<?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>2.4.1.9</Version>
  <ProcessingTime />
  <ReportFormat>Html</ReportFormat>
  <ContextCount>99</ContextCount>
  <ElementCount>156</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>40</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>14</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0001000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/DocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>1001000 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/ConsolidatedBalanceSheets</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>1002000 - Statement - Consolidated Statements of Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/ConsolidatedStatementsOfIncome</Role>
      <ShortName>Consolidated Statements of Income</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>1003000 - Statement - Consolidated Statements of Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/ConsolidatedStatementsOfComprehensiveIncome</Role>
      <ShortName>Consolidated Statements of Comprehensive Income</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>1004000 - Statement - Consolidated Statements of Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/ConsolidatedStatementsOfStockholdersEquity</Role>
      <ShortName>Consolidated Statements of Stockholders' Equity</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>1005000 - Statement - Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/ConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>2101100 - Disclosure - NATURE OF BUSINESS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/NatureOfBusiness</Role>
      <ShortName>NATURE OF BUSINESS</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>2103100 - Disclosure - BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/BasisOfPresentationAndSummaryOfSignificantAccountingPolicies</Role>
      <ShortName>BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>2104100 - Disclosure - INVENTORIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/Inventories</Role>
      <ShortName>INVENTORIES</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>2106100 - Disclosure - LONG-TERM DEBT / INTEREST EXPENSE</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/LongTermDebtInterestExpense</Role>
      <ShortName>LONG-TERM DEBT / INTEREST EXPENSE</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>2107100 - Disclosure - FINANCIAL INSTRUMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/FinancialInstruments</Role>
      <ShortName>FINANCIAL INSTRUMENTS</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>2108100 - Disclosure - CONTINGENCIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/Contingencies</Role>
      <ShortName>CONTINGENCIES</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>2109100 - Disclosure - STOCK-BASED COMPENSATION PLANS AND SHARE REPURCHASE PROGRAM</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/StockBasedCompensationPlansAndShareRepurchaseProgram</Role>
      <ShortName>STOCK-BASED COMPENSATION PLANS AND SHARE REPURCHASE PROGRAM</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>2110100 - Disclosure - SEGMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/Segments</Role>
      <ShortName>SEGMENTS</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>2111100 - Disclosure - INCOME TAXES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/IncomeTaxes</Role>
      <ShortName>INCOME TAXES</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>2112100 - Disclosure - SUBSEQUENT EVENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/SubsequentEvents</Role>
      <ShortName>SUBSEQUENT EVENTS</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>2203201 - Disclosure - BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/BasisOfPresentationAndSummaryOfSignificantAccountingPoliciesPolicies</Role>
      <ShortName>BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>2304301 - Disclosure - INVENTORIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/InventoriesTables</Role>
      <ShortName>INVENTORIES (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>2306301 - Disclosure - LONG-TERM DEBT / INTEREST EXPENSE (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/LongTermDebtInterestExpenseTables</Role>
      <ShortName>LONG-TERM DEBT / INTEREST EXPENSE (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>2307301 - Disclosure - FINANCIAL INSTRUMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/FinancialInstrumentsTables</Role>
      <ShortName>FINANCIAL INSTRUMENTS (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>2309301 - Disclosure - STOCK-BASED COMPENSATION PLANS AND SHARE REPURCHASE PROGRAM (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/StockBasedCompensationPlansAndShareRepurchaseProgramTables</Role>
      <ShortName>STOCK-BASED COMPENSATION PLANS AND SHARE REPURCHASE PROGRAM (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>2310301 - Disclosure - SEGMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/SegmentsTables</Role>
      <ShortName>SEGMENTS (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>2401401 - Disclosure - NATURE OF BUSINESS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/NatureOfBusinessDetails</Role>
      <ShortName>NATURE OF BUSINESS (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>2403402 - Disclosure - BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/BasisOfPresentationAndSummaryOfSignificantAccountingPoliciesDetails</Role>
      <ShortName>BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>2404402 - Disclosure - INVENTORIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/InventoriesDetails</Role>
      <ShortName>INVENTORIES (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>2406402 - Disclosure - LONG-TERM DEBT / INTEREST EXPENSE (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/LongTermDebtInterestExpenseDetails</Role>
      <ShortName>LONG-TERM DEBT / INTEREST EXPENSE (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>2406403 - Disclosure - LONG-TERM DEBT / INTEREST EXPENSE (Details 2)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/LongTermDebtInterestExpenseDetails2</Role>
      <ShortName>LONG-TERM DEBT / INTEREST EXPENSE (Details 2)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>2407402 - Disclosure - FINANCIAL INSTRUMENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/FinancialInstrumentsDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>2408401 - Disclosure - CONTINGENCIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/ContingenciesDetails</Role>
      <ShortName>CONTINGENCIES (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>2409402 - Disclosure - STOCK-BASED COMPENSATION PLANS AND SHARE REPURCHASE PROGRAM (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/StockBasedCompensationPlansAndShareRepurchaseProgramDetails</Role>
      <ShortName>STOCK-BASED COMPENSATION PLANS AND SHARE REPURCHASE PROGRAM (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>2409403 - Disclosure - STOCK-BASED COMPENSATION PLANS AND SHARE REPURCHASE PROGRAM STOCK-BASED COMPENSATION PLANS AND SHARE REPURCHASE PROGRAM - SCHEDULE OF SHARE-BASED COMPENSATION AWARDS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/StockBasedCompensationPlansAndShareRepurchaseProgramStockBasedCompensationPlansAndShareRepurchaseProgramScheduleOfShareBasedCompensationAwardsDetails</Role>
      <ShortName>STOCK-BASED COMPENSATION PLANS AND SHARE REPURCHASE PROGRAM STOCK-BASED COMPENSATION PLANS AND SHARE REPURCHASE PROGRAM - SCHEDULE OF SHARE-BASED COMPENSATION AWARDS (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>2410402 - Disclosure - SEGMENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/SegmentsDetails</Role>
      <ShortName>SEGMENTS (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>2411401 - Disclosure - INCOME TAXES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/IncomeTaxesDetails</Role>
      <ShortName>INCOME TAXES (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>2412401 - Disclosure - SUBSEQUENT EVENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gnc.com/role/SubsequentEventsDetails</Role>
      <ShortName>SUBSEQUENT EVENTS (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_NetIncomeLoss had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_PaymentsForRepurchaseOfCommonStock had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">'Monetary' elements on report '2403402 - Disclosure - BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2406402 - Disclosure - LONG-TERM DEBT / INTEREST EXPENSE (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2409402 - Disclosure - STOCK-BASED COMPENSATION PLANS AND SHARE REPURCHASE PROGRAM (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2411401 - Disclosure - INCOME TAXES (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">Process Flow-Through: 1001000 - Statement - Consolidated Balance Sheets</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Mar. 31, 2014'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2013'</Log>
    <Log type="Info">Process Flow-Through: 1002000 - Statement - Consolidated Statements of Income</Log>
    <Log type="Info">Process Flow-Through: 1003000 - Statement - Consolidated Statements of Comprehensive Income</Log>
    <Log type="Info">Process Flow-Through: 1005000 - Statement - Consolidated Statements of Cash Flows</Log>
  </Logs>
  <InputFiles>
    <File>gnc-20150331.xml</File>
    <File>gnc-20150331.xsd</File>
    <File>gnc-20150331_cal.xml</File>
    <File>gnc-20150331_def.xml</File>
    <File>gnc-20150331_lab.xml</File>
    <File>gnc-20150331_pre.xml</File>
  </InputFiles>
  <SupplementalFiles />
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
