<?xml version='1.0' encoding='UTF-8'?>
<FilingSummary>
  <Version>3.7.0.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>291</ContextCount>
  <ElementCount>292</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>74</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>5</UnitCount>
  <MyReports>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>00090 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>00100 - Statement - CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/StatementConsolidatedBalanceSheets</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>00105 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/StatementConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>00200 - Statement - CONSOLIDATED STATEMENTS OF OPERATIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/StatementConsolidatedStatementsOfOperations</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF OPERATIONS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>00300 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/StatementConsolidatedStatementsOfChangesInStockholdersEquity</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>00400 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/StatementConsolidatedStatementsOfCashFlows</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>10101 - Disclosure - Summary of Business and Financial Statement Presentation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureSummaryOfBusinessAndFinancialStatementPresentation</Role>
      <ShortName>Summary of Business and Financial Statement Presentation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>10201 - Disclosure - Mortgage Loans Held-for-Sale</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureMortgageLoansHeldForSale</Role>
      <ShortName>Mortgage Loans Held-for-Sale</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>10301 - Disclosure - Mortgage Servicing Rights</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureMortgageServicingRights</Role>
      <ShortName>Mortgage Servicing Rights</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>10401 - Disclosure - Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureDebt</Role>
      <ShortName>Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>10501 - Disclosure - Securitized Mortgage Trusts</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureSecuritizedMortgageTrusts</Role>
      <ShortName>Securitized Mortgage Trusts</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>10601 - Disclosure - Fair Value of Financial Instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureFairValueOfFinancialInstruments</Role>
      <ShortName>Fair Value of Financial Instruments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>10701 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureIncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>10801 - Disclosure - Reconciliation of Earnings Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureReconciliationOfEarningsPerShare</Role>
      <ShortName>Reconciliation of Earnings Per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>10901 - Disclosure - Segment Reporting</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureSegmentReporting</Role>
      <ShortName>Segment Reporting</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>11001 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>11101 - Disclosure - Equity and Share Based Payments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureEquityAndShareBasedPayments</Role>
      <ShortName>Equity and Share Based Payments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>12101 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureSubsequentEvents</Role>
      <ShortName>Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>20102 - Disclosure - Summary of Business and Financial Statement Presentation (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureSummaryOfBusinessAndFinancialStatementPresentationPolicies</Role>
      <ShortName>Summary of Business and Financial Statement Presentation (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>30203 - Disclosure - Mortgage Loans Held-for-Sale (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureMortgageLoansHeldForSaleTables</Role>
      <ShortName>Mortgage Loans Held-for-Sale (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.impaccompanies.com/role/DisclosureMortgageLoansHeldForSale</ParentRole>
      <Position>20</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>30303 - Disclosure - Mortgage Servicing Rights (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureMortgageServicingRightsTables</Role>
      <ShortName>Mortgage Servicing Rights (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.impaccompanies.com/role/DisclosureMortgageServicingRights</ParentRole>
      <Position>21</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>30403 - Disclosure - Debt (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureDebtTables</Role>
      <ShortName>Debt (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.impaccompanies.com/role/DisclosureDebt</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>30503 - Disclosure - Securitized Mortgage Trusts (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureSecuritizedMortgageTrustsTables</Role>
      <ShortName>Securitized Mortgage Trusts (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.impaccompanies.com/role/DisclosureSecuritizedMortgageTrusts</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>30603 - Disclosure - Fair Value of Financial Instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureFairValueOfFinancialInstrumentsTables</Role>
      <ShortName>Fair Value of Financial Instruments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.impaccompanies.com/role/DisclosureFairValueOfFinancialInstruments</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>30803 - Disclosure - Reconciliation of Earnings Per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureReconciliationOfEarningsPerShareTables</Role>
      <ShortName>Reconciliation of Earnings Per Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.impaccompanies.com/role/DisclosureReconciliationOfEarningsPerShare</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>30903 - Disclosure - Segment Reporting (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureSegmentReportingTables</Role>
      <ShortName>Segment Reporting (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.impaccompanies.com/role/DisclosureSegmentReporting</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>31003 - Disclosure - Commitments and Contingencies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureCommitmentsAndContingenciesTables</Role>
      <ShortName>Commitments and Contingencies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.impaccompanies.com/role/DisclosureCommitmentsAndContingencies</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>31103 - Disclosure - Equity and Share Based Payments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureEquityAndShareBasedPaymentsTables</Role>
      <ShortName>Equity and Share Based Payments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.impaccompanies.com/role/DisclosureEquityAndShareBasedPayments</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>40201 - Disclosure - Mortgage Loans Held-for-Sale (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureMortgageLoansHeldForSaleDetails</Role>
      <ShortName>Mortgage Loans Held-for-Sale (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.impaccompanies.com/role/DisclosureMortgageLoansHeldForSaleTables</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>40301 - Disclosure - Mortgage Servicing Rights (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureMortgageServicingRightsDetails</Role>
      <ShortName>Mortgage Servicing Rights (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.impaccompanies.com/role/DisclosureMortgageServicingRightsTables</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>40401 - Disclosure - Debt - Warehouse Borrowings (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureDebtWarehouseBorrowingsDetails</Role>
      <ShortName>Debt - Warehouse Borrowings (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>40403 - Disclosure - Debt - Term Financing (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureDebtTermFinancingDetails</Role>
      <ShortName>Debt - Term Financing (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>40404 - Disclosure - Debt - Convertible Notes (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureDebtConvertibleNotesDetails</Role>
      <ShortName>Debt - Convertible Notes (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>40501 - Disclosure - Securitized Mortgage Trusts- Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureSecuritizedMortgageTrustsAssetsDetails</Role>
      <ShortName>Securitized Mortgage Trusts- Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>40502 - Disclosure - Securitized Mortgage Trusts - Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureSecuritizedMortgageTrustsLiabilitiesDetails</Role>
      <ShortName>Securitized Mortgage Trusts - Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>40505 - Disclosure - Securitized Mortgage Trusts - Change in Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureSecuritizedMortgageTrustsChangeInFairValueDetails</Role>
      <ShortName>Securitized Mortgage Trusts - Change in Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>40601 - Disclosure - Fair Value of Financial Instruments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureFairValueOfFinancialInstrumentsDetailss</Role>
      <ShortName>Fair Value of Financial Instruments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.impaccompanies.com/role/DisclosureFairValueOfFinancialInstrumentsTables</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>40602 - Disclosure - Fair Value of Financial Instruments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureFairValueOfFinancialInstrumentsDetails</Role>
      <ShortName>Fair Value of Financial Instruments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.impaccompanies.com/role/DisclosureFairValueOfFinancialInstrumentsTables</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>40603 - Disclosure - Fair Value of Financial Instruments - Reconciliations for Assets and Liabilities Measured Using Level 3 (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureFairValueOfFinancialInstrumentsReconciliationsForAssetsAndLiabilitiesMeasuredUsingLevel3Details</Role>
      <ShortName>Fair Value of Financial Instruments - Reconciliations for Assets and Liabilities Measured Using Level 3 (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>40604 - Disclosure - Fair Value of Financial Instruments - Valuation Techniques And Unobservable Inputs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureFairValueOfFinancialInstrumentsValuationTechniquesAndUnobservableInputsDetails</Role>
      <ShortName>Fair Value of Financial Instruments - Valuation Techniques And Unobservable Inputs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>40605 - Disclosure - Fair Value of Financial Instruments - Changes in Fair Value Included in Earnings (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureFairValueOfFinancialInstrumentsChangesInFairValueIncludedInEarningsDetails</Role>
      <ShortName>Fair Value of Financial Instruments - Changes in Fair Value Included in Earnings (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>40606 - Disclosure - Fair Value of Financial Instruments - Nonrecurring (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureFairValueOfFinancialInstrumentsNonrecurringDetails</Role>
      <ShortName>Fair Value of Financial Instruments - Nonrecurring (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>40701 - Disclosure - Income Taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureIncomeTaxesDetails</Role>
      <ShortName>Income Taxes (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.impaccompanies.com/role/DisclosureIncomeTaxes</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>40801 - Disclosure - Reconciliation of Earnings Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureReconciliationOfEarningsPerShareDetails</Role>
      <ShortName>Reconciliation of Earnings Per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.impaccompanies.com/role/DisclosureReconciliationOfEarningsPerShareTables</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>40901 - Disclosure - Segment Reporting - Statement of Operations Items (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureSegmentReportingStatementOfOperationsItemsDetails</Role>
      <ShortName>Segment Reporting - Statement of Operations Items (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>40902 - Disclosure - Segment Reporting - Balance Sheet Items (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureSegmentReportingBalanceSheetItemsDetails</Role>
      <ShortName>Segment Reporting - Balance Sheet Items (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>41001 - Disclosure - Commitments and Contingencies - Loan Commitments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureCommitmentsAndContingenciesLoanCommitmentsDetails</Role>
      <ShortName>Commitments and Contingencies - Loan Commitments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>41002 - Disclosure - Commitments and Contingencies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureCommitmentsAndContingenciesDetails</Role>
      <ShortName>Commitments and Contingencies (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.impaccompanies.com/role/DisclosureCommitmentsAndContingenciesTables</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>41101 - Disclosure - Equity and Share Based Payments - Equity Offering Program (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureEquityAndShareBasedPaymentsEquityOfferingProgramDetails</Role>
      <ShortName>Equity and Share Based Payments - Equity Offering Program (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>41102 - Disclosure - Equity and Share Based Payments - Stock Options (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureEquityAndShareBasedPaymentsStockOptionsDetails</Role>
      <ShortName>Equity and Share Based Payments - Stock Options (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>41103 - Disclosure - Share Based Payments and Employee Benefit Plans - Deferred Stock Units (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureShareBasedPaymentsAndEmployeeBenefitPlansDeferredStockUnitsDetails</Role>
      <ShortName>Share Based Payments and Employee Benefit Plans - Deferred Stock Units (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="imh-20170331.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>41201 - Disclosure - Subsequent Events (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.impaccompanies.com/role/DisclosureSubsequentEventsDetails</Role>
      <ShortName>Subsequent Events (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.impaccompanies.com/role/DisclosureSubsequentEvents</ParentRole>
      <Position>52</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>imh-20170331.xml</File>
    <File>imh-20170331.xsd</File>
    <File>imh-20170331_cal.xml</File>
    <File>imh-20170331_def.xml</File>
    <File>imh-20170331_lab.xml</File>
    <File>imh-20170331_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies/>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
