<?xml version="1.0" encoding="utf-8"?>
<FilingSummary xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Version>2.4.0.6</Version>
  <ProcessingTime />
  <ReportFormat>Html</ReportFormat>
  <ContextCount>269</ContextCount>
  <ElementCount>305</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>61</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>12</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0001000 - Document - Document and Entity Information Document</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/DocumentAndEntityInformationDocument</Role>
      <ShortName>Document and Entity Information Document</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>1001000 - Statement - Consolidated Statements Of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/ConsolidatedStatementsOfOperations</Role>
      <ShortName>Consolidated Statements Of Operations</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>1002000 - Statement - Consolidated Statements of Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/ConsolidatedStatementsOfComprehensiveIncome</Role>
      <ShortName>Consolidated Statements of Comprehensive Income</ShortName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>1003000 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/ConsolidatedBalanceSheets</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>1003501 - Statement - Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/ConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Consolidated Balance Sheets (Parenthetical)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>1004000 - Statement - Consolidated Statements Of Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/ConsolidatedStatementsOfStockholdersEquity</Role>
      <ShortName>Consolidated Statements Of Stockholders' Equity</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>1005000 - Statement - Consolidated Statements Of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/ConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Consolidated Statements Of Cash Flows</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>2101100 - Disclosure - Basis of Presentation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/BasisOfPresentation</Role>
      <ShortName>Basis of Presentation</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>2102100 - Disclosure - Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/SignificantAccountingPolicies</Role>
      <ShortName>Significant Accounting Policies</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>2103100 - Disclosure - Sale of Medicare PDP Business and Northeast Business</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/SaleOfMedicarePdpBusinessAndNortheastBusiness</Role>
      <ShortName>Sale of Medicare PDP Business and Northeast Business</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>2104100 - Disclosure - Segment Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/SegmentInformation</Role>
      <ShortName>Segment Information</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>2105100 - Disclosure - Investments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/Investments</Role>
      <ShortName>Investments</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>2106100 - Disclosure - Stock Repurchase Program</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/StockRepurchaseProgram</Role>
      <ShortName>Stock Repurchase Program</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>2107100 - Disclosure - Financing Arrangements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/FinancingArrangements</Role>
      <ShortName>Financing Arrangements</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>2108100 - Disclosure - Fair Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/FairValueMeasurements</Role>
      <ShortName>Fair Value Measurements</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>2109100 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/CommitmentsAndContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>2110100 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/IncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>2111100 - Disclosure - Subsequent Event</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/SubsequentEvent</Role>
      <ShortName>Subsequent Event</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>2202201 - Disclosure - Significant Accounting Policies (Policy)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/SignificantAccountingPoliciesPolicy</Role>
      <ShortName>Significant Accounting Policies (Policy)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>2302302 - Disclosure - Significant Accounting Policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/SignificantAccountingPoliciesTables</Role>
      <ShortName>Significant Accounting Policies (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>2304301 - Disclosure - Segment Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/SegmentInformationTables</Role>
      <ShortName>Segment Information (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>2305301 - Disclosure - Investments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/InvestmentsTables</Role>
      <ShortName>Investments (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>2308301 - Disclosure - Fair Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/FairValueMeasurementsTables</Role>
      <ShortName>Fair Value Measurements (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>2402403 - Disclosure - Significant Accounting Policies (Cash and Cash Equivalents, Investments and Fair Value of Financial Instruments) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/SignificantAccountingPoliciesCashAndCashEquivalentsInvestmentsAndFairValueOfFinancialInstrumentsDetails</Role>
      <ShortName>Significant Accounting Policies (Cash and Cash Equivalents, Investments and Fair Value of Financial Instruments) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>2402404 - Disclosure - Significant Accounting Policies (Health Plan Services Health Care Cost) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/SignificantAccountingPoliciesHealthPlanServicesHealthCareCostDetails</Role>
      <ShortName>Significant Accounting Policies (Health Plan Services Health Care Cost) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>2402405 - Disclosure - Significant Accounting Policies (Concentration of Credit Risk) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/SignificantAccountingPoliciesConcentrationOfCreditRiskDetails</Role>
      <ShortName>Significant Accounting Policies (Concentration of Credit Risk) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>2402406 - Disclosure - Significant Accounting Policies (Comprehensive Income) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/SignificantAccountingPoliciesComprehensiveIncomeDetails</Role>
      <ShortName>Significant Accounting Policies (Comprehensive Income) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>2402407 - Disclosure - Significant Accounting Policies (Earnings Per Share) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/SignificantAccountingPoliciesEarningsPerShareDetails</Role>
      <ShortName>Significant Accounting Policies (Earnings Per Share) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>2402408 - Disclosure - Significant Accounting Policies (Goodwill and Other Intangible Assets) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/SignificantAccountingPoliciesGoodwillAndOtherIntangibleAssetsDetails</Role>
      <ShortName>Significant Accounting Policies (Goodwill and Other Intangible Assets) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>2402409 - Disclosure - Significant Accounting Policies (Restricted Assets) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/SignificantAccountingPoliciesRestrictedAssetsDetails</Role>
      <ShortName>Significant Accounting Policies (Restricted Assets) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>2402410 - Disclosure - Significant Accounting Policies (Govenment Contracts) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/SignificantAccountingPoliciesGovenmentContractsDetails</Role>
      <ShortName>Significant Accounting Policies (Govenment Contracts) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>2403401 - Disclosure - Sale of Medicare PDP Business and Northeast Business (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/SaleOfMedicarePdpBusinessAndNortheastBusinessDetails</Role>
      <ShortName>Sale of Medicare PDP Business and Northeast Business (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>2404402 - Disclosure - Segment Information (Segment Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/SegmentInformationSegmentInformationDetails</Role>
      <ShortName>Segment Information (Segment Information) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>2404403 - Disclosure - Segment Information (Premium Revenue By Line Of Business) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/SegmentInformationPremiumRevenueByLineOfBusinessDetails</Role>
      <ShortName>Segment Information (Premium Revenue By Line Of Business) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>2405402 - Disclosure - Investments (Fair Value of Investments Available-for-Sale) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/InvestmentsFairValueOfInvestmentsAvailableForSaleDetails</Role>
      <ShortName>Investments (Fair Value of Investments Available-for-Sale) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>2405403 - Disclosure - Investments (Available-for-Sale Current Investments Classified by Contractual Maturity Date) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/InvestmentsAvailableForSaleCurrentInvestmentsClassifiedByContractualMaturityDateDetails</Role>
      <ShortName>Investments (Available-for-Sale Current Investments Classified by Contractual Maturity Date) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>2405404 - Disclosure - Investments (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/InvestmentsNarrativeDetails</Role>
      <ShortName>Investments (Narrative) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>2405405 - Disclosure - Investments (Unrealized Loss Position for Current &amp; Noncurrent Investments) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/InvestmentsUnrealizedLossPositionForCurrentNoncurrentInvestmentsDetails</Role>
      <ShortName>Investments (Unrealized Loss Position for Current &amp; Noncurrent Investments) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>2405406 - Disclosure - Investments (Number of Securities Included in Loss Position of Current and Noncurrent Investments) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/InvestmentsNumberOfSecuritiesIncludedInLossPositionOfCurrentAndNoncurrentInvestmentsDetails</Role>
      <ShortName>Investments (Number of Securities Included in Loss Position of Current and Noncurrent Investments) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>2406401 - Disclosure - Stock Repurchase Program (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/StockRepurchaseProgramDetails</Role>
      <ShortName>Stock Repurchase Program (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>2407401 - Disclosure - Financing Arrangements (Revolving Credit Facility and Letters of Credit) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/FinancingArrangementsRevolvingCreditFacilityAndLettersOfCreditDetails</Role>
      <ShortName>Financing Arrangements (Revolving Credit Facility and Letters of Credit) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>2407402 - Disclosure - Financing Arrangements (Senior Notes) (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.healthnet.com/role/FinancingArrangementsSeniorNotesDetails</Role>
      <ShortName>Financing Arrangements (Senior Notes) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>2408402 - Disclosure - Fair Value Measurements (Assets and Liabilities Measured at Fair Value) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/FairValueMeasurementsAssetsAndLiabilitiesMeasuredAtFairValueDetails</Role>
      <ShortName>Fair Value Measurements (Assets and Liabilities Measured at Fair Value) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>2408403 - Disclosure - Fair Value Measurements (Changes in the Balances of Level 3 Financial Assets) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/FairValueMeasurementsChangesInBalancesOfLevel3FinancialAssetsDetails</Role>
      <ShortName>Fair Value Measurements (Changes in the Balances of Level 3 Financial Assets) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>2408404 - Disclosure - Fair Value Measurements (Quantitative Information About Level 3 Fair Value Measurements) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/FairValueMeasurementsQuantitativeInformationAboutLevel3FairValueMeasurementsDetails</Role>
      <ShortName>Fair Value Measurements (Quantitative Information About Level 3 Fair Value Measurements) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>2409401 - Disclosure - Commitments and Contingencies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/CommitmentsAndContingenciesDetails</Role>
      <ShortName>Commitments and Contingencies (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>2410401 - Disclosure - Income Taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/IncomeTaxesDetails</Role>
      <ShortName>Income Taxes (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>2411402 - Disclosure - Subsequent Event (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.healthnet.com/role/SubsequentEventDetails</Role>
      <ShortName>Subsequent Event (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 us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_AvailableForSaleSecuritiesCurrent had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses had a mix of decimals attribute values: -5 0.</Log>
    <Log type="Info">Element us-gaap_AvailableForSaleSecuritiesNoncurrent had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_DebtInstrumentBasisSpreadOnVariableRate had a mix of decimals attribute values: 3 4.</Log>
    <Log type="Info">Element us-gaap_Goodwill had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_HealthCareOrganizationExpensesNet had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_HealthCareOrganizationPremiumRevenue had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_ProceedsFromDivestitureOfBusinesses had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_StockRepurchaseProgramAuthorizedAmount had a mix of decimals attribute values: -6 -5.</Log>
    <Log type="Info">Element us-gaap_TreasuryStockShares had a mix of decimals attribute values: -3 0.</Log>
    <Log type="Info">Element us-gaap_TreasuryStockSharesAcquired had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_TreasuryStockValueAcquiredCostMethod had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">'Shares' elements on report '1003501 - Statement - Consolidated Balance Sheets (Parenthetical)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2402406 - Disclosure - Significant Accounting Policies (Comprehensive Income) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2402408 - Disclosure - Significant Accounting Policies (Goodwill and Other Intangible Assets) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2403401 - Disclosure - Sale of Medicare PDP Business and Northeast Business (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2404402 - Disclosure - Segment Information (Segment Information) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2405402 - Disclosure - Investments (Fair Value of Investments Available-for-Sale) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2405403 - Disclosure - Investments (Available-for-Sale Current Investments Classified by Contractual Maturity Date) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2406401 - Disclosure - Stock Repurchase Program (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2407401 - Disclosure - Financing Arrangements (Revolving Credit Facility and Letters of Credit) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2407402 - Disclosure - Financing Arrangements (Senior Notes) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2408402 - Disclosure - Fair Value Measurements (Assets and Liabilities Measured at Fair Value) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2408404 - Disclosure - Fair Value Measurements (Quantitative Information About Level 3 Fair Value Measurements) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">Process Flow-Through: 1001000 - Statement - Consolidated Statements Of Operations</Log>
    <Log type="Info">	Process Flow-Through: Removing column '0 Months Ended
Apr. 02, 2012'</Log>
    <Log type="Info">Process Flow-Through: 1002000 - Statement - Consolidated Statements of Comprehensive Income</Log>
    <Log type="Info">Process Flow-Through: 1003000 - Statement - Consolidated Balance Sheets</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Jun. 30, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Sep. 30, 2011'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Jun. 30, 2011'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2010'</Log>
    <Log type="Info">Process Flow-Through: 1003501 - Statement - Consolidated Balance Sheets (Parenthetical)</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Nov. 02, 2012'</Log>
    <Log type="Info">Process Flow-Through: 1005000 - Statement - Consolidated Statements Of Cash Flows</Log>
  </Logs>
  <InputFiles>
    <File>hnt-20120930.xml</File>
    <File>hnt-20120930.xsd</File>
    <File>hnt-20120930_cal.xml</File>
    <File>hnt-20120930_def.xml</File>
    <File>hnt-20120930_lab.xml</File>
    <File>hnt-20120930_pre.xml</File>
  </InputFiles>
  <SupplementalFiles />
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
