<?xml version="1.0" encoding="utf-8"?>
<FilingSummary xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Version>2.4.0.6</Version>
  <ProcessingTime />
  <ReportFormat>Html</ReportFormat>
  <ContextCount>357</ContextCount>
  <ElementCount>546</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>105</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>10</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>0010 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/BalanceSheet</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>0015 - Statement - Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/BalanceSheetParenthetical</Role>
      <ShortName>Consolidated Balance Sheets (Parenthetical)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>0020 - Statement - Consolidated Statements of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/StatementOfIncome</Role>
      <ShortName>Consolidated Statements of Operations</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>0030 - Statement - Consolidated Statements of Comprehensive Income (Loss)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/Statement-ConsolidatedStatementsofComprehensiveIncomeLoss</Role>
      <ShortName>Consolidated Statements of Comprehensive Income (Loss)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>0040 - Statement - Consolidated Statements of Shareholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/StatementOfStockholdersEquity</Role>
      <ShortName>Consolidated Statements of Shareholders' Equity</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>0050 - Statement - Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/CashFlows</Role>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>1010 - Disclosure - Company organization and operations:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureCompanyOrganizationAndOperations</Role>
      <ShortName>Company organization and operations:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>1020 - Disclosure - Significant accounting policies:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureSignificantAccountingPolicies</Role>
      <ShortName>Significant accounting policies:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>1030 - Disclosure - Accounting changes:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureAccountingChanges</Role>
      <ShortName>Accounting changes:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>1040 - Disclosure - Business combinations:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureBusinessCombinations</Role>
      <ShortName>Business combinations:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>1050 - Disclosure - Accounts receivable:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureAccountsReceivable</Role>
      <ShortName>Accounts receivable:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>1060 - Disclosure - Inventories:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureInventories</Role>
      <ShortName>Inventories:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>1070 - Disclosure - Long-term investments:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureLongTermInvestments</Role>
      <ShortName>Long-term investments:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>1080 - Disclosure - Other assets:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureOtherAssets</Role>
      <ShortName>Other assets:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>1090 - Disclosure - Property, plant and equipment:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosurePropertyPlantAndEquipment</Role>
      <ShortName>Property, plant and equipment:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>1100 - Disclosure - Intangible assets:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureIntangibleAssets</Role>
      <ShortName>Intangible assets:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>1110 - Disclosure - Goodwill:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureGoodwill</Role>
      <ShortName>Goodwill:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>1120 - Disclosure - Accounts payable and accrued liabilities:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureAccountsPayableAndAccruedLiabilities</Role>
      <ShortName>Accounts payable and accrued liabilities:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>1130 - Disclosure - Long-term debt:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureLongTermDebt</Role>
      <ShortName>Long-term debt:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>1140 - Disclosure - Warranty liability:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureWarrantyLiability</Role>
      <ShortName>Warranty liability:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>1150 - Disclosure - Other long-term liabilities:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureOtherLongTermLiabilities</Role>
      <ShortName>Other long-term liabilities:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>1160 - Disclosure - Government assistance:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureGovernmentAssistance</Role>
      <ShortName>Government assistance:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>1170 - Disclosure - Share capital:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureShareCapital</Role>
      <ShortName>Share capital:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>1180 - Disclosure - Stock options and other stock-based plans:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureStockOptionsAndOtherStockBasedPlans</Role>
      <ShortName>Stock options and other stock-based plans:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>1190 - Disclosure - Research and development expenses:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureResearchAndDevelopmentExpenses</Role>
      <ShortName>Research and development expenses:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>1200 - Disclosure - Income taxes:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureIncomeTaxes</Role>
      <ShortName>Income taxes:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>1210 - Disclosure - Related party transactions:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureRelatedPartyTransactions</Role>
      <ShortName>Related party transactions:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>1220 - Disclosure - Service and other revenue:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureServiceAndOtherRevenue</Role>
      <ShortName>Service and other revenue:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>1230 - Disclosure - Commitments and contingencies:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments and contingencies:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>1240 - Disclosure - Segmented information:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureSegmentedInformation</Role>
      <ShortName>Segmented information:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>1250 - Disclosure - Financial instruments:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureFinancialInstruments</Role>
      <ShortName>Financial instruments:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>1260 - Disclosure - Restatement of previously issued financial statements:</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureRestatementOfPreviouslyIssuedFinancialStatements</Role>
      <ShortName>Restatement of previously issued financial statements:</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>2020 - Disclosure - Significant accounting policies: (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Significant accounting policies: (Policies)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>3020 - Disclosure - Significant accounting policies: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureSignificantAccountingPoliciesTables</Role>
      <ShortName>Significant accounting policies: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>3040 - Disclosure - Business combinations: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureBusinessCombinationsTables</Role>
      <ShortName>Business combinations: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>3050 - Disclosure - Accounts receivable: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureAccountsReceivableTables</Role>
      <ShortName>Accounts receivable: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>3060 - Disclosure - Inventories: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureInventoriesTables</Role>
      <ShortName>Inventories: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>3070 - Disclosure - Long-term investments: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureLongTermInvestmentsTables</Role>
      <ShortName>Long-term investments: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>3080 - Disclosure - Other assets: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureOtherAssetsTables</Role>
      <ShortName>Other assets: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>3090 - Disclosure - Property, plant and equipment: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosurePropertyPlantAndEquipmentTables</Role>
      <ShortName>Property, plant and equipment: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>3100 - Disclosure - Intangible assets: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureIntangibleAssetsTables</Role>
      <ShortName>Intangible assets: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>3110 - Disclosure - Goodwill: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureGoodwillTables</Role>
      <ShortName>Goodwill: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>3120 - Disclosure - Accounts payable and accrued liabilities: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureAccountsPayableAndAccruedLiabilitiesTables</Role>
      <ShortName>Accounts payable and accrued liabilities: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>3130 - Disclosure - Long-term debt: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureLongTermDebtTables</Role>
      <ShortName>Long-term debt: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>3140 - Disclosure - Warranty liability: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureWarrantyLiabilityTables</Role>
      <ShortName>Warranty liability: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>3150 - Disclosure - Other long-term liabilities: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureOtherLongTermLiabilitiesTables</Role>
      <ShortName>Other long-term liabilities: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>3180 - Disclosure - Stock options and other stock-based plans: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureStockOptionsAndOtherStockBasedPlansTables</Role>
      <ShortName>Stock options and other stock-based plans: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>3190 - Disclosure - Research and development expenses: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureResearchAndDevelopmentExpensesTables</Role>
      <ShortName>Research and development expenses: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>3200 - Disclosure - Income taxes: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureIncomeTaxesTables</Role>
      <ShortName>Income taxes: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>3210 - Disclosure - Related party transactions: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureRelatedPartyTransactionsTables</Role>
      <ShortName>Related party transactions: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>3230 - Disclosure - Commitments and contingencies: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureCommitmentsAndContingenciesTables</Role>
      <ShortName>Commitments and contingencies: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>3240 - Disclosure - Segmented information: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureSegmentedInformationTables</Role>
      <ShortName>Segmented information: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>3250 - Disclosure - Financial instruments: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureFinancialInstrumentsTables</Role>
      <ShortName>Financial instruments: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>3260 - Disclosure - Restatement of previously issued financial statements: (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureRestatementOfPreviouslyIssuedFinancialStatementsTables</Role>
      <ShortName>Restatement of previously issued financial statements: (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>4010 - Disclosure - Company organization and operations: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureCompanyOrganizationAndOperationsDetails</Role>
      <ShortName>Company organization and operations: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>4020 - Disclosure - Significant accounting policies: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureSignificantAccountingPoliciesDetails</Role>
      <ShortName>Significant accounting policies: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>4021 - Disclosure - Significant accounting policies: (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureSignificantAccountingPoliciesDetails2</Role>
      <ShortName>Significant accounting policies: (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>4040 - Disclosure - Business combinations: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureBusinessCombinationsDetails</Role>
      <ShortName>Business combinations: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>4050 - Disclosure - Accounts receivable: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureAccountsReceivableDetails</Role>
      <ShortName>Accounts receivable: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>4060 - Disclosure - Inventories: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureInventoriesDetails</Role>
      <ShortName>Inventories: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>4070 - Disclosure - Long-term investments: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureLongTermInvestmentsDetails</Role>
      <ShortName>Long-term investments: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>4071 - Disclosure - Long-term investments: (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureLongTermInvestmentsDetails2</Role>
      <ShortName>Long-term investments: (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>4072 - Disclosure - Long-term investments: (Details 3)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureLongTermInvestmentsDetails3</Role>
      <ShortName>Long-term investments: (Details 3)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>4080 - Disclosure - Other assets: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureOtherAssetsDetails</Role>
      <ShortName>Other assets: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>4090 - Disclosure - Property, plant and equipment: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosurePropertyPlantAndEquipmentDetails</Role>
      <ShortName>Property, plant and equipment: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>4100 - Disclosure - Intangible assets: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureIntangibleAssetsDetails</Role>
      <ShortName>Intangible assets: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>4110 - Disclosure - Goodwill: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureGoodwillDetails</Role>
      <ShortName>Goodwill: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>4120 - Disclosure - Accounts payable and accrued liabilities: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureAccountsPayableAndAccruedLiabilitiesDetails</Role>
      <ShortName>Accounts payable and accrued liabilities: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>4130 - Disclosure - Long-term debt: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureLongTermDebtDetails</Role>
      <ShortName>Long-term debt: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>4140 - Disclosure - Warranty liability: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureWarrantyLiabilityDetails</Role>
      <ShortName>Warranty liability: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>4150 - Disclosure - Other long-term liabilities: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureOtherLongTermLiabilitiesDetails</Role>
      <ShortName>Other long-term liabilities: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>4160 - Disclosure - Government assistance: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureGovernmentAssistanceDetails</Role>
      <ShortName>Government assistance: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>4170 - Disclosure - Share capital: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureShareCapitalDetails</Role>
      <ShortName>Share capital: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>4180 - Disclosure - Stock options and other stock-based plans: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureStockOptionsAndOtherStockBasedPlansDetails</Role>
      <ShortName>Stock options and other stock-based plans: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>4181 - Disclosure - Stock options and other stock-based plans: (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureStockOptionsAndOtherStockBasedPlansDetails2</Role>
      <ShortName>Stock options and other stock-based plans: (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>4182 - Disclosure - Stock options and other stock-based plans: (Details 3)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureStockOptionsAndOtherStockBasedPlansDetails3</Role>
      <ShortName>Stock options and other stock-based plans: (Details 3)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>4183 - Disclosure - Stock options and other stock-based plans: (Details 4)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureStockOptionsAndOtherStockBasedPlansDetails4</Role>
      <ShortName>Stock options and other stock-based plans: (Details 4)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>4184 - Disclosure - Stock options and other stock-based plans: (Details 5)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureStockOptionsAndOtherStockBasedPlansDetails5</Role>
      <ShortName>Stock options and other stock-based plans: (Details 5)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>4190 - Disclosure - Research and development expenses: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureResearchAndDevelopmentExpensesDetails</Role>
      <ShortName>Research and development expenses: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>4200 - Disclosure - Income taxes: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureIncomeTaxesDetails</Role>
      <ShortName>Income taxes: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>4201 - Disclosure - Income taxes: (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureIncomeTaxesDetails2</Role>
      <ShortName>Income taxes: (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>4202 - Disclosure - Income taxes: (Details 3)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureIncomeTaxesDetails3</Role>
      <ShortName>Income taxes: (Details 3)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>4203 - Disclosure - Income taxes: (Details 4)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureIncomeTaxesDetails4</Role>
      <ShortName>Income taxes: (Details 4)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>4210 - Disclosure - Related party transactions: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureRelatedPartyTransactionsDetails</Role>
      <ShortName>Related party transactions: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>4220 - Disclosure - Service and other revenue: (Details )</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureServiceAndOtherRevenueDetails</Role>
      <ShortName>Service and other revenue: (Details )</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>4230 - Disclosure - Commitments and contingencies: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureCommitmentsAndContingenciesDetails</Role>
      <ShortName>Commitments and contingencies: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>4240 - Disclosure - Segmented information: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureSegmentedInformationDetails</Role>
      <ShortName>Segmented information: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>4241 - Disclosure - Segmented information: (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureSegmentedInformationDetails2</Role>
      <ShortName>Segmented information: (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>4242 - Disclosure - Segmented information: (Details 3)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureSegmentedInformationDetails3</Role>
      <ShortName>Segmented information: (Details 3)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>4250 - Disclosure - Financial instruments: (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureFinancialInstrumentsDetails</Role>
      <ShortName>Financial instruments: (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>4251 - Disclosure - Financial instruments: (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureFinancialInstrumentsDetails2</Role>
      <ShortName>Financial instruments: (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>4252 - Disclosure - Financial instruments: (Details 3)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureFinancialInstrumentsDetails3</Role>
      <ShortName>Financial instruments: (Details 3)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>4253 - Disclosure - Financial instruments: (Details 4)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureFinancialInstrumentsDetails4</Role>
      <ShortName>Financial instruments: (Details 4)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>4260 - Disclosure - Restatement of previously issued financial statements (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureRestatementOfPreviouslyIssuedFinancialStatementsDetails</Role>
      <ShortName>Restatement of previously issued financial statements (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R96.htm</HtmlFileName>
      <LongName>4261 - Disclosure - Restatement of previously issued financial statements (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureRestatementOfPreviouslyIssuedFinancialStatementsDetails2</Role>
      <ShortName>Restatement of previously issued financial statements (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R97.htm</HtmlFileName>
      <LongName>4262 - Disclosure - Restatement of previously issued financial statements (Details 3)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureRestatementOfPreviouslyIssuedFinancialStatementsDetails3</Role>
      <ShortName>Restatement of previously issued financial statements (Details 3)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R98.htm</HtmlFileName>
      <LongName>4263 - Disclosure - Restatement of previously issued financial statements (Details 4)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureRestatementOfPreviouslyIssuedFinancialStatementsDetails4</Role>
      <ShortName>Restatement of previously issued financial statements (Details 4)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R99.htm</HtmlFileName>
      <LongName>4264 - Disclosure - Restatement of previously issued financial statements (Details 5)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.westport.com/role/DisclosureRestatementOfPreviouslyIssuedFinancialStatementsDetails5</Role>
      <ShortName>Restatement of previously issued financial statements (Details 5)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <Logs>
    <Log type="Info">Element us-gaap_ForeignCurrencyExchangeRateTranslation1 had a mix of decimals attribute values: 2 4.</Log>
    <Log type="Info">Element wprt_RoyaltiesToBePaidAsPercentageOfRevenue had a mix of decimals attribute values: 2 4.</Log>
    <Log type="Info">Process Flow-Through: 0010 - Statement - Consolidated Balance Sheets</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Mar. 31, 2011'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Mar. 31, 2010'</Log>
    <Log type="Info">Process Flow-Through: 0015 - Statement - Consolidated Balance Sheets (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 0020 - Statement - Consolidated Statements of Operations</Log>
    <Log type="Info">Process Flow-Through: 0030 - Statement - Consolidated Statements of Comprehensive Income (Loss)</Log>
    <Log type="Info">Process Flow-Through: 0050 - Statement - Consolidated Statements of Cash Flows</Log>
  </Logs>
  <InputFiles>
    <File>wprt-20121231.xml</File>
    <File>wprt-20121231.xsd</File>
    <File>wprt-20121231_cal.xml</File>
    <File>wprt-20121231_def.xml</File>
    <File>wprt-20121231_lab.xml</File>
    <File>wprt-20121231_pre.xml</File>
  </InputFiles>
  <SupplementalFiles />
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
