<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.23.2</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>119</ContextCount>
  <ElementCount>213</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>22</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>4</UnitCount>
  <MyReports>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0000001 - Document - Cover</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/Cover</Role>
      <ShortName>Cover</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>0000002 - Statement - UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/UNAUDITEDCONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONSANDCOMPREHENSIVEINCOME</Role>
      <ShortName>UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>0000003 - Statement - UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/UNAUDITEDCONDENSEDCONSOLIDATEDBALANCESHEETS</Role>
      <ShortName>UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>0000004 - Statement - UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/UNAUDITEDCONDENSEDCONSOLIDATEDBALANCESHEETSParenthetical</Role>
      <ShortName>UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>0000005 - Statement - UNAUDITED CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS??? EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/UNAUDITEDCONDENSEDCONSOLIDATEDSTATEMENTOFCHANGESINSTOCKHOLDERSEQUITY</Role>
      <ShortName>UNAUDITED CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS??? EQUITY</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>0000006 - Statement - UNAUDITED CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS??? EQUITY (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/UNAUDITEDCONDENSEDCONSOLIDATEDSTATEMENTOFCHANGESINSTOCKHOLDERSEQUITYParenthetical</Role>
      <ShortName>UNAUDITED CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS??? EQUITY (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>0000007 - Statement - UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/UNAUDITEDCONDENSEDCONSOLIDATEDSTATEMENTSOFCASHFLOWS</Role>
      <ShortName>UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>0000008 - Disclosure - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/SummaryofSignificantAccountingPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>0000009 - Disclosure - Reportable Segments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/ReportableSegments</Role>
      <ShortName>Reportable Segments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>0000010 - Disclosure - Disaggregation of Revenue</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/DisaggregationofRevenue</Role>
      <ShortName>Disaggregation of Revenue</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>0000011 - Disclosure - Allowance for Credit Losses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/AllowanceforCreditLosses</Role>
      <ShortName>Allowance for Credit Losses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>0000012 - Disclosure - Other Assets, Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/OtherAssetsNet</Role>
      <ShortName>Other Assets, Net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>0000013 - Disclosure - Current Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/CurrentLiabilities</Role>
      <ShortName>Current Liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>0000014 - Disclosure - Credit Facility</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/CreditFacility</Role>
      <ShortName>Credit Facility</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>0000015 - Disclosure - Other Long-Term Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/OtherLongTermLiabilities</Role>
      <ShortName>Other Long-Term Liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>0000016 - Disclosure - Stock-based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/StockbasedCompensation</Role>
      <ShortName>Stock-based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>0000017 - Disclosure - Derivative Instrument and Hedging Activity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/DerivativeInstrumentandHedgingActivity</Role>
      <ShortName>Derivative Instrument and Hedging Activity</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>0000018 - Disclosure - Fair Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/FairValueMeasurements</Role>
      <ShortName>Fair Value Measurements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>0000019 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/CommitmentsandContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>995410 - Disclosure - Pay vs Performance Disclosure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/PvpDisclosure</Role>
      <ShortName>Pay vs Performance Disclosure</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>995445 - Disclosure - Insider Trading Arrangements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements</Role>
      <ShortName>Insider Trading Arrangements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>9954701 - Disclosure - Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/SummaryofSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.kforce.com/role/SummaryofSignificantAccountingPolicies</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>9954702 - Disclosure - Reportable Segments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/ReportableSegmentsTables</Role>
      <ShortName>Reportable Segments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kforce.com/role/ReportableSegments</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>9954703 - Disclosure - Disaggregation of Revenue (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/DisaggregationofRevenueTables</Role>
      <ShortName>Disaggregation of Revenue (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kforce.com/role/DisaggregationofRevenue</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>9954704 - Disclosure - Allowance for Credit Losses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/AllowanceforCreditLossesTables</Role>
      <ShortName>Allowance for Credit Losses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kforce.com/role/AllowanceforCreditLosses</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>9954705 - Disclosure - Other Assets, Net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/OtherAssetsNetTables</Role>
      <ShortName>Other Assets, Net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kforce.com/role/OtherAssetsNet</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>9954706 - Disclosure - Current Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/CurrentLiabilitiesTables</Role>
      <ShortName>Current Liabilities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kforce.com/role/CurrentLiabilities</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>9954707 - Disclosure - Other Long-Term Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/OtherLongTermLiabilitiesTables</Role>
      <ShortName>Other Long-Term Liabilities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kforce.com/role/OtherLongTermLiabilities</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>9954708 - Disclosure - Stock-based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/StockbasedCompensationTables</Role>
      <ShortName>Stock-based Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kforce.com/role/StockbasedCompensation</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>9954709 - Disclosure - Derivative Instrument and Hedging Activity (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/DerivativeInstrumentandHedgingActivityTables</Role>
      <ShortName>Derivative Instrument and Hedging Activity (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kforce.com/role/DerivativeInstrumentandHedgingActivity</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>9954710 - Disclosure - Summary of Significant Accounting Policies - Health Insurance (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/SummaryofSignificantAccountingPoliciesHealthInsuranceDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Health Insurance (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>9954711 - Disclosure - Summary of Significant Accounting Policies - Earnings per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/SummaryofSignificantAccountingPoliciesEarningsperShareDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Earnings per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>9954712 - Disclosure - Summary of Significant Accounting Policies - Equity Method Investment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/SummaryofSignificantAccountingPoliciesEquityMethodInvestmentDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Equity Method Investment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>9954713 - Disclosure - Summary of Significant Accounting Policies - Exercise Tax (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/SummaryofSignificantAccountingPoliciesExerciseTaxDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Exercise Tax (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>9954714 - Disclosure - Reportable Segments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/ReportableSegmentsDetails</Role>
      <ShortName>Reportable Segments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.kforce.com/role/ReportableSegmentsTables</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>9954715 - Disclosure - Disaggregation of Revenue (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/DisaggregationofRevenueDetails</Role>
      <ShortName>Disaggregation of Revenue (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.kforce.com/role/DisaggregationofRevenueTables</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>9954716 - Disclosure - Allowance for Credit Losses - Allowance for Credit Losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/AllowanceforCreditLossesAllowanceforCreditLossesDetails</Role>
      <ShortName>Allowance for Credit Losses - Allowance for Credit Losses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>9954717 - Disclosure - Allowance for Credit Losses - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/AllowanceforCreditLossesNarrativeDetails</Role>
      <ShortName>Allowance for Credit Losses - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>9954718 - Disclosure - Other Assets, Net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/OtherAssetsNetDetails</Role>
      <ShortName>Other Assets, Net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.kforce.com/role/OtherAssetsNetTables</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>9954719 - Disclosure - Current Liabilities - Schedule of Accounts Payable and Accrued Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/CurrentLiabilitiesScheduleofAccountsPayableandAccruedLiabilitiesDetails</Role>
      <ShortName>Current Liabilities - Schedule of Accounts Payable and Accrued Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>9954720 - Disclosure - Credit Facility (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/CreditFacilityDetails</Role>
      <ShortName>Credit Facility (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.kforce.com/role/CreditFacility</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>9954721 - Disclosure - Other Long-Term Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/OtherLongTermLiabilitiesDetails</Role>
      <ShortName>Other Long-Term Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.kforce.com/role/OtherLongTermLiabilitiesTables</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>9954722 - Disclosure - Stock-based Compensation - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/StockbasedCompensationNarrativeDetails</Role>
      <ShortName>Stock-based Compensation - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>9954723 - Disclosure - Stock-based Compensation - Summary of Restricted Stock Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/StockbasedCompensationSummaryofRestrictedStockActivityDetails</Role>
      <ShortName>Stock-based Compensation - Summary of Restricted Stock Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>9954724 - Disclosure - Derivative Instrument and Hedging Activity - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/DerivativeInstrumentandHedgingActivityNarrativeDetails</Role>
      <ShortName>Derivative Instrument and Hedging Activity - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>9954725 - Disclosure - Derivative Instrument and Hedging Activity - Accumulated Derivative Instrument Gain (Loss) Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/DerivativeInstrumentandHedgingActivityAccumulatedDerivativeInstrumentGainLossActivityDetails</Role>
      <ShortName>Derivative Instrument and Hedging Activity - Accumulated Derivative Instrument Gain (Loss) Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="kfrc-20230630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>9954726 - Disclosure - Commitments and Contingencies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kforce.com/role/CommitmentsandContingenciesDetails</Role>
      <ShortName>Commitments and Contingencies (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.kforce.com/role/CommitmentsandContingencies</ParentRole>
      <Position>47</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File doctype="10-Q" original="kfrc-20230630.htm">kfrc-20230630.htm</File>
    <File>exhibit101-firstamendmentt.htm</File>
    <File>exhibit311q22023.htm</File>
    <File>exhibit312q22023.htm</File>
    <File>exhibit321q22023.htm</File>
    <File>exhibit322q22023.htm</File>
    <File>kfrc-20230630.xsd</File>
    <File>kfrc-20230630_cal.xml</File>
    <File>kfrc-20230630_def.xml</File>
    <File>kfrc-20230630_lab.xml</File>
    <File>kfrc-20230630_pre.xml</File>
  </InputFiles>
  <SupplementalFiles>
    <File>kfrc-20230630_g1.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="518">http://fasb.org/us-gaap/2023</BaseTaxonomy>
    <BaseTaxonomy items="29">http://xbrl.sec.gov/dei/2023</BaseTaxonomy>
    <BaseTaxonomy items="4">http://xbrl.sec.gov/ecd/2023</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
