithIpsenMember
326 Ordinary transactions [member] Member cmta:OrdinaryTransactionsMember
327 Types of share-based payment arrangements [axis] Axis ifrs-full:TypesOfSharebasedPaymentArrangementsAxis
328 Share-based payment arrangements [member] Member ifrs-full:SharebasedPaymentArrangementsMember
329 Deferred share units (DSUs) [member] Member cmta:DeferredShareUnitsDsusMember
330 Legal Entity [Axis] Axis dei:LegalEntityAxis
331 Entity [Domain] Member dei:EntityDomain
332 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
333 Disclosure of events after reporting period [text block] Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfEventsAfterReportingPeriodExplanatory
334 023 - Disclosure - Significant Accounting Policies (Policies) Network

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335 Statement Table [Table] Table

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336 Legal Entity [Axis] Axis dei:LegalEntityAxis
337 Entity [Domain] Member dei:EntityDomain
338 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
339 Discloure of Significant Accounting Policies Abstract cmta:DisclosureOfSignificantAccountingPoliciesAbstract
340 Description of accounting policy for statement of compliance and basis of preparation [text block] Concept (Text Block (HTML)) For Period cmta:DescriptionOfAccountingPolicyForStatementOfComplianceAndBasisOfPreparationTextBlock
341 Description of accounting policy for basis of consolidation [text block] Concept (Text Block (HTML)) For Period cmta:DescriptionOfAccountingPolicyForBasisOfConsolidationTextBlock
342 Description of accounting policy for functional currency [text block] Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForFunctionalCurrencyExplanatory
343 Description of accounting policy for foreign currency translation [text block] Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForForeignCurrencyTranslationExplanatory
344 Description of accounting policy for restricted cash and cash equivalents [text block] Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForRestrictedCashAndCashEquivalentsExplanatory
345 Description of accounting policy for investments other than investments accounted for using equity method [text block] Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForInvestmentsOtherThanInvestmentsAccountedForUsingEquityMethodExplanatory
346 Description of accounting policy for property, plant and equipment [text block] Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForPropertyPlantAndEquipmentExplanatory
347 Description of accounting policy for intangible assets other than goodwill [text block] Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForIntangibleAssetsOtherThanGoodwillExplanatory
348 Description of accounting policy for impairment of non-financial assets [text block] Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForImpairmentOfNonfinancialAssetsExplanatory
349 Description of accounting policy for government grants [text block] Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForGovernmentGrants
350 Description of accounting policy for share-based payment transactions [text block] Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForSharebasedPaymentTransactionsExplanatory
351 Description of accounting policy for issued capital [text block] Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForIssuedCapitalExplanatory
352 Description of accounting policy for income tax [text block] Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForIncomeTaxExplanatory
353 Description of accounting policy for earnings per share [text block] Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForEarningsPerShareExplanatory
354 Description of accounting policy for employee benefits [text block] Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForEmployeeBenefitsExplanatory
355 Description of accounting policy for interest income and expense [text block] Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForInterestIncomeAndExpenseExplanatory
356 Description of accounting policy for financial instruments [text block] Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForFinancialInstrumentsExplanatory
357 Description of accounting policy for leases [text block] Concept (Text Block (HTML)) For Period ifrs-full:DescriptionOfAccountingPolicyForLeasesExplanatory
358 024 - Disclosure - Note 2 - Significant Accounting Policies (Tables) Network

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359 Statement Table [Table] Table

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360 Legal Entity [Axis] Axis dei:LegalEntityAxis
361 Entity [Domain] Member dei:EntityDomain
362 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
363 Disclosure of useful lives or depreciation rates, property, plant and equipment [text block] Concept (Text Block (HTML)) For Period cmta:DisclosureOfUsefulLivesOrDepreciationRatesPropertyPlantAndEquipmentTextBlock
364 025 - Disclosure - Note 5 - Investments (Tables) Network

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365 Statement Table [Table] Table

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366 Legal Entity [Axis] Axis dei:LegalEntityAxis
367 Entity [Domain] Member dei:EntityDomain
368 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
369 Disclosure of term deposits [text block] Concept (Text Block (HTML)) For Period cmta:DisclosureOfTermDepositsTextBlock
370 026 - Disclosure - Note 6 - Intangible Assets (Tables) Network

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371 Statement Table [Table] Table

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372 Legal Entity [Axis] Axis dei:LegalEntityAxis
373 Entity [Domain] Member dei:EntityDomain
374 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
375 Disclosure of detailed information about intangible assets [text block] Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfDetailedInformationAboutIntangibleAssetsExplanatory
376 027 - Disclosure - Note 7 - Preferred Shares (Tables) Network

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377 Statement Table [Table] Table

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378 Legal Entity [Axis] Axis dei:LegalEntityAxis
379 Entity [Domain] Member dei:EntityDomain
380 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
381 Disclosure of changes in Preferred Shares and Embedded Derivatives [text block] Concept (Text Block (HTML)) For Period cmta:DisclosureOfChangesInPreferredSharesAndEmbeddedDerivativesTextBlock
382 Disclosure of assumptions used to determine the fair value of embedded derivative [text block] Concept (Text Block (HTML)) For Period cmta:DisclosureOfAssumptionsUsedToDetermineTheFairValueOfEmbeddedDerivativeTextBlock
383 028 - Disclosure - Note 9 - Share-based Payments (Tables) Network

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384 Statement Table [Table] Table

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385 Legal Entity [Axis] Axis dei:LegalEntityAxis
386 Entity [Domain] Member dei:EntityDomain
387 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
388 Disclosure of number and weighted average exercise prices of share options [text block] Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfNumberAndWeightedAverageExercisePricesOfShareOptionsExplanatory
389 Disclosure of range of exercise prices of outstanding share options [text block] Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfRangeOfExercisePricesOfOutstandingShareOptionsExplanatory
390 Disclosure of indirect measurement of fair value of goods or services received, share options granted during period [text block] Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfIndirectMeasurementOfFairValueOfGoodsOrServicesReceivedShareOptionsGrantedDuringPeriodExplanatory
391 029 - Disclosure - Note 11 - Income Taxes (Tables) Network

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392 Statement Table [Table] Table

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393 Legal Entity [Axis] Axis dei:LegalEntityAxis
394 Entity [Domain] Member dei:EntityDomain
395 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
396 Disclosure of reconciliation of average effective tax expenses and applicable tax expenses [text block] Concept (Text Block (HTML)) For Period cmta:DisclosureOfReconciliationOfAverageEffectiveTaxExpensesAndApplicableTaxExpensesTextBlock
397 Disclosure of temporary difference, unused tax losses and unused tax credits [text block] Concept (Text Block (HTML)) For Period ifrs-full:DisclosureOfTemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsExplanatory
398 Disclosure of loss carryforwards, unclaimed deductions and credits available for carryforwards [text block] Concept (Text Block (HTML)) For Period cmta:DisclosureOfLossCarryforwardsUnclaimedDeductionsAndCreditsAvailableForCarryforwardsTextBlock
399 030 - Disclosure - Note 12 - Additional Information on the Consolidated Statements of Net Loss and Comprehensive Loss (Tables) Network

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400 Statement Table [Table] Table

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401 Legal Entity [Axis] Axis dei:LegalEntityAxis
402 Entity [Domain] Member dei:EntityDomain
403 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
404 Disclosure of supplemental information of comprehensive income (loss) [text block] Concept (Text Block (HTML)) For Period cmta:DisclosureOfSupplementalInformationOfComprehensiveIncomeLossTextBlock
405 031 - Disclosure - Note 13 - Financial Expenses (Tables) Network

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406 Statement Table [Table] Table

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407 Legal Entity [Axis] Axis dei:LegalEntityAxis
408 Entity [Domain] Member dei:EntityDomain
409 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
410 Disclosure of total financial expenses [text block] Concept (Text Block (HTML)) For Period cmta:DisclosureOfTotalFinancialExpensesTextBlock
411 032 - Disclosure - Note 14 - Commitments and Contingencies (Tables) Network

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412 Statement Table [Table] Table

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413 Legal Entity [Axis] Axis dei:LegalEntityAxis
414 Entity [Domain] Member dei:EntityDomain
415 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
416 Disclosure of contractual obligations [text block] Concept (Text Block (HTML)) For Period cmta:DisclosureOfContractualObligationsTextBlock
417 033 - Disclosure - Note 15 - Related Party Transactions (Tables) Network

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418 Statement Table [Table] Table

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419 Legal Entity [Axis] Axis dei:LegalEntityAxis
420 Entity [Domain] Member dei:EntityDomain
421 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
422 Disclosure of compensation for key management personnel [text block] Concept (Text Block (HTML)) For Period cmta:DisclosureOfCompensationForKeyManagementPersonnelTextBlock
423 034 - Disclosure - Note 16 - Financial Instruments (Tables) Network

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424 Statement Table [Table] Table

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425 Legal Entity [Axis] Axis dei:LegalEntityAxis
426 Entity [Domain] Member dei:EntityDomain
427 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
428 Disclosure of currency risk [text block] Concept (Text Block (HTML)) For Period cmta:DisclosureOfCurrencyRiskTextBlock
429 Disclosure of exchange rates Concept (Text Block (HTML)) For Period cmta:DisclosureOfExchangeRates
430 035 - Disclosure - Note 1 - General Information (Details Textual) Network

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431 Statement Table [Table] Table

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432 Non-adjusting events after reporting period [axis] Axis ifrs-full:NonadjustingEventsAfterReportingPeriodAxis
433 Non-adjusting events after reporting period [member] Member ifrs-full:NonadjustingEventsMember
434 Agreement with Ipsen [member] Member cmta:AgreementWithIpsenMember
435 Major ordinary share transactions [member] Member ifrs-full:MajorOrdinaryShareTransactionsMember
436 Components of equity [axis] Axis ifrs-full:ComponentsOfEquityAxis
437 Equity [member] Member ifrs-full:EquityMember
438 At the market equity offering [member] Member cmta:AtTheMarketEquityOfferingMember
439 Share premium [member] Member ifrs-full:SharePremiumMember
440 Legal Entity [Axis] Axis dei:LegalEntityAxis
441 Entity [Domain] Member dei:EntityDomain
442 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
443 Plan of arrangement, purchase price Concept (Share) As Of cmta:PlanOfArrangementPurchasePrice
444 Plan of arrangement, contingent value right Concept (Share) As Of cmta:PlanOfArrangementContingentValueRight
445 Plan of arrangement, maximum transaction value Concept (Monetary) As Of Credit cmta:PlanOfArrangementMaximumTransactionValue
446 Stock split, conversion ratio Concept (Pure) For Period cmta:StockSplitConversionRatio
447 Issuance of common stock Concept (Shares) For Period cmta:IssuanceOfCommonStock
448 Shares issued, price per share Concept (Share) As Of cmta:SharesIssuedPricePerShare
449 Proceeds from initial public offering Concept (Monetary) For Period Debit cmta:ProceedsFromInitialPublicOffering
450 Sale of stock maximum offering value Concept (Monetary) As Of Credit cmta:SaleOfStockMaximumOfferingValue
451 Equity issuance commission percentage Concept (Percent) As Of cmta:EquityIssuanceCommissionPercentage
452 Issue of equity Concept (Monetary) For Period Credit ifrs-full:IssueOfEquity
453 Total comprehensive income Concept (Monetary) For Period Credit ifrs-full:ComprehensiveIncome
454 Retained earnings Concept (Monetary) As Of Credit ifrs-full:RetainedEarnings
455 Convertible instrument, conversion ratio Concept (Pure) For Period cmta:ConvertibleInstrumentConversionRatio
456 Reduction of Deficit Concept (Monetary) For Period Credit cmta:ReductionOfDeficit
457 Increase (decrease) through excess of carrying value of preferred shares and embedded derivatives liabilities over the stated capital of the preferred shares Concept (Monetary) For Period Credit cmta:IncreaseDecreaseThroughExcessOfCarryingValueOfPreferredSharesAndEmbeddedDerivativesLiabilitiesOverTheStatedCapitalOfThePreferredShares
458 Net cash flows from (used in) operating activities Concept (Monetary) For Period ifrs-full:CashFlowsFromUsedInOperatingActivities
459 036 - Disclosure - Note 2 - Significant Accounting Policies (Details Textual) Network

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460 Statement Table [Table] Table

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461 Retrospective application and retrospective restatement [axis] Axis ifrs-full:RetrospectiveApplicationAndRetrospectiveRestatementAxis
462 Currently stated [member] Member ifrs-full:RestatedMember
463 Increase (decrease) due to corrections of prior period errors [member] Member ifrs-full:FinancialEffectOfCorrectionsOfAccountingErrorsMember
464 Creation date [axis] Axis ifrs-full:CreationDateAxis
465 Default financial statements date [member] Member ifrs-full:DefaultFinancialStatementsDateMember
466 December 31, 2017 [member] Member cmta:December312017Member
467 Classes of intangible assets other than goodwill [axis] Axis ifrs-full:ClassesOfIntangibleAssetsOtherThanGoodwillAxis
468 Intangible assets other than goodwill [member] Member ifrs-full:IntangibleAssetsOtherThanGoodwillMember
469 Computer software [member] Member ifrs-full:ComputerSoftwareMember
470 Copyrights, patents and other industrial property rights, service and operating rights [member] Member ifrs-full:CopyrightsPatentsAndOtherIndustrialPropertyRightsServiceAndOperatingRightsMember
471 Range [axis] Axis ifrs-full:RangeAxis
472 Ranges [member] Member ifrs-full:RangesMember
473 Bottom of range [member] Member ifrs-full:BottomOfRangeMember
474 Top of range [member] Member ifrs-full:TopOfRangeMember
475 Legal Entity [Axis] Axis dei:LegalEntityAxis
476 Entity [Domain] Member dei:EntityDomain
477 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
478 Current prepaid expenses Concept (Monetary) As Of Debit ifrs-full:CurrentPrepaidExpenses
479 Amortisation method, intangible assets other than goodwill Concept (Text/String) For Period ifrs-full:AmortisationMethodIntangibleAssetsOtherThanGoodwill
480 Non-current prepaid expenses Concept (Monetary) As Of Debit cmta:NoncurrentPrepaidExpenses
481 037 - Disclosure - Note 2 - Significant Accounting Policies - Estimated Useful Lives (Details) Network

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482 Statement Table [Table] Table

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483 Classes of property, plant and equipment [axis] Axis ifrs-full:ClassesOfPropertyPlantAndEquipmentAxis
484 Property, plant and equipment [member] Member ifrs-full:PropertyPlantAndEquipmentMember
485 Computer equipment [member] Member ifrs-full:ComputerEquipmentMember
486 Office equipment [member] Member ifrs-full:OfficeEquipmentMember
487 Furniture [member] Member cmta:FurnitureMember
488 Leasehold improvements [member] Member ifrs-full:LeaseholdImprovementsMember
489 Legal Entity [Axis] Axis dei:LegalEntityAxis
490 Entity [Domain] Member dei:EntityDomain
491 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
492 Estimated useful lives Concept (Text/String) For Period ifrs-full:UsefulLivesOrDepreciationRatesPropertyPlantAndEquipment
493 038 - Disclosure - Note 5 - Investments (Details Textual) Network

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494 Statement Table [Table] Table

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495 Range [axis] Axis ifrs-full:RangeAxis
496 Ranges [member] Member ifrs-full:RangesMember
497 Bottom of range [member] Member ifrs-full:BottomOfRangeMember
498 Top of range [member] Member ifrs-full:TopOfRangeMember
499 Legal Entity [Axis] Axis dei:LegalEntityAxis
500 Entity [Domain] Member dei:EntityDomain
501 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
502 Term deposits, interest rate Concept (Percent) For Period cmta:TermDepositsInterestRate
503 039 - Disclosure - Note 5 - Investments - Term Deposits (Details) Network

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504 Statement Table [Table] Table

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505 Legal Entity [Axis] Axis dei:LegalEntityAxis
506 Entity [Domain] Member dei:EntityDomain
507 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
508 Short-term investments Concept (Monetary) As Of Debit ifrs-full:ShorttermDepositsNotClassifiedAsCashEquivalents
509 Long-term investments Concept (Monetary) As Of Debit ifrs-full:LongtermDeposits
510 Total deposit assets Concept (Monetary) As Of Debit cmta:TotalDepositAssets
511 040 - Disclosure - Note 6 - Intangible Assets (Details Textual) Network

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512 Statement Table [Table] Table

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513 Classes of intangible assets other than goodwill [axis] Axis ifrs-full:ClassesOfIntangibleAssetsOtherThanGoodwillAxis
514 Intangible assets other than goodwill [member] Member ifrs-full:IntangibleAssetsOtherThanGoodwillMember
515 Licences [member] Member ifrs-full:LicencesMember
516 Counterparties [axis] Axis ifrs-full:CounterpartiesAxis
517 Counterparties [member] Member ifrs-full:CounterpartiesMember
518 Galderma [member] Member cmta:GaldermaMember
519 Legal Entity [Axis] Axis dei:LegalEntityAxis
520 Entity [Domain] Member dei:EntityDomain
521 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
522 Purchase of intangible assets Concept (Monetary) For Period Credit ifrs-full:PurchaseOfIntangibleAssetsClassifiedAsInvestingActivities
523 041 - Disclosure - Note 6 - Intangible Assets - Intangible Assets (Details) Network

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524 Statement Table [Table] Table

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525 Carrying amount, accumulated depreciation, amortisation and impairment and gross carrying amount [axis] Axis ifrs-full:CarryingAmountAccumulatedDepreciationAmortisationAndImpairmentAndGrossCarryingAmountAxis
526 Carrying amount [member] Member ifrs-full:CarryingAmountMember
527 Gross carrying amount [member] Member ifrs-full:GrossCarryingAmountMember
528 Accumulated depreciation and amortisation [member] Member ifrs-full:AccumulatedDepreciationAndAmortisationMember
529 Legal Entity [Axis] Axis dei:LegalEntityAxis
530 Entity [Domain] Member dei:EntityDomain
531 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
532 Intangible assets other than goodwill at end of period Concept (Monetary) As Of Debit ifrs-full:IntangibleAssetsOtherThanGoodwill
533 Additions Concept (Monetary) For Period Debit ifrs-full:AdditionsOtherThanThroughBusinessCombinationsIntangibleAssetsOtherThanGoodwill
534 Amortization Concept (Monetary) For Period ifrs-full:AmortisationIntangibleAssetsOtherThanGoodwill
535 Intangible assets other than goodwill at end of period Concept (Monetary) As Of Debit ifrs-full:IntangibleAssetsOtherThanGoodwill
536 042 - Disclosure - Note 7 - Preferred Shares (Details Textual) Network

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537 Statement Table [Table] Table

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538 Classes of share capital [axis] Axis ifrs-full:ClassesOfShareCapitalAxis
539 Share capital [member] Member ifrs-full:ClassesOfShareCapitalMember
540 Series C preferred shares [member] Member cmta:SeriesCPreferredSharesMember
541 Series A preferred shares [member] Member cmta:SeriesAPreferredSharesMember
542 Series B preferred shares [member] Member cmta:SeriesBPreferredSharesMember
543 Legal Entity [Axis] Axis dei:LegalEntityAxis
544 Entity [Domain] Member dei:EntityDomain
545 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
546 Proceeds from issue of preference shares Concept (Monetary) For Period Debit ifrs-full:ProceedsFromIssueOfPreferenceShares
547 Number of preferred shares issued during period Concept (Shares) For Period cmta:NumberOfPreferredSharesIssuedDuringPeriod
548 Shares issued, price per share Concept (Share) As Of cmta:SharesIssuedPricePerShare
549 Payments for share issue costs Concept (Monetary) For Period Credit ifrs-full:PaymentsForShareIssueCosts
550 Preferred shares, conversion ratio Concept (Pure) For Period cmta:PreferredSharesConversionRatio
551 Preferred shares, dividend rate Concept (Percent) As Of cmta:PreferredSharesDividendRate
552 Conversion of convertible preferred shares Concept (Shares) For Period cmta:ConversionOfConvertiblePreferredShares
553 Number of shares outstanding at end of period Concept (Shares) As Of ifrs-full:NumberOfSharesOutstanding
554 Embedded derivative, fair value assumption, probability-weighted expected return method, weighted percentage Concept (Percent) For Period cmta:EmbeddedDerivativeFairValueAssumptionProbabilityWeightedExpectedReturnMethodWeightedPercentage
555 Embedded derivative, fair value assumption, Monte Carlo simulation model, weighted percentage Concept (Percent) For Period cmta:EmbeddedDerivativeFairValueAssumptionMonteCarloSimulationModelWeightedPercentage
556 Public Offering Price Concept (Share) As Of cmta:PublicOfferingPrice
557 Total number of shares issued Concept (Shares) As Of ifrs-full:NumberOfSharesIssued
558 043 - Disclosure - Note 7 - Preferred Shares - Changes in Preferred Shares and Embedded Derivatives (Details) Network

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559 Statement Table [Table] Table

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560 Classes of share capital [axis] Axis ifrs-full:ClassesOfShareCapitalAxis
561 Share capital [member] Member ifrs-full:ClassesOfShareCapitalMember
562 Series A preferred shares [member] Member cmta:SeriesAPreferredSharesMember
563 Series B preferred shares [member] Member cmta:SeriesBPreferredSharesMember
564 Series C preferred shares [member] Member cmta:SeriesCPreferredSharesMember
565 Classes of financial instruments [axis] Axis ifrs-full:ClassesOfFinancialInstrumentsAxis
566 Financial instruments, class [member] Member ifrs-full:ClassesOfFinancialInstrumentsMember
567 Embedded derivatives derived from series A preferred shares [member] Member cmta:EmbeddedDerivativesDerivedFromSeriesAPreferredSharesMember
568 Embedded derivatives derived from series B preferred shares [member] Member cmta:EmbeddedDerivativesDerivedFromSeriesBPreferredSharesMember
569 Embedded derivatives derived from series C preferred shares [member] Member cmta:EmbeddedDerivativesDerivedFromSeriesCPreferredSharesMember
570 Legal Entity [Axis] Axis dei:LegalEntityAxis
571 Entity [Domain] Member dei:EntityDomain
572 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
573 Balance Concept (Monetary) As Of Credit cmta:PreferredSharesValueOutstanding
574 Accretion during the year Concept (Monetary) For Period Credit cmta:PreferredSharesAccretion
575 Loss on re-measurement at fair value Concept (Monetary) For Period Credit cmta:PreferredSharesGainLossOnRemeasurementAtFairValue
576 Issuance of preferred shares Concept (Monetary) For Period Credit cmta:IssuanceOfPreferredShares
577 Transaction costs Concept (Monetary) For Period Debit cmta:IssuanceOfPreferredSharesTransactionCosts
578 Original stated capital of preferred shares reclassified as share capital upon conversion Concept (Monetary) For Period Debit cmta:PreferredSharesReclassificationUponConversion
579 Excess reclassified as contributed surplus (total $173,285,855) Concept (Monetary) For Period Credit cmta:PreferredSharesExcessReclassifiedAsContributedSurplus
580 Balance Concept (Monetary) As Of Credit ifrs-full:DerivativeFinancialLiabilities
581 Balance Concept (Monetary) As Of Credit ifrs-full:DerivativeFinancialLiabilities
582 Loss (gain) on re-measurement at fair value Concept (Monetary) For Period Credit cmta:DerivativeRemeasurement
583 Issuance of preferred shares Concept (Monetary) For Period Credit cmta:DerivativesNewIssuance
584 Excess reclassified as contributed surplus (total $173,285,855) Concept (Monetary) For Period Debit cmta:DerivativesExcessReclassifiedAsContributedSurplus
585 Balance Concept (Monetary) As Of Credit cmta:PreferredSharesValueOutstanding
586 044 - Disclosure - Note 7 - Preferred Shares - Changes in Preferred Shares and Embedded Derivatives (Details) (Parentheticals) Network

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587 Statement Table [Table] Table

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588 Classes of share capital [axis] Axis ifrs-full:ClassesOfShareCapitalAxis
589 Share capital [member] Member ifrs-full:ClassesOfShareCapitalMember
590 Series A preferred shares [member] Member cmta:SeriesAPreferredSharesMember
591 Legal Entity [Axis] Axis dei:LegalEntityAxis
592 Entity [Domain] Member dei:EntityDomain
593 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
594 Excess of carrying value of preferred shares and embedded derivatives liabilities, over the stated capital of the preferred shares Concept (Monetary) For Period Credit cmta:IncreaseDecreaseThroughExcessOfCarryingValueOfPreferredSharesAndEmbeddedDerivativesLiabilitiesOverTheStatedCapitalOfThePreferredShares
595 045 - Disclosure - Note 7 - Preferred Shares - Key Assumptions (Details) Network

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596 Statement Table [Table] Table

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597 Classes of share capital [axis] Axis ifrs-full:ClassesOfShareCapitalAxis
598 Share capital [member] Member ifrs-full:ClassesOfShareCapitalMember
599 Series A preferred shares [member] Member cmta:SeriesAPreferredSharesMember
600 Series B preferred shares [member] Member cmta:SeriesBPreferredSharesMember
601 Series C preferred shares [member] Member cmta:SeriesCPreferredSharesMember
602 Valuation techniques used in fair value measurement [axis] Axis ifrs-full:ValuationTechniquesUsedInFairValueMeasurementAxis
603 Valuation techniques [member] Member ifrs-full:ValuationTechniquesMember
604 PWERM assumptions [member] Member cmta:PwermAssumptionsMember
605 Monte Carlo assumptions [member] Member cmta:MonteCarloAssumptionsMember
606 Range [axis] Axis ifrs-full:RangeAxis
607 Ranges [member] Member ifrs-full:RangesMember
608 Bottom of range [member] Member ifrs-full:BottomOfRangeMember
609 Top of range [member] Member ifrs-full:TopOfRangeMember
610 Weighted average [member] Member ifrs-full:WeightedAverageMember
611 Legal Entity [Axis] Axis dei:LegalEntityAxis
612 Entity [Domain] Member dei:EntityDomain
613 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
614 Fair value of embedded derivative per share (in dollars per share) Concept (Share) For Period cmta:FairValueOfEmbeddedDerivativePerShare
615 Range of exit multiples Concept (Pure) For Period cmta:FairValueAssumptionRangeOfExitMultiples
616 Time to exit (in years) (Year) Concept (xbrli:durationItemType) For Period cmta:FairValueAssumptionTimeToExit
617 Starting equity value (in millions of $) Concept (Monetary) For Period Credit cmta:FairValueAssumptionStartingEquityValue
618 Volatility Concept (Percent) For Period cmta:FairValueAssumptionVolatility
619 046 - Disclosure - Note 8 - Share Capital (Details Textual) Network

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620 Statement Table [Table] Table

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621 Non-adjusting events after reporting period [axis] Axis ifrs-full:NonadjustingEventsAfterReportingPeriodAxis
622 Non-adjusting events after reporting period [member] Member ifrs-full:NonadjustingEventsMember
623 Major ordinary share transactions [member] Member ifrs-full:MajorOrdinaryShareTransactionsMember
624 Types of financial liabilities [axis] Axis ifrs-full:TypesOfFinancialLiabilitiesAxis
625 Financial liabilities, type [member] Member ifrs-full:FinancialLiabilitiesTypeMember
626 Advisory costs [member] Member cmta:AdvisoryCostsMember
627 Underwriter fees [member] Member cmta:UnderwriterFeesMember
628 Components of equity [axis] Axis ifrs-full:ComponentsOfEquityAxis
629 Equity [member] Member ifrs-full:EquityMember
630 At the market equity offering [member] Member cmta:AtTheMarketEquityOfferingMember
631 Legal Entity [Axis] Axis dei:LegalEntityAxis
632 Entity [Domain] Member dei:EntityDomain
633 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
634 Stock split, conversion ratio Concept (Pure) For Period cmta:StockSplitConversionRatio
635 Preferred shares, conversion ratio Concept (Pure) For Period cmta:PreferredSharesConversionRatio
636 Conversion of convertible preferred shares Concept (Shares) For Period cmta:ConversionOfConvertiblePreferredShares
637 Issuance of common stock Concept (Shares) For Period cmta:IssuanceOfCommonStock
638 Shares issued, price per share Concept (Share) As Of cmta:SharesIssuedPricePerShare
639 Proceeds from initial public offering Concept (Monetary) For Period Debit cmta:ProceedsFromInitialPublicOffering
640 Legal and other advisory costs Concept (Monetary) For Period Debit cmta:LegalAndOtherAdvisoryCosts
641 Financing costs, legal and other advisory costs Concept (Monetary) For Period Debit cmta:FinancingCostsLegalAndOtherAdvisoryCosts
642 Financing costs, underwriter fees Concept (Monetary) For Period Debit cmta:FinancingCostsUnderwriterFees
643 Total number of shares issued Concept (Shares) As Of ifrs-full:NumberOfSharesIssued
644 Proceeds from issue of ordinary shares, gross Concept (Monetary) For Period Debit cmta:ProceedsFromIssueOfOrdinarySharesGross
645 Payments for share issue costs Concept (Monetary) For Period Credit ifrs-full:PaymentsForShareIssueCosts
646 Sale of stock maximum offering value Concept (Monetary) As Of Credit cmta:SaleOfStockMaximumOfferingValue
647 Equity issuance commission percentage Concept (Percent) As Of cmta:EquityIssuanceCommissionPercentage
648 Issue of equity Concept (Monetary) For Period Credit ifrs-full:IssueOfEquity
649 047 - Disclosure - Note 9 - Share-based Payments (Details Textual) Network

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650 Statement Table [Table] Table

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651 Types of share-based payment arrangements [axis] Axis ifrs-full:TypesOfSharebasedPaymentArrangementsAxis
652 Share-based payment arrangements [member] Member ifrs-full:SharebasedPaymentArrangementsMember
653 Employee stock option plan [member[ Member cmta:EmployeeStockOptionPlanMember
654 2017 Omnibus Plan [member] Member cmta:OmnibusPlan2017Member
655 Performance-based stock options granted [member] Member cmta:PerformancebasedStockOptionsGrantedMember
656 Deferred share units (DSUs) [member] Member cmta:DeferredShareUnitsDsusMember
657 Range [axis] Axis ifrs-full:RangeAxis
658 Ranges [member] Member ifrs-full:RangesMember
659 Top of range [member] Member ifrs-full:TopOfRangeMember
660 Legal Entity [Axis] Axis dei:LegalEntityAxis
661 Entity [Domain] Member dei:EntityDomain
662 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
663 Number of share options available for issuance Concept (Shares) As Of cmta:NumberOfShareOptionsAvailableForIssuance
664 Number of share options outstanding in share-based payment arrangement at end of period Concept (Decimal) As Of ifrs-full:NumberOfOutstandingShareOptions
665 Number of share options available for issuance, increase, lower limit, percentage of common shares outstanding Concept (Percent) For Period cmta:NumberOfShareOptionsAvailableForIssuanceIncreaseLowerLimitPercentageOfCommonSharesOutstanding
666 Number of share options available for issuance, increase, lower limit, shares Concept (Shares) For Period cmta:NumberOfShareOptionsAvailableForIssuanceIncreaseLowerLimitShares
667 Share-based compensation arrangement, options, expiration period Concept (xbrli:durationItemType) For Period cmta:SharebasedCompensationArrangementOptionsExpirationPeriod
668 Share-based compensation arrangement, time-based options, vesting period Concept (xbrli:durationItemType) For Period cmta:SharebasedCompensationArrangementTimeBasedOptionsVestingPeriod
669 Share-based compensation arrangement, time-based options, vesting percentage, after one year with monthly vesting over the subsequent 36 months Concept (Percent) For Period cmta:SharebasedCompensationArrangementTimeBasedOptionsVestingPercentageAfterOneYearWithMonthlyVestingOverTheSubsequent36Months
670 Expense from share-based payment transactions with employees Concept (Monetary) For Period Debit ifrs-full:ExpenseFromSharebasedPaymentTransactionsWithEmployees
671 Expense from share-based payment transactions with employees, allocated to general and administrative expenses Concept (Monetary) For Period Debit cmta:ExpenseFromSharebasedPaymentTransactionsWithEmployeesAllocatedToGeneralAndAdministrativeExpenses
672 Expense from share-based payment transactions with employees, allocated to research and development expenses Concept (Monetary) For Period Debit cmta:ExpenseFromSharebasedPaymentTransactionsWithEmployeesAllocatedToResearchAndDevelopmentExpenses
673 Unrecognized share-based compensation expense, net of related forfeiture estimates Concept (Monetary) As Of Debit cmta:UnrecognizedSharebasedCompensationExpenseNetOfRelatedForfeitureEstimates
674 Unrecognized share-based compensation expense, period for recognition Concept (xbrli:durationItemType) For Period cmta:UnrecognizedSharebasedCompensationExpensePeriodForRecognition
675 Unrecognized share-based compensation expense Concept (Monetary) As Of Debit cmta:UnrecognizedSharebasedCompensationExpense
676 Number of other equity instruments granted in share-based payment arrangement Concept (Decimal) For Period ifrs-full:NumberOfInstrumentsOtherEquityInstrumentsGranted
677 Weighted average exercise price of other equity instruments granted in share-based payment arrangement Concept (Monetary) For Period ifrs-full:WeightedAverageExercisePriceOfOtherEquityInstrumentsGrantedInSharebasedPaymentArrangement
678 048 - Disclosure - Note 9 - Share-based Payments - Number of Stock Options Outstanding (Details) Network

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679 Statement Table [Table] Table

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680 Legal Entity [Axis] Axis dei:LegalEntityAxis
681 Entity [Domain] Member dei:EntityDomain
682 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
683 Balance at beginning of year, options Concept (Decimal) As Of ifrs-full:NumberOfOutstandingShareOptions
684 Balance at beginning of year, weighted average exercise price Concept (Monetary) As Of ifrs-full:WeightedAverageExercisePriceOfShareOptionsOutstandingInSharebasedPaymentArrangement
685 Grant (number of stock options) Concept (Decimal) For Period ifrs-full:NumberOfShareOptionsGrantedInSharebasedPaymentArrangement
686 Issued during the year, weighted average exercise price Concept (Monetary) For Period ifrs-full:WeightedAverageExercisePriceOfShareOptionsGrantedInSharebasedPaymentArrangement
687 Exercised during the year, options Concept (Decimal) For Period ifrs-full:NumberOfShareOptionsExercisedInSharebasedPaymentArrangement
688 Exercised during the year, weighted average exercise price Concept (Monetary) For Period ifrs-full:WeightedAverageExercisePriceOfShareOptionsExercisedInSharebasedPaymentArrangement
689 Forfeited during the year, options Concept (Decimal) For Period ifrs-full:NumberOfShareOptionsExpiredInSharebasedPaymentArrangement
690 Forfeited during the year, weighted average exercise price Concept (Monetary) For Period ifrs-full:WeightedAverageExercisePriceOfShareOptionsExpiredInSharebasedPaymentArrangement
691 Balance at end of period, options Concept (Decimal) As Of ifrs-full:NumberOfOutstandingShareOptions
692 Balance at end of period, weighted average exercise price Concept (Monetary) As Of ifrs-full:WeightedAverageExercisePriceOfShareOptionsOutstandingInSharebasedPaymentArrangement
693 049 - Disclosure - Note 9 - Share-based Payments - Summary of Outstanding Stock Options (Details) Network

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694 Statement Table [Table] Table

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695 Range [axis] Axis ifrs-full:RangeAxis
696 Ranges [member] Member ifrs-full:RangesMember
697 Bottom of range [member] Member ifrs-full:BottomOfRangeMember
698 Top of range [member] Member ifrs-full:TopOfRangeMember
699 Ranges of exercise prices for outstanding share options [axis] Axis ifrs-full:RangesOfExercisePricesForOutstandingShareOptionsAxis
700 Ranges of exercise prices for outstanding share options [member] Member ifrs-full:RangesOfExercisePricesForOutstandingShareOptionsMember
701 Range 1 [member] Member cmta:Range1Member
702 Range 2 [member] Member cmta:Range2Member
703 Range 3 [member] Member cmta:Range3Member
704 Range 4 [member] Member cmta:Range4Member
705 Range 5 [member] Member cmta:Range5Member
706 Range 6 [member] Member cmta:Range6Member
707 Range 7 [member] Member cmta:Range7Member
708 Range 8 [member] Member cmta:Range8Member
709 Legal Entity [Axis] Axis dei:LegalEntityAxis
710 Entity [Domain] Member dei:EntityDomain
711 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
712 Exercise price Concept (Monetary) As Of ifrs-full:ExercisePriceOfOutstandingShareOptions
713 Number of stock options outstanding Concept (Decimal) As Of ifrs-full:NumberOfOutstandingShareOptions
714 Weighted average remaining contractual life Concept (Decimal) As Of ifrs-full:WeightedAverageRemainingContractualLifeOfOutstandingShareOptions
715 Weighted average remaining exercise price Concept (Monetary) As Of ifrs-full:WeightedAverageExercisePriceOfShareOptionsOutstandingInSharebasedPaymentArrangement
716 Number of exercisable stock options Concept (Decimal) As Of ifrs-full:NumberOfShareOptionsExercisableInSharebasedPaymentArrangement
717 Weighted average exercise price Concept (Monetary) As Of ifrs-full:WeightedAverageExercisePriceOfShareOptionsExercisableInSharebasedPaymentArrangement
718 050 - Disclosure - Note 9 - Share-based Payments - Fair Value Assumptions (Details) Network

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719 Statement Table [Table] Table

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720 Legal Entity [Axis] Axis dei:LegalEntityAxis
721 Entity [Domain] Member dei:EntityDomain
722 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
723 Grant (number of stock options) Concept (Decimal) For Period ifrs-full:NumberOfShareOptionsGrantedInSharebasedPaymentArrangement
724 Weighted average fair value of stock options (in dollars per share) Concept (Share) As Of cmta:WeightedAverageFairValueAtMeasurementDateShareOptionsGrantedPerShare
725 Weighted average exercise price Concept (Monetary) For Period ifrs-full:ExercisePriceShareOptionsGranted
726 Share price Concept (Monetary) For Period ifrs-full:WeightedAverageSharePriceShareOptionsGranted
727 Risk-free interest rate Concept (Percent) For Period ifrs-full:DescriptionOfRiskFreeInterestRateShareOptionsGranted
728 Expected dividend yield Concept (Percent) For Period ifrs-full:ExpectedDividendAsPercentageShareOptionsGranted
729 Volatility factor Concept (Percent) For Period ifrs-full:DescriptionOfExpectedVolatilityShareOptionsGranted
730 Expected life (in years) Concept (Decimal) For Period ifrs-full:DescriptionOfOptionLifeShareOptionsGranted
731 051 - Disclosure - Note 11 - Income Taxes (Details Textual) Network

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732 Statement Table [Table] Table

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733 Legal Entity [Axis] Axis dei:LegalEntityAxis
734 Entity [Domain] Member dei:EntityDomain
735 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
736 Applicable tax rate Concept (Percent) For Period ifrs-full:ApplicableTaxRate
737 052 - Disclosure - Note 11 - Income Taxes - Reconciliation of Income Tax (Details) Network

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738 Statement Table [Table] Table

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739 Legal Entity [Axis] Axis dei:LegalEntityAxis
740 Entity [Domain] Member dei:EntityDomain
741 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
742 Loss before income taxes Concept (Monetary) For Period Credit ifrs-full:AccountingProfit
743 Statutory income tax rate Concept (Percent) For Period ifrs-full:ApplicableTaxRate
744 Computed income tax recovery Concept (Monetary) For Period Debit ifrs-full:TaxExpenseIncomeAtApplicableTaxRate
745 Unrecorded potential tax benefits Concept (Monetary) For Period Debit cmta:TaxEffectOfUnrecordedPotentialTaxBenefits
746 Decrease in deferred tax assets resulting from a reduction in tax rate Concept (Monetary) For Period Debit ifrs-full:TaxEffectFromChangeInTaxRate
747 Income taxable at a different foreign tax rate Concept (Monetary) For Period Debit ifrs-full:TaxEffectOfForeignTaxRates
748 Accounting charges not deducted for tax and other Concept (Monetary) For Period Debit ifrs-full:TaxEffectOfExpenseNotDeductibleInDeterminingTaxableProfitTaxLoss
749 Current income tax expense Concept (Monetary) For Period Debit ifrs-full:IncomeTaxExpenseContinuingOperations
750 053 - Disclosure - Note 11 - Income Taxes - Changes in Deferred Tax Liabilities (Asset) (Details) Network

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751 Statement Table [Table] Table

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752 Temporary difference, unused tax losses and unused tax credits [axis] Axis ifrs-full:TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis
753 Temporary difference, unused tax losses and unused tax credits [member] Member ifrs-full:TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsMember
754 Unused tax losses [member] Member ifrs-full:UnusedTaxLossesMember
755 Unused research and development expenditures [member] Member cmta:UnusedResearchAndDevelopmentExpendituresMember
756 Financing costs [member] Member cmta:FinancingCostsMember
757 Costs relating to patents and others [member] Member cmta:CostsRelatingToPatentsAndOthersMember
758 Property and equipment [member] Member cmta:PropertyAndEquipmentMember
759 Legal Entity [Axis] Axis dei:LegalEntityAxis
760 Entity [Domain] Member dei:EntityDomain
761 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
762 Deferred tax assets Concept (Monetary) As Of Debit ifrs-full:DeferredTaxAssets
763 Deferred tax liabilities Concept (Monetary) As Of Credit ifrs-full:DeferredTaxLiabilities
764 Deferred tax liability (asset) Concept (Monetary) As Of Credit ifrs-full:DeferredTaxLiabilityAsset
765 Unrecorded deferred income tax assets Concept (Monetary) As Of Debit cmta:UnrecordedDeferredIncomeTaxAssets
766 054 - Disclosure - Note 11 - Income Taxes - Loss Carryforwards, Unclaimed Deductions and Credits Available for Carryforward (Details) Network

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767 Statement Table [Table] Table

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768 Temporary difference, unused tax losses and unused tax credits [axis] Axis ifrs-full:TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis
769 Temporary difference, unused tax losses and unused tax credits [member] Member ifrs-full:TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsMember
770 Unused tax losses, expiring 2029 [member] Member cmta:UnusedTaxLossesExpiring2029Member
771 R&D Tax Credits [member] Member cmta:RDTaxCreditsMember
772 Unused tax losses, expiring 2030 [member] Member cmta:UnusedTaxLossesExpiring2030Member
773 Unused tax losses, expiring 2031 [member] Member cmta:UnusedTaxLossesExpiring2031Member
774 Unused tax losses, expiring 2032 [member] Member cmta:UnusedTaxLossesExpiring2032Member
775 Unused tax losses, expiring 2033 [member] Member cmta:UnusedTaxLossesExpiring2033Member
776 Unused tax losses, expiring 2034 [member] Member cmta:UnusedTaxLossesExpiring2034Member
777 Unused tax losses, expiring 2035 [member] Member cmta:UnusedTaxLossesExpiring2035Member
778 Unused tax losses, expiring 2036 [member] Member cmta:UnusedTaxLossesExpiring2036Member
779 Unused tax losses, expiring 2037 [member] Member cmta:UnusedTaxLossesExpiring2037Member
780 Unused tax losses, expiring 2038 [member] Member cmta:UnusedTaxLossesExpiring2038Member
781 Unused tax credits, Expiring 2033 [member] Member cmta:UnusedTaxCreditsExpiring2033Member
782 Unused tax credits, Expiring 2034 [member] Member cmta:UnusedTaxCreditsExpiring2034Member
783 Unused tax credits, Expiring 2035 [member] Member cmta:UnusedTaxCreditsExpiring2035Member
784 Unused tax credits, Expiring 2036 [member] Member cmta:UnusedTaxCreditsExpiring2036Member
785 Unused tax credits, Expiring 2037 [member] Member cmta:UnusedTaxCreditsExpiring2037Member
786 Orphan drug tax credits, Expiring 2037 [member] Member cmta:OrphanDrugTaxCreditsExpiring2037Member
787 Orphan drug tax credits, Expiring 2038 [member] Member cmta:OrphanDrugTaxCreditsExpiring2038Member
788 Orphan drug tax credits [member] Member cmta:OrphanDrugTaxCreditsMember
789 Legal Entity [Axis] Axis dei:LegalEntityAxis
790 Entity [Domain] Member dei:EntityDomain
791 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
792 Losses carried forward, provincial Concept (Monetary) As Of Debit cmta:LossCarryforwardsSubjectToVerificationByProvincialTaxAuthorities
793 Losses carried forward, federal Concept (Monetary) As Of Debit cmta:LossCarryforwardsSubjectToVerificationByFederallTaxAuthorities
794 Unused tax credits, federal Concept (Monetary) As Of Debit cmta:UnusedTaxCreditsSubjectToVerificationByFederalTaxAuthorities
795 Unused tax credits, state Concept (Monetary) As Of Debit cmta:UnusedTaxCreditsSubjectToVerificationByStateTaxAuthorities
796 055 - Disclosure - Note 12 - Additional Information on the Consolidated Statements of Net Loss and Comprehensive Loss - Net Loss and Comprehensive Loss (Details) Network

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797 Statement Table [Table] Table

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798 Legal Entity [Axis] Axis dei:LegalEntityAxis
799 Entity [Domain] Member dei:EntityDomain
800 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
801 Employee benefits expense, included in research and development expenses Concept (Monetary) For Period Debit cmta:EmployeeBenefitsExpenseIncludedInResearchAndDevelopmentExpenses
802 Depreciation of property and equipment, included in research and development expenses Concept (Monetary) For Period Debit cmta:DepreciationOfPropertyAndEquipmentIncludedInResearchAndDevelopmentExpenses
803 Rent expense, included in research and development expenses Concept (Monetary) For Period Debit cmta:ExpensesRelatedToMinimumOperatingLeasePaymentsIncludedInResearchAndDevelopmentExpenses
804 Employee benefits expense, included in general and administrative expenses Concept (Monetary) For Period Debit cmta:EmployeeBenefitsExpenseIncludedInGeneralAndAdministrativeExpenses
805 Depreciation of property and equipment, included in general and administrative expenses Concept (Monetary) For Period Debit cmta:DepreciationOfPropertyAndEquipmentIncludedInGeneralAndAdministrativeExpenses
806 Amortization of intangible assets, included in general and administrative expenses Concept (Monetary) For Period Debit cmta:AmortizationOfIntangibleAssetsIncludedInGeneralAndAdministrativeExpenses
807 Rent expense, included in general and administrative expenses Concept (Monetary) For Period Debit cmta:ExpensesRelatedToMinimumOperatingLeasePaymentsIncludedInGeneralAndAdministrativeExpenses
808 056 - Disclosure - Note 13 - Financial Expenses - Financial Expenses (Details) Network

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809 Statement Table [Table] Table

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810 Legal Entity [Axis] Axis dei:LegalEntityAxis
811 Entity [Domain] Member dei:EntityDomain
812 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
813 Transaction costs – embedded derivatives Concept (Monetary) For Period Debit ifrs-full:AdjustmentsForFinanceCosts
814 Accretion of preferred shares Concept (Monetary) For Period Debit cmta:AdjustmentForAccretionOfPreferredShares
815 Loss on re-measurement at fair value – embedded derivatives Concept (Monetary) For Period ifrs-full:GainsLossesRecognisedInProfitOrLossFairValueMeasurementLiabilities
816 Bank charges and other interest Concept (Monetary) For Period Debit cmta:BankChargesAndOtherInterest
817 Foreign exchange losses (gains) Concept (Monetary) For Period Credit ifrs-full:GainsLossesOnExchangeDifferencesOnTranslationRecognisedInProfitOrLoss
818 Total financial expenses Concept (Monetary) For Period Debit cmta:FinancialExpenses
819 057 - Disclosure - Note 14 - Commitments and Contingencies (Details Textual) Network

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820 Statement Table [Table] Table

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821 Arrangements involving legal form of lease [axis] Axis ifrs-full:ArrangementsInvolvingLegalFormOfLeaseAxis
822 Arrangements involving legal form of lease [member] Member ifrs-full:ArrangementsInvolvingLegalFormOfLeaseMember
823 Head office lease in Montreal, Quebec, Canada [member] Member cmta:HeadOfficeLeaseInMontrealQuebecCanadaMember
824 Office space in Newton Massachusetts [member] Member cmta:OfficeSpaceInNewtonMassachusettsMember
825 Non-adjusting events after reporting period [axis] Axis ifrs-full:NonadjustingEventsAfterReportingPeriodAxis
826 Non-adjusting events after reporting period [member] Member ifrs-full:NonadjustingEventsMember
827 Entering into significant commitments or contingent liabilities [member] Member ifrs-full:EnteringIntoSignificantCommitmentsOrContingentLiabilitiesMember
828 Counterparties [axis] Axis ifrs-full:CounterpartiesAxis
829 Counterparties [member] Member ifrs-full:CounterpartiesMember
830 Hoffman-La Roche [member] Member cmta:HoffmanlaRocheMember
831 Thomas Jefferson University [member] Member cmta:ThomasJeffersonUniversityMember
832 Yamaguchi University [member] Member cmta:YamaguchiUniversityMember
833 Galderma [member] Member cmta:GaldermaMember
834 Legal Entity [Axis] Axis dei:LegalEntityAxis
835 Entity [Domain] Member dei:EntityDomain
836 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
837 Lease termination fee, accrued Concept (Monetary) As Of Credit cmta:LeaseTerminationFeeAccrued
838 Lease annual payment Concept (Monetary) For Period Credit cmta:LeaseAnnualPayment
839 Lease monthly payment Concept (Monetary) For Period Credit cmta:LeaseMonthlyPayment
840 Contractual commitments for acquisition of intangible assets Concept (Monetary) As Of Credit ifrs-full:ContractualCommitmentsForAcquisitionOfIntangibleAssets
841 Accounts payable, as result of achievement of a clinical development milestone Concept (Monetary) As Of Credit cmta:AccountsPayableAsResultOfAchievementOfAClinicalDevelopmentMilestone
842 Additional contractual commitments for acquisition of intangible assets Concept (Monetary) As Of Credit cmta:AdditionalContractualCommitmentsForAcquisitionOfIntangibleAssets
843 Addition Contractual Commitments for Potential Royalties Concept (Monetary) As Of Credit cmta:AdditionContractualCommitmentsForPotentialRoyalties
844 Purchase of intangible assets Concept (Monetary) For Period Credit ifrs-full:PurchaseOfIntangibleAssetsClassifiedAsInvestingActivities
845 Contractual commitments for acquisition of intangible assets, clinical milestones Concept (Monetary) As Of Credit cmta:ContractualCommitmentsForAcquisitionOfIntangibleAssetsClinicalMilestones
846 Contractual commitments for acquisition of intangible assets, regulatory milestones Concept (Monetary) As Of Credit cmta:ContractualCommitmentsForAcquisitionOfIntangibleAssetsRegulatoryMilestones
847 Technology Access Fees Concept (Monetary) For Period Debit cmta:TechnologyAccessFees
848 058 - Disclosure - Note 14 - Commitments and Contingencies - Minimum Annual Payments of Leases (Details) Network

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849 Statement Table [Table] Table

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850 Maturity [axis] Axis ifrs-full:MaturityAxis
851 Aggregated time bands [member] Member ifrs-full:AggregatedTimeBandsMember
852 Not later than one year [member] Member ifrs-full:NotLaterThanOneYearMember
853 Later than one year and not later than two years [member] Member ifrs-full:LaterThanOneYearAndNotLaterThanTwoYearsMember
854 Later than two years and not later than three years [member] Member ifrs-full:LaterThanTwoYearsAndNotLaterThanThreeYearsMember
855 Later than three years and not later than four years [member] Member ifrs-full:LaterThanThreeYearsAndNotLaterThanFourYearsMember
856 Later than four years and not later than five years [member] Member ifrs-full:LaterThanFourYearsAndNotLaterThanFiveYearsMember
857 Later than five years [member] Member ifrs-full:LaterThanFiveYearsMember
858 Legal Entity [Axis] Axis dei:LegalEntityAxis
859 Entity [Domain] Member dei:EntityDomain
860 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
861 Lease commitments Concept (Monetary) As Of Credit ifrs-full:MinimumLeasePaymentsPayableUnderNoncancellableOperatingLease
862 Other commitments Concept (Monetary) As Of Credit cmta:OtherCommitments
863 Concept (Monetary) As Of Credit cmta:ContractualObligations
864 059 - Disclosure - Note 15 - Related Party Transactions (Details Textual) Network

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865 Statement Table [Table] Table

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866 Categories of related parties [axis] Axis ifrs-full:CategoriesOfRelatedPartiesAxis
867 Entity's total for related parties [member] Member ifrs-full:EntitysTotalForRelatedPartiesMember
868 Company controlled by an investor [member] Member cmta:CompanyControlledByAnInvestorMember
869 Key management personnel of entity or parent [member] Member ifrs-full:KeyManagementPersonnelOfEntityOrParentMember
870 Legal Entity [Axis] Axis dei:LegalEntityAxis
871 Entity [Domain] Member dei:EntityDomain
872 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
873 Amounts receivable, related party transactions Concept (Monetary) As Of Debit ifrs-full:AmountsReceivableRelatedPartyTransactions
874 Amounts payable, related party transactions Concept (Monetary) As Of Credit ifrs-full:AmountsPayableRelatedPartyTransactions
875 060 - Disclosure - Note 15 - Related Party Transactions - Compensation of Key Management Personnel (Details) Network

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876 Statement Table [Table] Table

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877 Legal Entity [Axis] Axis dei:LegalEntityAxis
878 Entity [Domain] Member dei:EntityDomain
879 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
880 Short-term benefits Concept (Monetary) For Period Debit ifrs-full:KeyManagementPersonnelCompensationShorttermEmployeeBenefits
881 Director fees Concept (Monetary) For Period Debit cmta:KeyManagementPersonnelCompensationDirectorFees
882 Concept (Monetary) For Period Debit cmta:KeyManagementPersonnelCompensationShorttermEmployeeBenefitsAndDirectFees
883 Stock-based compensation Concept (Monetary) For Period Debit ifrs-full:KeyManagementPersonnelCompensationSharebasedPayment
884 Concept (Monetary) For Period Debit ifrs-full:KeyManagementPersonnelCompensation
885 061 - Disclosure - Note 16 - Financial Instruments (Details Textual) Network

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886 Statement Table [Table] Table

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887 Legal Entity [Axis] Axis dei:LegalEntityAxis
888 Entity [Domain] Member dei:EntityDomain
889 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
890 Foreign currency risk, gain (loss) on 10% depreciation or appreciation of US dollar against the Canadian dollar Concept (Monetary) For Period Credit cmta:ForeignCurrencyRiskGainLossOn10DepreciationOrAppreciationOfUsDollarAgainstTheCanadianDollar
891 Foreign currency risk, gain (loss) on 10% depreciation or appreciation of US dollar against the Euro Concept (Monetary) For Period Credit cmta:ForeignCurrencyRiskGainLossOn10DepreciationOrAppreciationOfUsDollarAgainstTheEuro
892 062 - Disclosure - Note 16 - Financial Instruments - Exposed to Currency Risk (Details) Network

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893 Statement Table [Table] Table

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894 Legal Entity [Axis] Axis dei:LegalEntityAxis
895 Entity [Domain] Member dei:EntityDomain
896 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
897 Cash Concept (Monetary) As Of Debit ifrs-full:Cash
898 Interest, sales tax and other receivables Concept (Monetary) As Of Debit cmta:InterestSalesTaxAndOtherReceivables
899 Accounts payable and accrued liabilities Concept (Monetary) As Of Debit cmta:AccountsPayableAndAccruedLiabilities
900 Net exposure Concept (Monetary) As Of Debit cmta:NetExposure
901 063 - Disclosure - Note 16 - Financial Instruments - Exchange Rates (Details) Network

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902 Statement Table [Table] Table

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903 Currency [Axis] Axis srt:CurrencyAxis
904 All Currencies [Domain] Member currency:AllCurrenciesDomain
905 Canada, Dollars Member currency:CAD
906 Euro Member Countries, Euro Member currency:EUR
907 Legal Entity [Axis] Axis dei:LegalEntityAxis
908 Entity [Domain] Member dei:EntityDomain
909 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
910 Average rate Concept (Decimal) For Period ifrs-full:AverageForeignExchangeRate
911 Reporting date rate Concept (Decimal) As Of ifrs-full:ClosingForeignExchangeRate
912 064 - Disclosure - Note 17 - Operating Segments (Details Textual) Network

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913 Statement Table [Table] Table

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914 Legal Entity [Axis] Axis dei:LegalEntityAxis
915 Entity [Domain] Member dei:EntityDomain
916 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
917 Percentage of property and equipment located at Canada Concept (Percent) As Of cmta:PercentageOfPropertyAndEquipmentLocatedAtCanada
918 Percentage of property and equipment located at United States Concept (Percent) As Of cmta:PercentageOfPropertyAndEquipmentLocatedAtUnitedStates
919 065 - Disclosure - Note 18 - Subsequent Events (Details Textual) Network

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920 Statement Table [Table] Table

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921 Arrangements involving legal form of lease [axis] Axis ifrs-full:ArrangementsInvolvingLegalFormOfLeaseAxis
922 Arrangements involving legal form of lease [member] Member ifrs-full:ArrangementsInvolvingLegalFormOfLeaseMember
923 Head office lease in Montreal, Quebec, Canada [member] Member cmta:HeadOfficeLeaseInMontrealQuebecCanadaMember
924 Office space in Newton Massachusetts [member] Member cmta:OfficeSpaceInNewtonMassachusettsMember
925 Non-adjusting events after reporting period [axis] Axis ifrs-full:NonadjustingEventsAfterReportingPeriodAxis
926 Non-adjusting events after reporting period [member] Member ifrs-full:NonadjustingEventsMember
927 Entering into significant commitments or contingent liabilities [member] Member ifrs-full:EnteringIntoSignificantCommitmentsOrContingentLiabilitiesMember
928 Major ordinary share transactions [member] Member ifrs-full:MajorOrdinaryShareTransactionsMember
929 Agreement with Ipsen [member] Member cmta:AgreementWithIpsenMember
930 Ordinary transactions [member] Member cmta:OrdinaryTransactionsMember
931 Types of share-based payment arrangements [axis] Axis ifrs-full:TypesOfSharebasedPaymentArrangementsAxis
932 Share-based payment arrangements [member] Member ifrs-full:SharebasedPaymentArrangementsMember
933 Deferred share units (DSUs) [member] Member cmta:DeferredShareUnitsDsusMember
934 Legal Entity [Axis] Axis dei:LegalEntityAxis
935 Entity [Domain] Member dei:EntityDomain
936 Statement Line Items [Line Items] LineItems cmta:StatementLineItems
937 Lease termination fee, accrued Concept (Monetary) As Of Credit cmta:LeaseTerminationFeeAccrued
938 Lease annual payment Concept (Monetary) For Period Credit cmta:LeaseAnnualPayment
939 Number of share options granted in share-based payment arrangement Concept (Decimal) For Period ifrs-full:NumberOfShareOptionsGrantedInSharebasedPaymentArrangement
940 Lease monthly payment Concept (Monetary) For Period Credit cmta:LeaseMonthlyPayment
941 Weighted average exercise price of share options granted in share-based payment arrangement Concept (Monetary) For Period ifrs-full:WeightedAverageExercisePriceOfShareOptionsGrantedInSharebasedPaymentArrangement
942 Plan of arrangement, purchase price Concept (Share) As Of cmta:PlanOfArrangementPurchasePrice
943 Plan of arrangement, contingent value right Concept (Share) As Of cmta:PlanOfArrangementContingentValueRight
944 Plan of arrangement, maximum transaction value Concept (Monetary) As Of Credit cmta:PlanOfArrangementMaximumTransactionValue
945 Plan of arrangement, termination fee payable in special circumstances Concept (Monetary) As Of Credit cmta:PlanOfArrangementTerminationFeePayableInSpecialCircumstances
946 Plan of arrangement, estimated fess and costs Concept (Monetary) For Period Debit cmta:PlanOfArrangementEstimatedFessAndCosts
947 Number of shares authorised Concept (Shares) As Of ifrs-full:NumberOfSharesAuthorised
948 Payments for lease termination fee Concept (Monetary) For Period Credit cmta:PaymentsForLeaseTerminationFee

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