<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>440</ContextCount>
  <ElementCount>34</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>100</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>3</UnitCount>
  <MyReports>
    <Report instance="broostone_n-csr.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>030000 - Disclosure - Form N-CSR Cover</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/oef/role/NcsrCover</Role>
      <ShortName>Form N-CSR Cover</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="broostone_n-csr.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>030001 - Disclosure - Shareholder Report</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/oef/role/ShareholderReport</Role>
      <ShortName>Shareholder Report</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="broostone_n-csr.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>040010 - Disclosure - Shareholder Report, Line Graph (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/oef/role/ShareholderReportLineGraphDetails</Role>
      <ShortName>Shareholder Report, Line Graph (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="broostone_n-csr.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>040015 - Disclosure - Shareholder Report, Average Annual Return (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/oef/role/ShareholderReportAverageAnnualReturnDetails</Role>
      <ShortName>Shareholder Report, Average Annual Return (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="broostone_n-csr.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>040020 - Disclosure - Shareholder Report, Holdings (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/oef/role/ShareholderReportHoldingsDetails</Role>
      <ShortName>Shareholder Report, Holdings (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>5</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="N-CSR" isDefinitelyNotFs="true" isNcsr="true" isOEF="true" isRRorOEF="true" isUsgaap="true" original="broostone_n-csr.htm">broostone_n-csr.htm</File>
    <File>nlft4-20260531.xsd</File>
  </InputFiles>
  <SupplementalFiles>
    <File>br001_v1.jpg</File>
    <File>br002_v1.jpg</File>
    <File>br003_v1.jpg</File>
    <File>i0bb63ce780ec7227e9863776.jpg</File>
    <File>i1a70038497f22e7f0136c122.jpg</File>
    <File>i252cf143bbd66279cd9efa18.jpg</File>
    <File>i31b59e119b7904356a0dd952.jpg</File>
    <File>i3876b44b7abea3ec6282059b.jpg</File>
    <File>i42bdca572cd0d67c77fc5ea2.jpg</File>
    <File>i4428146fafca6e9381c04b52.jpg</File>
    <File>i45070d337f4c620440b9b777.jpg</File>
    <File>i4d95bfb8733e9cffb50678ee.jpg</File>
    <File>i6878d66c2392e1755d2979b4.jpg</File>
    <File>i6922dbc42d47db6d92580b32.jpg</File>
    <File>i8cca846b83100cf3067053c4.jpg</File>
    <File>i91ba384d2ae13714614037fc.jpg</File>
    <File>i93ba5fd69e277306a499f89e.jpg</File>
    <File>ia6b1699420fe695cf06f63ec.jpg</File>
    <File>iabf8aeda5a53826f6c26775a.jpg</File>
    <File>iada8f1a0de76683d80947235.jpg</File>
    <File>iaec4609ba928e9674bd9c8bb.jpg</File>
    <File>ib2911a6d0a46c7ce8f76fc31.jpg</File>
    <File>ib4da2363b120bdc939f35302.jpg</File>
    <File>ib5873502cc8e18cd38149c70.jpg</File>
    <File>ib841fbbcea226b032c7d4260.jpg</File>
    <File>ibe7a4bc4b1c29af039df1ccf.jpg</File>
    <File>ic8818a09b343db89ffaa1e5c.jpg</File>
    <File>icc087b37eed00779faa68a31.jpg</File>
    <File>id08c8101bccba22999d4a49b.jpg</File>
    <File>ie0c4ad6f56a33225330da4dc.jpg</File>
    <File>ie3e8012c5d876b76951400a2.jpg</File>
    <File>ie914489bb7ffd4aab6f3d42e.jpg</File>
    <File>if4e2384618514113d72b009e.jpg</File>
    <File>ifaa4986bb305eaf45e95c4b9.jpg</File>
    <File>iff2b6bc3d0a3414913ddc5f4.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="16">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="30">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="602">http://xbrl.sec.gov/oef/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>false</HasPresentationLinkbase>
  <HasCalculationLinkbase>false</HasCalculationLinkbase>
</FilingSummary>
