<?xml version="1.0" encoding="utf-8"?>
<FilingSummary xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <Version>2.4.0.8</Version>
  <ProcessingTime />
  <ReportFormat>HtmlAndXml</ReportFormat>
  <ContextCount>118</ContextCount>
  <ElementCount>227</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>42</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>5</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>101 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DocumentDocumentandEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <XmlFileName>R1.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>103 - Statement - Condensed Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/StatementOfFinancialPositionClassified</Role>
      <ShortName>Condensed Balance Sheets</ShortName>
      <XmlFileName>R2.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>104 - Statement - Condensed Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/StatementOfFinancialPositionClassifiedParenthetical</Role>
      <ShortName>Condensed Balance Sheets (Parenthetical)</ShortName>
      <XmlFileName>R3.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>105 - Statement - Condensed Statement of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/StatementOfIncome</Role>
      <ShortName>Condensed Statement of Operations</ShortName>
      <XmlFileName>R4.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>106 - Statement - Condensed Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/StatementOfCashFlowsIndirect</Role>
      <ShortName>Condensed Statements of Cash Flows</ShortName>
      <XmlFileName>R5.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>107 - Disclosure - Nature of Operations and Liquidity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsNatureOfOperationsAndLiquidityTextBlock</Role>
      <ShortName>Nature of Operations and Liquidity</ShortName>
      <XmlFileName>R6.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>108 - Disclosure - Basis of Presentation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock</Role>
      <ShortName>Basis of Presentation</ShortName>
      <XmlFileName>R7.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>109 - Disclosure - Reclassifications</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfReclassificationAmountTextBlock</Role>
      <ShortName>Reclassifications</ShortName>
      <XmlFileName>R8.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>110 - Disclosure - Stock-Based Compensation Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsDisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock</Role>
      <ShortName>Stock-Based Compensation Plans</ShortName>
      <XmlFileName>R9.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>111 - Disclosure - Inventories</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsInventoryDisclosureTextBlock</Role>
      <ShortName>Inventories</ShortName>
      <XmlFileName>R10.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>112 - Disclosure - Prepaid Expenses and Other Current Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsPrepaidExpensesAndOtherCurrentAssetsTextBlock</Role>
      <ShortName>Prepaid Expenses and Other Current Assets</ShortName>
      <XmlFileName>R11.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>113 - Disclosure - Fixed Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsPropertyPlantAndEquipmentDisclosureTextBlock</Role>
      <ShortName>Fixed Assets</ShortName>
      <XmlFileName>R12.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>114 - Disclosure - Accounts Payable and Accrued Expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsAccountsPayableAndAccruedLiabilitiesDisclosureTextBlock</Role>
      <ShortName>Accounts Payable and Accrued Expenses</ShortName>
      <XmlFileName>R13.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>115 - Disclosure - Notes Payable</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlock</Role>
      <ShortName>Notes Payable</ShortName>
      <XmlFileName>R14.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>116 - Disclosure - Derivative Instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsDerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock</Role>
      <ShortName>Derivative Instruments</ShortName>
      <XmlFileName>R15.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>117 - Disclosure - Net Income (Loss) Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsEarningsPerShareTextBlock</Role>
      <ShortName>Net Income (Loss) Per Share</ShortName>
      <XmlFileName>R16.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>118 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsCommitmentsAndContingenciesDisclosureTextBlock</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <XmlFileName>R17.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>119 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsIncomeTaxDisclosureTextBlock</Role>
      <ShortName>Income Taxes</ShortName>
      <XmlFileName>R18.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>120 - Disclosure - New Accounting Pronouncements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsAccountingChangesAndErrorCorrectionsTextBlock</Role>
      <ShortName>New Accounting Pronouncements</ShortName>
      <XmlFileName>R19.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>121 - Disclosure - Fair Value</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlock</Role>
      <ShortName>Fair Value</ShortName>
      <XmlFileName>R20.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>122 - Disclosure - New Accounting Pronouncements (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsAccountingChangesAndErrorCorrectionsTextBlockPolicies</Role>
      <ShortName>New Accounting Pronouncements (Policies)</ShortName>
      <XmlFileName>R21.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>123 - Disclosure - Prepaid Expenses and Other Current Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsPrepaidExpensesAndOtherCurrentAssetsTextBlockTables</Role>
      <ShortName>Prepaid Expenses and Other Current Assets (Tables)</ShortName>
      <XmlFileName>R22.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>124 - Disclosure - Fixed Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsPropertyPlantAndEquipmentDisclosureTextBlockTables</Role>
      <ShortName>Fixed Assets (Tables)</ShortName>
      <XmlFileName>R23.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>125 - Disclosure - Accounts Payable and Accrued Expenses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsAccountsPayableAndAccruedLiabilitiesDisclosureTextBlockTables</Role>
      <ShortName>Accounts Payable and Accrued Expenses (Tables)</ShortName>
      <XmlFileName>R24.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>126 - Disclosure - Notes Payable (Tables)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</Role>
      <ShortName>Notes Payable (Tables)</ShortName>
      <XmlFileName>R25.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>127 - Disclosure - Derivative Instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsDerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlockTables</Role>
      <ShortName>Derivative Instruments (Tables)</ShortName>
      <XmlFileName>R26.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>128 - Disclosure - Net Income (Loss) Per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsEarningsPerShareTextBlockTables</Role>
      <ShortName>Net Income (Loss) Per Share (Tables)</ShortName>
      <XmlFileName>R27.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>129 - Disclosure - Commitments and Contingencies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsCommitmentsAndContingenciesDisclosureTextBlockTables</Role>
      <ShortName>Commitments and Contingencies (Tables)</ShortName>
      <XmlFileName>R28.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>130 - Disclosure - Fair Value (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlockTables</Role>
      <ShortName>Fair Value (Tables)</ShortName>
      <XmlFileName>R29.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>131 - Disclosure - Nature of Operations and Liquidity - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DisclosureNatureOfOperationsAndLiquidityAdditionalInformation</Role>
      <ShortName>Nature of Operations and Liquidity - Additional Information (Detail)</ShortName>
      <XmlFileName>R30.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>132 - Disclosure - Stock-Based Compensation Plans - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DisclosureStockBasedCompensationPlansAdditionalInformation</Role>
      <ShortName>Stock-Based Compensation Plans - Additional Information (Detail)</ShortName>
      <XmlFileName>R31.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>133 - Disclosure - Prepaid Expenses and Other Current Assets - Components of Prepaid Expenses and Other Current Assets (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DisclosurePrepaidExpensesAndOtherCurrentAssetsComponentsOfPrepaidExpensesAndOtherCurrentAssets</Role>
      <ShortName>Prepaid Expenses and Other Current Assets - Components of Prepaid Expenses and Other Current Assets (Detail)</ShortName>
      <XmlFileName>R32.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>134 - Disclosure - Fixed Assets - Summary of Equipment and Leasehold Improvements (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DisclosureFixedAssetsSummaryOfEquipmentAndLeaseholdImprovements</Role>
      <ShortName>Fixed Assets - Summary of Equipment and Leasehold Improvements (Detail)</ShortName>
      <XmlFileName>R33.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>135 - Disclosure - Accounts Payable and Accrued Expenses - Summary of Accounts Payable and Accrued Expenses (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DisclosureAccountsPayableAndAccruedExpensesSummaryOfAccountsPayableAndAccruedExpenses</Role>
      <ShortName>Accounts Payable and Accrued Expenses - Summary of Accounts Payable and Accrued Expenses (Detail)</ShortName>
      <XmlFileName>R34.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>136 - Disclosure - Notes Payable - Summary of Notes Payable (Detail)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DisclosureNotesPayableSummaryOfNotesPayable</Role>
      <ShortName>Notes Payable - Summary of Notes Payable (Detail)</ShortName>
      <XmlFileName>R35.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>137 - Disclosure - Notes Payable - Additional Information (Detail)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DisclosureNotesPayableAdditionalInformation</Role>
      <ShortName>Notes Payable - Additional Information (Detail)</ShortName>
      <XmlFileName>R36.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>138 - Disclosure - Notes Payable - Statements of Fair Value Assumptions (Detail)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DisclosureNotesPayableStatementsOfFairValueAssumptions</Role>
      <ShortName>Notes Payable - Statements of Fair Value Assumptions (Detail)</ShortName>
      <XmlFileName>R37.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>139 - Disclosure - Notes Payable - Estimated Fair Value of Warrants (Detail)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DisclosureNotesPayableEstimatedFairValueOfWarrants</Role>
      <ShortName>Notes Payable - Estimated Fair Value of Warrants (Detail)</ShortName>
      <XmlFileName>R38.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>140 - Disclosure - Notes Payable - Book Value of MHR Convertible Notes (Detail)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DisclosureNotesPayableBookValueOfMHRConvertibleNotes</Role>
      <ShortName>Notes Payable - Book Value of MHR Convertible Notes (Detail)</ShortName>
      <XmlFileName>R39.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>141 - Disclosure - Derivative Instruments - Components of Derivative Instruments (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DisclosureDerivativeInstrumentsComponentsOfDerivativeInstruments</Role>
      <ShortName>Derivative Instruments - Components of Derivative Instruments (Detail)</ShortName>
      <XmlFileName>R40.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>142 - Disclosure - Derivative Instruments - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DisclosureDerivativeInstrumentsAdditionalInformation</Role>
      <ShortName>Derivative Instruments - Additional Information (Detail)</ShortName>
      <XmlFileName>R41.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>143 - Disclosure - Net Income (Loss) Per Share - Basic and Diluted Earnings Per Share (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DisclosureNetIncomeLossPerShareBasicAndDilutedEarningsPerShare</Role>
      <ShortName>Net Income (Loss) Per Share - Basic and Diluted Earnings Per Share (Detail)</ShortName>
      <XmlFileName>R42.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>144 - Disclosure - Net Income (Loss) Per Share - Potential Shares of Common Stock Excluded From Diluted Net Income Per Share (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DisclosureNetIncomeLossPerSharePotentialSharesOfCommonStockExcludedFromDilutedNetIncomePerShare</Role>
      <ShortName>Net Income (Loss) Per Share - Potential Shares of Common Stock Excluded From Diluted Net Income Per Share (Detail)</ShortName>
      <XmlFileName>R43.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>145 - Disclosure - Commitments and Contingencies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformation</Role>
      <ShortName>Commitments and Contingencies - Additional Information (Detail)</ShortName>
      <XmlFileName>R44.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>146 - Disclosure - Commitments and Contingencies - Future Minimum Rental Payments (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DisclosureCommitmentsAndContingenciesFutureMinimumRentalPayments</Role>
      <ShortName>Commitments and Contingencies - Future Minimum Rental Payments (Detail)</ShortName>
      <XmlFileName>R45.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>147 - Disclosure - Income Taxes - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DisclosureIncomeTaxesAdditionalInformation</Role>
      <ShortName>Income Taxes - Additional Information (Detail)</ShortName>
      <XmlFileName>R46.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>148 - Disclosure - Fair Value - Fair Value Hierarchy for Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DisclosureFairValueFairValueHierarchyForFinancialAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasis</Role>
      <ShortName>Fair Value - Fair Value Hierarchy for Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail)</ShortName>
      <XmlFileName>R47.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>149 - Disclosure - Fair Value - Schedule of Changes in Fair Value of Level 3 Financial Instruments (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://emisphere.com/taxonomy/role/DisclosureFairValueScheduleOfChangesInFairValueOfLevel3FinancialInstruments</Role>
      <ShortName>Fair Value - Schedule of Changes in Fair Value of Level 3 Financial Instruments (Detail)</ShortName>
      <XmlFileName>R48.xml</XmlFileName>
    </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 emis_FairValueOfEmbeddedConversionFeature had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element emis_NumberOfWarrantsSoldToFund had a mix of decimals attribute values: -5 0.</Log>
    <Log type="Info">Element emis_WarrantLiabilityFairValueDisclosure had a mix of decimals attribute values: -3 0.</Log>
    <Log type="Info">Element us-gaap_ConvertibleNotesPayable had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_DebtInstrumentFaceAmount had a mix of decimals attribute values: -6 0.</Log>
    <Log type="Info">'Monetary' elements on report '131 - Disclosure - Nature of Operations and Liquidity - Additional Information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '132 - Disclosure - Stock-Based Compensation Plans - Additional Information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '137 - Disclosure - Notes Payable - Additional Information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '142 - Disclosure - Derivative Instruments - Additional Information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '145 - Disclosure - Commitments and Contingencies - Additional Information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '147 - Disclosure - Income Taxes - Additional Information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">Process Flow-Through: 103 - Statement - Condensed Balance Sheets</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Jun. 30, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2011'</Log>
    <Log type="Info">Process Flow-Through: 104 - Statement - Condensed Balance Sheets (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 105 - Statement - Condensed Statement of Operations</Log>
    <Log type="Info">Process Flow-Through: 106 - Statement - Condensed Statements of Cash Flows</Log>
  </Logs>
  <InputFiles>
    <File>emis-20130630.xml</File>
    <File>emis-20130630.xsd</File>
    <File>emis-20130630_cal.xml</File>
    <File>emis-20130630_def.xml</File>
    <File>emis-20130630_lab.xml</File>
    <File>emis-20130630_pre.xml</File>
  </InputFiles>
  <SupplementalFiles />
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
