<?xml version="1.0" encoding="utf-8"?>
<xbrl
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:dei="http://xbrl.sec.gov/dei/2025"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:navi="http://navient.com/20260604"
  xmlns:us-gaap="http://fasb.org/us-gaap/2025"
  xmlns:xbrldi="http://xbrl.org/2006/xbrldi"
  xmlns:xlink="http://www.w3.org/1999/xlink">
    <link:schemaRef xlink:href="navi-20260604.xsd" xlink:type="simple"/>
    <context id="c20260604to20260604">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001593538</identifier>
        </entity>
        <period>
            <startDate>2026-06-04</startDate>
            <endDate>2026-06-04</endDate>
        </period>
    </context>
    <context id="c20260604to20260604_StatementClassOfStockAxis_CommonStockMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001593538</identifier>
            <segment>
                <xbrldi:explicitMember dimension="us-gaap:StatementClassOfStockAxis">us-gaap:CommonStockMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-06-04</startDate>
            <endDate>2026-06-04</endDate>
        </period>
    </context>
    <context id="c20260604to20260604_StatementClassOfStockAxis_PreferredStockPurchaseRightsMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001593538</identifier>
            <segment>
                <xbrldi:explicitMember dimension="us-gaap:StatementClassOfStockAxis">navi:PreferredStockPurchaseRightsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-06-04</startDate>
            <endDate>2026-06-04</endDate>
        </period>
    </context>
    <context id="c20260604to20260604_StatementClassOfStockAxis_SixSeniorNotesDueDecember152043Member">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0001593538</identifier>
            <segment>
                <xbrldi:explicitMember dimension="us-gaap:StatementClassOfStockAxis">navi:SixSeniorNotesDueDecember152043Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-06-04</startDate>
            <endDate>2026-06-04</endDate>
        </period>
    </context>
    <dei:AmendmentFlag
      contextRef="c20260604to20260604"
      id="Fact_8ca244a31a0d404b9c24b7d08bea5a44">false</dei:AmendmentFlag>
    <dei:EntityCentralIndexKey
      contextRef="c20260604to20260604"
      id="Fact_bee40984348d41e8b4b62e260f3b75be">0001593538</dei:EntityCentralIndexKey>
    <dei:DocumentType
      contextRef="c20260604to20260604"
      id="Fact_861cc4649140493b90874035ea2fb6b7">8-K</dei:DocumentType>
    <dei:DocumentPeriodEndDate
      contextRef="c20260604to20260604"
      id="Fact_b007b6d78a184dcf8e6e637af68396f6">2026-06-04</dei:DocumentPeriodEndDate>
    <dei:EntityRegistrantName
      contextRef="c20260604to20260604"
      id="Fact_43398756e35c4ddcaed1bb7c3b6376de">Navient Corporation</dei:EntityRegistrantName>
    <dei:EntityIncorporationStateCountryCode
      contextRef="c20260604to20260604"
      id="Fact_94a24ee0e9004af6a2e33f4908fd7870">DE</dei:EntityIncorporationStateCountryCode>
    <dei:EntityFileNumber
      contextRef="c20260604to20260604"
      id="Fact_56fd3599c2b242b8b16a8def86c61091">001-36228</dei:EntityFileNumber>
    <dei:EntityTaxIdentificationNumber
      contextRef="c20260604to20260604"
      id="Fact_24bba4bddcc9481f979568e2558d7f52">46-4054283</dei:EntityTaxIdentificationNumber>
    <dei:EntityAddressAddressLine1
      contextRef="c20260604to20260604"
      id="Fact_51a6e75df54142d0b7befea01840222d">13865 Sunrise Valley Drive</dei:EntityAddressAddressLine1>
    <dei:EntityAddressCityOrTown
      contextRef="c20260604to20260604"
      id="Fact_acad6161c77d40d3ae0b6abe7e176d50">Herndon</dei:EntityAddressCityOrTown>
    <dei:EntityAddressStateOrProvince
      contextRef="c20260604to20260604"
      id="Fact_7443884be006466ba8c38cb76a7be777">VA</dei:EntityAddressStateOrProvince>
    <dei:EntityAddressPostalZipCode
      contextRef="c20260604to20260604"
      id="Fact_d532c93ffe0241c18501066df8662394">20171</dei:EntityAddressPostalZipCode>
    <dei:CityAreaCode
      contextRef="c20260604to20260604"
      id="Fact_a719fe664afa4dabb7b8d5c00a53aeac">703</dei:CityAreaCode>
    <dei:LocalPhoneNumber
      contextRef="c20260604to20260604"
      id="Fact_99047b7ab40b4a6ca5eb2fd09fe145b4">810-3000</dei:LocalPhoneNumber>
    <dei:WrittenCommunications
      contextRef="c20260604to20260604"
      id="Fact_253444ef8a4d4ae49c0b4ab21521ee8a">false</dei:WrittenCommunications>
    <dei:SolicitingMaterial
      contextRef="c20260604to20260604"
      id="Fact_fe139c3595d844ceb71d5442ae419efe">false</dei:SolicitingMaterial>
    <dei:PreCommencementTenderOffer
      contextRef="c20260604to20260604"
      id="Fact_c63fae2185b74b53826d658c81045c5f">false</dei:PreCommencementTenderOffer>
    <dei:PreCommencementIssuerTenderOffer
      contextRef="c20260604to20260604"
      id="Fact_1fc1309d56fd42e8b58ef17ac1d36058">false</dei:PreCommencementIssuerTenderOffer>
    <dei:Security12bTitle
      contextRef="c20260604to20260604_StatementClassOfStockAxis_CommonStockMember"
      id="Fact_42f6b4c84ae048a780b785dc0a59eb47">Common stock, par value $.01 per share</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="c20260604to20260604_StatementClassOfStockAxis_CommonStockMember"
      id="Fact_8f8f8ad97db147d2bfd4bef37077def9">NAVI</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="c20260604to20260604_StatementClassOfStockAxis_CommonStockMember"
      id="Fact_61bea150130a4687a4b5c305a27bd2d4">NASDAQ</dei:SecurityExchangeName>
    <dei:Security12bTitle
      contextRef="c20260604to20260604_StatementClassOfStockAxis_SixSeniorNotesDueDecember152043Member"
      id="Fact_8321f80211744c13849958b6f8e86ce4">6% Senior Notes due December 15, 2043</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="c20260604to20260604_StatementClassOfStockAxis_SixSeniorNotesDueDecember152043Member"
      id="Fact_1619b00686d54c6aab1d6597c9221498">JSM</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="c20260604to20260604_StatementClassOfStockAxis_SixSeniorNotesDueDecember152043Member"
      id="Fact_1281a9647f054540bb88f48148befa16">NASDAQ</dei:SecurityExchangeName>
    <dei:Security12bTitle
      contextRef="c20260604to20260604_StatementClassOfStockAxis_PreferredStockPurchaseRightsMember"
      id="Fact_70f7ab92a3504871b1e2584f27572ceb">Preferred Stock Purchase Rights</dei:Security12bTitle>
    <dei:TradingSymbol
      contextRef="c20260604to20260604_StatementClassOfStockAxis_PreferredStockPurchaseRightsMember"
      id="Fact_3a37b7801720405385f53a60853417a7">None</dei:TradingSymbol>
    <dei:SecurityExchangeName
      contextRef="c20260604to20260604_StatementClassOfStockAxis_PreferredStockPurchaseRightsMember"
      id="Fact_31127dc1f95f43a38101aa550b81bfbf">NASDAQ</dei:SecurityExchangeName>
    <dei:EntityEmergingGrowthCompany
      contextRef="c20260604to20260604"
      id="Fact_0cba17517fe4496882bde74547b3423f">false</dei:EntityEmergingGrowthCompany>
</xbrl>
