<?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>Html</ReportFormat>
  <ContextCount>617</ContextCount>
  <ElementCount>679</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>188</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>14</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>00090 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>00100 - Statement - Consolidated Statements Of Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/StatementConsolidatedStatementsOfIncome</Role>
      <ShortName>Consolidated Statements Of Income</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>00200 - Statement - Consolidated Statements Of Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/StatementConsolidatedStatementsOfComprehensiveIncome</Role>
      <ShortName>Consolidated Statements Of Comprehensive Income</ShortName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>00300 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/StatementConsolidatedBalanceSheets</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>00305 - Statement - Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/StatementConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Consolidated Balance Sheets (Parenthetical)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>00400 - Statement - Consolidated Statements Of Changes In Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/StatementConsolidatedStatementsOfChangesInStockholdersEquity</Role>
      <ShortName>Consolidated Statements Of Changes In Stockholders' Equity</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>00500 - Statement - Consolidated Statements Of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/StatementConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Consolidated Statements Of Cash Flows</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>10101 - Disclosure - Summary Of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureSummaryOfSignificantAccountingPolicies</Role>
      <ShortName>Summary Of Significant Accounting Policies</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>10201 - Disclosure - Acquisitions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureAcquisitions</Role>
      <ShortName>Acquisitions</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>10301 - Disclosure - Out Of Period Adjustments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureOutOfPeriodAdjustments</Role>
      <ShortName>Out Of Period Adjustments</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>10401 - Disclosure - Property, Plant &amp; Equipment</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosurePropertyPlantEquipment</Role>
      <ShortName>Property, Plant &amp; Equipment</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>10501 - Disclosure - Gain On Sale Of Other Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureGainOnSaleOfOtherAssets</Role>
      <ShortName>Gain On Sale Of Other Assets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>10601 - Disclosure - Long-Term Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureLongTermDebt</Role>
      <ShortName>Long-Term Debt</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>10701 - Disclosure - Other Long Term Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureOtherLongTermLiabilities</Role>
      <ShortName>Other Long Term Liabilities</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>10801 - Disclosure - Self-Retention Insurance</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureSelfRetentionInsurance</Role>
      <ShortName>Self-Retention Insurance</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>10901 - Disclosure - Employee Benefit Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureEmployeeBenefitPlans</Role>
      <ShortName>Employee Benefit Plans</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>11001 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureIncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>11101 - Disclosure - Transactions With Related Parties</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureTransactionsWithRelatedParties</Role>
      <ShortName>Transactions With Related Parties</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>11201 - Disclosure - Commitments And Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments And Contingencies</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>11301 - Disclosure - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureLeases</Role>
      <ShortName>Leases</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>11401 - Disclosure - Deferred Charges And Intangible Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureDeferredChargesAndIntangibleAssets</Role>
      <ShortName>Deferred Charges And Intangible Assets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>11501 - Disclosure - Significant Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureSignificantOperations</Role>
      <ShortName>Significant Operations</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>11601 - Disclosure - Unconsolidated Entities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureUnconsolidatedEntities</Role>
      <ShortName>Unconsolidated Entities</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>11701 - Disclosure - Supplemental Cash Flow Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureSupplementalCashFlowInformation</Role>
      <ShortName>Supplemental Cash Flow Information</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>11801 - Disclosure - Fair Value Of Financial Instruments, Derivatives And Marketable Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureFairValueOfFinancialInstrumentsDerivativesAndMarketableSecurities</Role>
      <ShortName>Fair Value Of Financial Instruments, Derivatives And Marketable Securities</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>11901 - Disclosure - Accounts Payable And Accrued Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureAccountsPayableAndAccruedLiabilities</Role>
      <ShortName>Accounts Payable And Accrued Liabilities</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>12001 - Disclosure - Earnings Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureEarningsPerShare</Role>
      <ShortName>Earnings Per Share</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>12101 - Disclosure - Accumulated Other Comprehensive Loss</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureAccumulatedOtherComprehensiveLoss</Role>
      <ShortName>Accumulated Other Comprehensive Loss</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>12201 - Disclosure - Stock Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureStockBasedCompensation</Role>
      <ShortName>Stock Based Compensation</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>12301 - Disclosure - Stock Repurchase Program</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureStockRepurchaseProgram</Role>
      <ShortName>Stock Repurchase Program</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>12401 - Disclosure - Fair Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureFairValueMeasurements</Role>
      <ShortName>Fair Value Measurements</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>12501 - Disclosure - Impairment Of Long Lived Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureImpairmentOfLongLivedAssets</Role>
      <ShortName>Impairment Of Long Lived Assets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>12601 - Disclosure - Changes In Accounting Estimates</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureChangesInAccountingEstimates</Role>
      <ShortName>Changes In Accounting Estimates</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>12701 - Disclosure - Quarterly Financial Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureQuarterlyFinancialInformation</Role>
      <ShortName>Quarterly Financial Information</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>12801 - Disclosure - Preferred Stock</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosurePreferredStock</Role>
      <ShortName>Preferred Stock</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>12901 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureSubsequentEvents</Role>
      <ShortName>Subsequent Events</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>13001 - Disclosure - Valuation And Qualifying Accounts And Reserves</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureValuationAndQualifyingAccountsAndReserves</Role>
      <ShortName>Valuation And Qualifying Accounts And Reserves</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>20102 - Disclosure - Summary Of Significant Accounting Policies (Policy)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicy</Role>
      <ShortName>Summary Of Significant Accounting Policies (Policy)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>30103 - Disclosure - Summary Of Significant Accounting Policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureSummaryOfSignificantAccountingPoliciesTables</Role>
      <ShortName>Summary Of Significant Accounting Policies (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>30203 - Disclosure - Acquisitions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureAcquisitionsTables</Role>
      <ShortName>Acquisitions (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>30403 - Disclosure - Property, Plant &amp; Equipment (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosurePropertyPlantEquipmentTables</Role>
      <ShortName>Property, Plant &amp; Equipment (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>30603 - Disclosure - Long-Term Debt (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureLongTermDebtTables</Role>
      <ShortName>Long-Term Debt (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>30703 - Disclosure - Other Long Term Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureOtherLongTermLiabilitiesTables</Role>
      <ShortName>Other Long Term Liabilities (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>30903 - Disclosure - Employee Benefit Plans (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureEmployeeBenefitPlansTables</Role>
      <ShortName>Employee Benefit Plans (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>31003 - Disclosure - Income Taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureIncomeTaxesTables</Role>
      <ShortName>Income Taxes (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>31303 - Disclosure - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureLeasesTables</Role>
      <ShortName>Leases (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>31403 - Disclosure - Deferred Charges And Intangible Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureDeferredChargesAndIntangibleAssetsTables</Role>
      <ShortName>Deferred Charges And Intangible Assets (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>31503 - Disclosure - Significant Operations (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureSignificantOperationsTables</Role>
      <ShortName>Significant Operations (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>31603 - Disclosure - Unconsolidated Entities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureUnconsolidatedEntitiesTables</Role>
      <ShortName>Unconsolidated Entities (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>31703 - Disclosure - Supplemental Cash Flow Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureSupplementalCashFlowInformationTables</Role>
      <ShortName>Supplemental Cash Flow Information (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>31803 - Disclosure - Fair Value Of Financial Instruments, Derivatives And Marketable Securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureFairValueOfFinancialInstrumentsDerivativesAndMarketableSecuritiesTables</Role>
      <ShortName>Fair Value Of Financial Instruments, Derivatives And Marketable Securities (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>31903 - Disclosure - Accounts Payable And Accrued Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureAccountsPayableAndAccruedLiabilitiesTables</Role>
      <ShortName>Accounts Payable And Accrued Liabilities (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>32003 - Disclosure - Earnings Per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureEarningsPerShareTables</Role>
      <ShortName>Earnings Per Share (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>32103 - Disclosure - Accumulated Other Comprehensive Loss (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureAccumulatedOtherComprehensiveLossTables</Role>
      <ShortName>Accumulated Other Comprehensive Loss (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>32203 - Disclosure - Stock Based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureStockBasedCompensationTables</Role>
      <ShortName>Stock Based Compensation (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>32403 - Disclosure - Fair Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureFairValueMeasurementsTables</Role>
      <ShortName>Fair Value Measurements (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>32703 - Disclosure - Quarterly Financial Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureQuarterlyFinancialInformationTables</Role>
      <ShortName>Quarterly Financial Information (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>40101 - Disclosure - Summary Of Significant Accounting Policies (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureSummaryOfSignificantAccountingPoliciesNarrativeDetails</Role>
      <ShortName>Summary Of Significant Accounting Policies (Narrative) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>40102 - Disclosure - Summary Of Significant Accounting Policies (Inventory By Class) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureSummaryOfSignificantAccountingPoliciesInventoryByClassDetails</Role>
      <ShortName>Summary Of Significant Accounting Policies (Inventory By Class) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>40103 - Disclosure - Summary Of Significant Accounting Policies (Estimated Useful Lives Of Property And Equipment) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureSummaryOfSignificantAccountingPoliciesEstimatedUsefulLivesOfPropertyAndEquipmentDetails</Role>
      <ShortName>Summary Of Significant Accounting Policies (Estimated Useful Lives Of Property And Equipment) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>40201 - Disclosure - Acquisitions (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureAcquisitionsNarrativeDetails</Role>
      <ShortName>Acquisitions (Narrative) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>40202 - Disclosure - Acquisitions (Assets Acquired And Liabilities Assumed) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureAcquisitionsAssetsAcquiredAndLiabilitiesAssumedDetails</Role>
      <ShortName>Acquisitions (Assets Acquired And Liabilities Assumed) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>40203 - Disclosure - Acquisitions (Business Acquisition, Pro Forma Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureAcquisitionsBusinessAcquisitionProFormaInformationDetails</Role>
      <ShortName>Acquisitions (Business Acquisition, Pro Forma Information) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>40204 - Disclosure - Acquisitions (Schedule Of Step Acquisition) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureAcquisitionsScheduleOfStepAcquisitionDetails</Role>
      <ShortName>Acquisitions (Schedule Of Step Acquisition) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>40205 - Disclosure - Acquisitions (Schedule Of Purchase Bargain Gain) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureAcquisitionsScheduleOfPurchaseBargainGainDetails</Role>
      <ShortName>Acquisitions (Schedule Of Purchase Bargain Gain) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>40301 - Disclosure - Out Of Period Adjustments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureOutOfPeriodAdjustmentsDetails</Role>
      <ShortName>Out Of Period Adjustments (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>40401 - Disclosure - Property, Plant &amp; Equipment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosurePropertyPlantEquipmentDetails</Role>
      <ShortName>Property, Plant &amp; Equipment (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>40501 - Disclosure - Gain On Sale Of Other Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureGainOnSaleOfOtherAssetsDetails</Role>
      <ShortName>Gain On Sale Of Other Assets (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>40601 - Disclosure - Long-Term Debt (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureLongTermDebtNarrativeDetails</Role>
      <ShortName>Long-Term Debt (Narrative) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>40602 - Disclosure - Long-Term Debt (Schedule Of Long-Term Debt) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureLongTermDebtScheduleOfLongTermDebtDetails</Role>
      <ShortName>Long-Term Debt (Schedule Of Long-Term Debt) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>40701 - Disclosure - Other Long Term Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureOtherLongTermLiabilitiesDetails</Role>
      <ShortName>Other Long Term Liabilities (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>40801 - Disclosure - Self-Retention Insurance (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureSelfRetentionInsuranceDetails</Role>
      <ShortName>Self-Retention Insurance (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>40901 - Disclosure - Employee Benefit Plans (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureEmployeeBenefitPlansNarrativeDetails</Role>
      <ShortName>Employee Benefit Plans (Narrative) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>40902 - Disclosure - Employee Benefit Plans (Assets Measured At Fair Value On A Recurring Basis) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureEmployeeBenefitPlansAssetsMeasuredAtFairValueOnRecurringBasisDetails</Role>
      <ShortName>Employee Benefit Plans (Assets Measured At Fair Value On A Recurring Basis) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>40903 - Disclosure - Employee Benefit Plans (Changes In Benefit Obligations And Fair Value Of Assets) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureEmployeeBenefitPlansChangesInBenefitObligationsAndFairValueOfAssetsDetails</Role>
      <ShortName>Employee Benefit Plans (Changes In Benefit Obligations And Fair Value Of Assets) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>40904 - Disclosure - Employee Benefit Plans (Amounts Recognized In Accumulated Other Comprehensive Income (Loss)) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureEmployeeBenefitPlansAmountsRecognizedInAccumulatedOtherComprehensiveIncomeLossDetails</Role>
      <ShortName>Employee Benefit Plans (Amounts Recognized In Accumulated Other Comprehensive Income (Loss)) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>40905 - Disclosure - Employee Benefit Plans (Components Of Net Periodic Benefit Cost) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureEmployeeBenefitPlansComponentsOfNetPeriodicBenefitCostDetails</Role>
      <ShortName>Employee Benefit Plans (Components Of Net Periodic Benefit Cost) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>40906 - Disclosure - Employee Benefit Plans (One Percent Change In Assumed Health Care Cost Trend Rates) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureEmployeeBenefitPlansOnePercentChangeInAssumedHealthCareCostTrendRatesDetails</Role>
      <ShortName>Employee Benefit Plans (One Percent Change In Assumed Health Care Cost Trend Rates) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>40907 - Disclosure - Employee Benefit Plans (Expected Future Benefit Payments) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureEmployeeBenefitPlansExpectedFutureBenefitPaymentsDetails</Role>
      <ShortName>Employee Benefit Plans (Expected Future Benefit Payments) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>40908 - Disclosure - Employee Benefit Plans (Multi-Employer Pension And Other Postretirement Benefit Plans) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureEmployeeBenefitPlansMultiEmployerPensionAndOtherPostretirementBenefitPlansDetails</Role>
      <ShortName>Employee Benefit Plans (Multi-Employer Pension And Other Postretirement Benefit Plans) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>41001 - Disclosure - Income Taxes (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureIncomeTaxesNarrativeDetails</Role>
      <ShortName>Income Taxes (Narrative) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>41002 - Disclosure - Income Taxes (Components Of Net Deferred Tax (Liability) Asset) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureIncomeTaxesComponentsOfNetDeferredTaxLiabilityAssetDetails</Role>
      <ShortName>Income Taxes (Components Of Net Deferred Tax (Liability) Asset) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>41003 - Disclosure - Income Taxes (Components Of Income Tax Provision (Benefit)) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureIncomeTaxesComponentsOfIncomeTaxProvisionBenefitDetails</Role>
      <ShortName>Income Taxes (Components Of Income Tax Provision (Benefit)) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>41004 - Disclosure - Income Taxes (Reconciliation Of U.S. Statutory Tax Rate) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureIncomeTaxesReconciliationOfUSStatutoryTaxRateDetails</Role>
      <ShortName>Income Taxes (Reconciliation Of U.S. Statutory Tax Rate) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>41005 - Disclosure - Income Taxes (Unrecognized Tax Benefits) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureIncomeTaxesUnrecognizedTaxBenefitsDetails</Role>
      <ShortName>Income Taxes (Unrecognized Tax Benefits) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>41101 - Disclosure - Transactions With Related Parties (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureTransactionsWithRelatedPartiesDetails</Role>
      <ShortName>Transactions With Related Parties (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>41201 - Disclosure - Commitments And Contingencies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureCommitmentsAndContingenciesDetails</Role>
      <ShortName>Commitments And Contingencies (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>41301 - Disclosure - Leases (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureLeasesNarrativeDetails</Role>
      <ShortName>Leases (Narrative) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>41302 - Disclosure - Leases (Future Minimum Rental Payments For Operating Leases) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureLeasesFutureMinimumRentalPaymentsForOperatingLeasesDetails</Role>
      <ShortName>Leases (Future Minimum Rental Payments For Operating Leases) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>41401 - Disclosure - Deferred Charges And Intangible Assets (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureDeferredChargesAndIntangibleAssetsNarrativeDetails</Role>
      <ShortName>Deferred Charges And Intangible Assets (Narrative) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>41402 - Disclosure - Deferred Charges And Intangible Assets (Deferred Charges And Intangible Assets) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureDeferredChargesAndIntangibleAssetsDeferredChargesAndIntangibleAssetsDetails</Role>
      <ShortName>Deferred Charges And Intangible Assets (Deferred Charges And Intangible Assets) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>41501 - Disclosure - Significant Operations (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureSignificantOperationsNarrativeDetails</Role>
      <ShortName>Significant Operations (Narrative) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>41502 - Disclosure - Significant Operations (Revenues Attributable To Major Geographic Areas) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureSignificantOperationsRevenuesAttributableToMajorGeographicAreasDetails</Role>
      <ShortName>Significant Operations (Revenues Attributable To Major Geographic Areas) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>41503 - Disclosure - Significant Operations (Segment Reporting Information By Segment) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureSignificantOperationsSegmentReportingInformationBySegmentDetails</Role>
      <ShortName>Significant Operations (Segment Reporting Information By Segment) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>41504 - Disclosure - Significant Operations (Reconciliation From Segment Totals To Consolidated) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureSignificantOperationsReconciliationFromSegmentTotalsToConsolidatedDetails</Role>
      <ShortName>Significant Operations (Reconciliation From Segment Totals To Consolidated) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R96.htm</HtmlFileName>
      <LongName>41601 - Disclosure - Unconsolidated Entities (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureUnconsolidatedEntitiesNarrativeDetails</Role>
      <ShortName>Unconsolidated Entities (Narrative) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R97.htm</HtmlFileName>
      <LongName>41602 - Disclosure - Unconsolidated Entities (Summarized Equity In Net Income Of Unconsolidated Entities) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureUnconsolidatedEntitiesSummarizedEquityInNetIncomeOfUnconsolidatedEntitiesDetails</Role>
      <ShortName>Unconsolidated Entities (Summarized Equity In Net Income Of Unconsolidated Entities) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R98.htm</HtmlFileName>
      <LongName>41701 - Disclosure - Supplemental Cash Flow Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureSupplementalCashFlowInformationDetails</Role>
      <ShortName>Supplemental Cash Flow Information (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R99.htm</HtmlFileName>
      <LongName>41801 - Disclosure - Fair Value Of Financial Instruments, Derivative And Marketable Securities (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureFairValueOfFinancialInstrumentsDerivativeAndMarketableSecuritiesNarrativeDetails</Role>
      <ShortName>Fair Value Of Financial Instruments, Derivative And Marketable Securities (Narrative) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R100.htm</HtmlFileName>
      <LongName>41802 - Disclosure - Fair Value Of Financial Instruments, Derivative And Marketable Securities (Notional And Fair Value Of Derivative Instruments) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureFairValueOfFinancialInstrumentsDerivativeAndMarketableSecuritiesNotionalAndFairValueOfDerivativeInstrumentsDetails</Role>
      <ShortName>Fair Value Of Financial Instruments, Derivative And Marketable Securities (Notional And Fair Value Of Derivative Instruments) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R101.htm</HtmlFileName>
      <LongName>41803 - Disclosure - Fair Value Of Financial Instruments, Derivative And Marketable Securities (Derivative Instruments, Effect On Other Comprehensive Income (Loss)) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureFairValueOfFinancialInstrumentsDerivativeAndMarketableSecuritiesDerivativeInstrumentsEffectOnOtherComprehensiveIncomeLossDetails</Role>
      <ShortName>Fair Value Of Financial Instruments, Derivative And Marketable Securities (Derivative Instruments, Effect On Other Comprehensive Income (Loss)) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R102.htm</HtmlFileName>
      <LongName>41804 - Disclosure - Fair Value Of Financial Instruments, Derivative And Marketable Securities (Interest Rate Derivatives) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureFairValueOfFinancialInstrumentsDerivativeAndMarketableSecuritiesInterestRateDerivativesDetails</Role>
      <ShortName>Fair Value Of Financial Instruments, Derivative And Marketable Securities (Interest Rate Derivatives) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R103.htm</HtmlFileName>
      <LongName>41805 - Disclosure - Fair Value Of Financial Instruments, Derivative And Marketable Securities (Notional Amount Of Foreign Exchange Contracts) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureFairValueOfFinancialInstrumentsDerivativeAndMarketableSecuritiesNotionalAmountOfForeignExchangeContractsDetails</Role>
      <ShortName>Fair Value Of Financial Instruments, Derivative And Marketable Securities (Notional Amount Of Foreign Exchange Contracts) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R104.htm</HtmlFileName>
      <LongName>41901 - Disclosure - Accounts Payable And Accrued Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureAccountsPayableAndAccruedLiabilitiesDetails</Role>
      <ShortName>Accounts Payable And Accrued Liabilities (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R105.htm</HtmlFileName>
      <LongName>42001 - Disclosure - Earnings Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureEarningsPerShareDetails</Role>
      <ShortName>Earnings Per Share (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R106.htm</HtmlFileName>
      <LongName>42101 - Disclosure - Accumulated Other Comprehensive Loss (Changes In Accumulated Other Comprehensive Income By Component) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureAccumulatedOtherComprehensiveLossChangesInAccumulatedOtherComprehensiveIncomeByComponentDetails</Role>
      <ShortName>Accumulated Other Comprehensive Loss (Changes In Accumulated Other Comprehensive Income By Component) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R107.htm</HtmlFileName>
      <LongName>42102 - Disclosure - Accumulated Other Comprehensive Loss (Reclassifications Out Of Accumulated Other Comprehensive Income) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureAccumulatedOtherComprehensiveLossReclassificationsOutOfAccumulatedOtherComprehensiveIncomeDetails</Role>
      <ShortName>Accumulated Other Comprehensive Loss (Reclassifications Out Of Accumulated Other Comprehensive Income) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R108.htm</HtmlFileName>
      <LongName>42201 - Disclosure - Stock Based Compensation (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureStockBasedCompensationNarrativeDetails</Role>
      <ShortName>Stock Based Compensation (Narrative) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R109.htm</HtmlFileName>
      <LongName>42202 - Disclosure - Stock Based Compensation (Summary Of Activity For Stock Awards And Summary Of RSU Activity And Related Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureStockBasedCompensationSummaryOfActivityForStockAwardsAndSummaryOfRsuActivityAndRelatedInformationDetails</Role>
      <ShortName>Stock Based Compensation (Summary Of Activity For Stock Awards And Summary Of RSU Activity And Related Information) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R110.htm</HtmlFileName>
      <LongName>42203 - Disclosure - Stock Based Compensation (Schedule Of Assumptions Used) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureStockBasedCompensationScheduleOfAssumptionsUsedDetails</Role>
      <ShortName>Stock Based Compensation (Schedule Of Assumptions Used) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R111.htm</HtmlFileName>
      <LongName>42204 - Disclosure - Stock Based Compensation (Schedule Of Compensation Expense And Reductions In Earnings Per Share) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureStockBasedCompensationScheduleOfCompensationExpenseAndReductionsInEarningsPerShareDetails</Role>
      <ShortName>Stock Based Compensation (Schedule Of Compensation Expense And Reductions In Earnings Per Share) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R112.htm</HtmlFileName>
      <LongName>42301 - Disclosure - Stock Repurchase Program (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureStockRepurchaseProgramDetails</Role>
      <ShortName>Stock Repurchase Program (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R113.htm</HtmlFileName>
      <LongName>42401 - Disclosure - Fair Value Measurements (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureFairValueMeasurementsDetails</Role>
      <ShortName>Fair Value Measurements (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R114.htm</HtmlFileName>
      <LongName>42501 - Disclosure - Impairment Of Long Lived Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureImpairmentOfLongLivedAssetsDetails</Role>
      <ShortName>Impairment Of Long Lived Assets (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R115.htm</HtmlFileName>
      <LongName>42601 - Disclosure - Changes In Accounting Estimates (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureChangesInAccountingEstimatesDetails</Role>
      <ShortName>Changes In Accounting Estimates (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R116.htm</HtmlFileName>
      <LongName>42701 - Disclosure - Quarterly Financial Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureQuarterlyFinancialInformationDetails</Role>
      <ShortName>Quarterly Financial Information (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R117.htm</HtmlFileName>
      <LongName>42801 - Disclosure - Preferred Stock (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosurePreferredStockDetails</Role>
      <ShortName>Preferred Stock (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R118.htm</HtmlFileName>
      <LongName>42901 - Disclosure - Subsequent Events (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureSubsequentEventsDetails</Role>
      <ShortName>Subsequent Events (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R119.htm</HtmlFileName>
      <LongName>43001 - Disclosure - Valuation And Qualifying Accounts And Reserves (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://intship.com/role/DisclosureValuationAndQualifyingAccountsAndReservesDetails</Role>
      <ShortName>Valuation And Qualifying Accounts And Reserves (Details)</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 ish_LineOfCreditFacilityBankFees had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element ish_NegativeBalanceRelatedToInterestRateSwapInOsloBulkAs had a mix of decimals attribute values: -5 0.</Log>
    <Log type="Info">Element ish_NotesReceivableInterestRateStatedPercentage had a mix of decimals attribute values: 0 2 4.</Log>
    <Log type="Info">Element ish_OperatingLossCarryforwardsGeneratedDuringPeriod had a mix of decimals attribute values: -5 0.</Log>
    <Log type="Info">Element ish_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsCorrelationCoefficients had a mix of decimals attribute values: 3 4.</Log>
    <Log type="Info">Element ish_VesselsGross had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_AllocatedShareBasedCompensationExpense had a mix of decimals attribute values: -5 -3 0.</Log>
    <Log type="Info">Element us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax had a mix of decimals attribute values: -5 0.</Log>
    <Log type="Info">Element us-gaap_Assets had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired had a mix of decimals attribute values: 2 3.</Log>
    <Log type="Info">Element us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeRemeasurementGain had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_DebtInstrumentCarryingAmount had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations had a mix of decimals attribute values: 2 3.</Log>
    <Log type="Info">Element us-gaap_Depreciation had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_DerivativeFixedInterestRate had a mix of decimals attribute values: 4 5.</Log>
    <Log type="Info">Element us-gaap_DerivativeForwardExchangeRate1 had a mix of decimals attribute values: 2 4.</Log>
    <Log type="Info">Element us-gaap_DueFromRelatedPartiesNoncurrent had a mix of decimals attribute values: -5 -4 -3.</Log>
    <Log type="Info">Element us-gaap_EntityWideRevenueMajorCustomerAmount had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_EquityMethodInvestmentDividendsOrDistributions had a mix of decimals attribute values: -3 0.</Log>
    <Log type="Info">Element us-gaap_GainLossOnSaleOfInvestments had a mix of decimals attribute values: -3 0.</Log>
    <Log type="Info">Element us-gaap_GeneralAndAdministrativeExpense had a mix of decimals attribute values: -3 0.</Log>
    <Log type="Info">Element us-gaap_InterestRateDerivativesAtFairValueNet had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_NotionalAmountOfForeignCurrencyCashFlowHedgeDerivatives had a mix of decimals attribute values: -8 -5 0.</Log>
    <Log type="Info">Element us-gaap_NotionalAmountOfInterestRateDerivatives had a mix of decimals attribute values: -5 0.</Log>
    <Log type="Info">Element us-gaap_PaymentsToAcquireEquityMethodInvestments had a mix of decimals attribute values: -5 -3 0.</Log>
    <Log type="Info">Element us-gaap_PreferredStockDividendsPerShareDeclared had a mix of decimals attribute values: 2 3.</Log>
    <Log type="Info">Element us-gaap_ProceedsFromDivestitureOfInterestInJointVenture had a mix of decimals attribute values: -3 0.</Log>
    <Log type="Info">Element us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">'Monetary' elements on report '00500 - Statement - Consolidated Statements Of Cash Flows' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '40101 - Disclosure - Summary Of Significant Accounting Policies (Narrative) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '40201 - Disclosure - Acquisitions (Narrative) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '40401 - Disclosure - Property, Plant &amp; Equipment (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '40501 - Disclosure - Gain On Sale Of Other Assets (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '40601 - Disclosure - Long-Term Debt (Narrative) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '40602 - Disclosure - Long-Term Debt (Schedule Of Long-Term Debt) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '40901 - Disclosure - Employee Benefit Plans (Narrative) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '41001 - Disclosure - Income Taxes (Narrative) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '41101 - Disclosure - Transactions With Related Parties (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '41201 - Disclosure - Commitments And Contingencies (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '41301 - Disclosure - Leases (Narrative) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '41401 - Disclosure - Deferred Charges And Intangible Assets (Narrative) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '41801 - Disclosure - Fair Value Of Financial Instruments, Derivative And Marketable Securities (Narrative) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '41802 - Disclosure - Fair Value Of Financial Instruments, Derivative And Marketable Securities (Notional And Fair Value Of Derivative Instruments) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '42401 - Disclosure - Fair Value Measurements (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">Process Flow-Through: 00100 - Statement - Consolidated Statements Of Income</Log>
    <Log type="Info">	Process Flow-Through: Removing column '1 Months Ended
Mar. 31, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Dec. 31, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Sep. 30, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Jun. 30, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Mar. 31, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Dec. 31, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Sep. 30, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Jun. 30, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Mar. 31, 2012'</Log>
    <Log type="Info">Process Flow-Through: 00200 - Statement - Consolidated Statements Of Comprehensive Income</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Dec. 31, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Sep. 30, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Jun. 30, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Mar. 31, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Dec. 31, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Sep. 30, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Jun. 30, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Mar. 31, 2012'</Log>
    <Log type="Info">Process Flow-Through: 00300 - Statement - Consolidated Balance Sheets</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2011'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2010'</Log>
    <Log type="Info">Process Flow-Through: 00305 - Statement - Consolidated Balance Sheets (Parenthetical)</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'May 07, 2012'</Log>
    <Log type="Info">Process Flow-Through: 00500 - Statement - Consolidated Statements Of Cash Flows</Log>
  </Logs>
  <InputFiles>
    <File>ish-20131231.xml</File>
    <File>ish-20131231.xsd</File>
    <File>ish-20131231_cal.xml</File>
    <File>ish-20131231_def.xml</File>
    <File>ish-20131231_lab.xml</File>
    <File>ish-20131231_pre.xml</File>
  </InputFiles>
  <SupplementalFiles />
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
