<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.22.0.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>313</ContextCount>
  <ElementCount>517</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>106</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>10</UnitCount>
  <MyReports>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>100000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>100010 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/StatementConsolidatedBalanceSheets</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>100020 - Statement - Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/StatementConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>100030 - Statement - Consolidated Statements of Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/StatementConsolidatedStatementsOfIncome</Role>
      <ShortName>Consolidated Statements of Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>100040 - Statement - Consolidated Statements of Income (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/StatementConsolidatedStatementsOfIncomeParenthetical</Role>
      <ShortName>Consolidated Statements of Income (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>100050 - Statement - Consolidated Statements of Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/StatementConsolidatedStatementsOfComprehensiveIncome</Role>
      <ShortName>Consolidated Statements of Comprehensive Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>100060 - Statement - Consolidated Statements of Comprehensive Income (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/StatementConsolidatedStatementsOfComprehensiveIncomeParenthetical</Role>
      <ShortName>Consolidated Statements of Comprehensive Income (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>100070 - Statement - Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/StatementConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>100080 - Statement - Consolidated Statements of Shareholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/StatementConsolidatedStatementsOfShareholdersEquity</Role>
      <ShortName>Consolidated Statements of Shareholders' Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>100090 - Statement - Consolidated Statements of Shareholders' Equity (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/StatementConsolidatedStatementsOfShareholdersEquityParenthetical</Role>
      <ShortName>Consolidated Statements of Shareholders' Equity (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>100100 - Disclosure - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>100110 - Disclosure - Recent Accounting Pronouncements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureRecentAccountingPronouncements</Role>
      <ShortName>Recent Accounting Pronouncements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>100120 - Disclosure - Revenue Recognition</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureRevenueRecognition</Role>
      <ShortName>Revenue Recognition</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>100130 - Disclosure - Acquisitions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureAcquisitions</Role>
      <ShortName>Acquisitions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>100140 - Disclosure - Marketable Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureMarketableSecurities</Role>
      <ShortName>Marketable Securities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>100150 - Disclosure - Accounts Receivable</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureAccountsReceivable</Role>
      <ShortName>Accounts Receivable</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>100160 - Disclosure - Property and Equipment</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosurePropertyAndEquipment</Role>
      <ShortName>Property and Equipment</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>100170 - Disclosure - Accrued Expenses and Other Current Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureAccruedExpensesAndOtherCurrentLiabilities</Role>
      <ShortName>Accrued Expenses and Other Current Liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>100180 - Disclosure - Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureDebt</Role>
      <ShortName>Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>100190 - Disclosure - Fair Value Measurements and Disclosures</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureFairValueMeasurementsAndDisclosures</Role>
      <ShortName>Fair Value Measurements and Disclosures</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>100200 - Disclosure - Transactions with Affiliates</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureTransactionsWithAffiliates</Role>
      <ShortName>Transactions with Affiliates</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>100210 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureIncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>100220 - Disclosure - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureLeases</Role>
      <ShortName>Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>100230 - Disclosure - Retirement Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureRetirementPlans</Role>
      <ShortName>Retirement Plans</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>100240 - Disclosure - Stock Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureStockBasedCompensation</Role>
      <ShortName>Stock Based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>100250 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>100260 - Disclosure - Earnings Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureEarningsPerShare</Role>
      <ShortName>Earnings Per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>100270 - Disclosure - Segment Reporting</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSegmentReporting</Role>
      <ShortName>Segment Reporting</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>100280 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSubsequentEvents</Role>
      <ShortName>Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>100290 - Disclosure - Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPolicies</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>100300 - Disclosure - Summary of Significant Accounting Policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesTables</Role>
      <ShortName>Summary of Significant Accounting Policies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPolicies</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>100310 - Disclosure - Revenue Recognition (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureRevenueRecognitionTables</Role>
      <ShortName>Revenue Recognition (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.goutsi.com/20211231/taxonomy/role/DisclosureRevenueRecognition</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>100320 - Disclosure - Acquisitions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureAcquisitionsTables</Role>
      <ShortName>Acquisitions (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.goutsi.com/20211231/taxonomy/role/DisclosureAcquisitions</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>100330 - Disclosure - Marketable Securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureMarketableSecuritiesTables</Role>
      <ShortName>Marketable Securities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.goutsi.com/20211231/taxonomy/role/DisclosureMarketableSecurities</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>100340 - Disclosure - Accounts Receivable (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureAccountsReceivableTables</Role>
      <ShortName>Accounts Receivable (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.goutsi.com/20211231/taxonomy/role/DisclosureAccountsReceivable</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>100350 - Disclosure - Property and Equipment (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosurePropertyAndEquipmentTables</Role>
      <ShortName>Property and Equipment (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.goutsi.com/20211231/taxonomy/role/DisclosurePropertyAndEquipment</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>100360 - Disclosure - Accrued Expenses and Other Current Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureAccruedExpensesAndOtherCurrentLiabilitiesTables</Role>
      <ShortName>Accrued Expenses and Other Current Liabilities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.goutsi.com/20211231/taxonomy/role/DisclosureAccruedExpensesAndOtherCurrentLiabilities</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>100370 - Disclosure - Debt (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureDebtTables</Role>
      <ShortName>Debt (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.goutsi.com/20211231/taxonomy/role/DisclosureDebt</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>100380 - Disclosure - Fair Value Measurements and Disclosures (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureFairValueMeasurementsAndDisclosuresTables</Role>
      <ShortName>Fair Value Measurements and Disclosures (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.goutsi.com/20211231/taxonomy/role/DisclosureFairValueMeasurementsAndDisclosures</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>100390 - Disclosure - Transactions with Affiliates (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureTransactionsWithAffiliatesTables</Role>
      <ShortName>Transactions with Affiliates (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.goutsi.com/20211231/taxonomy/role/DisclosureTransactionsWithAffiliates</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>100400 - Disclosure - Income Taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureIncomeTaxesTables</Role>
      <ShortName>Income Taxes (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.goutsi.com/20211231/taxonomy/role/DisclosureIncomeTaxes</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>100410 - Disclosure - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureLeasesTables</Role>
      <ShortName>Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.goutsi.com/20211231/taxonomy/role/DisclosureLeases</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>100420 - Disclosure - Stock Based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureStockBasedCompensationTables</Role>
      <ShortName>Stock Based Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.goutsi.com/20211231/taxonomy/role/DisclosureStockBasedCompensation</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>100430 - Disclosure - Segment Reporting (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSegmentReportingTables</Role>
      <ShortName>Segment Reporting (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSegmentReporting</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>100440 - Disclosure - Summary of Significant Accounting Policies - Schedule of Inventories (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesScheduleOfInventoriesDetail</Role>
      <ShortName>Summary of Significant Accounting Policies - Schedule of Inventories (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>100450 - Disclosure - Summary of Significant Accounting Policies - Estimated Useful Lives of Assets (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesEstimatedUsefulLivesOfAssetsDetail</Role>
      <ShortName>Summary of Significant Accounting Policies - Estimated Useful Lives of Assets (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>100460 - Disclosure - Summary of Significant Accounting Policies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail</Role>
      <ShortName>Summary of Significant Accounting Policies - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>100470 - Disclosure - Summary of Significant Accounting Policies - Schedule of Identifiable Intangible Assets (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesScheduleOfIdentifiableIntangibleAssetsDetail</Role>
      <ShortName>Summary of Significant Accounting Policies - Schedule of Identifiable Intangible Assets (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>100480 - Disclosure - Summary of Significant Accounting Policies - Estimated Amortization Expense by Year (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesEstimatedAmortizationExpenseByYearDetail</Role>
      <ShortName>Summary of Significant Accounting Policies - Estimated Amortization Expense by Year (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>100490 - Disclosure - Summary of Significant Accounting Policies - Schedule of Changes in Carrying Amount of Goodwill (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesScheduleOfChangesInCarryingAmountOfGoodwillDetail</Role>
      <ShortName>Summary of Significant Accounting Policies - Schedule of Changes in Carrying Amount of Goodwill (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>100500 - Disclosure - Recent Accounting Pronouncements - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureRecentAccountingPronouncementsAdditionalInformationDetail</Role>
      <ShortName>Recent Accounting Pronouncements - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>100510 - Disclosure - Revenue Recognition - Aditional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureRevenueRecognitionAditionalInformationDetail</Role>
      <ShortName>Revenue Recognition - Aditional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>100520 - Disclosure - Revenue Recognition - Contact Balances Associated with Customers (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureRevenueRecognitionContactBalancesAssociatedWithCustomersDetail</Role>
      <ShortName>Revenue Recognition - Contact Balances Associated with Customers (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>100530 - Disclosure - Acquisitions - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureAcquisitionsAdditionalInformationDetail</Role>
      <ShortName>Acquisitions - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>100540 - Disclosure - Acquisitions - Summary of Allocation of Purchase Price (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureAcquisitionsSummaryOfAllocationOfPurchasePriceDetail</Role>
      <ShortName>Acquisitions - Summary of Allocation of Purchase Price (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>100550 - Disclosure - Acquisitions - Summary of Unaudited Pro Forma Results of Operations (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureAcquisitionsSummaryOfUnauditedProFormaResultsOfOperationsDetail</Role>
      <ShortName>Acquisitions - Summary of Unaudited Pro Forma Results of Operations (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>100560 - Disclosure - Marketable Securities - Schedule of Market Value, Cost and Unrealized Gains (Losses) on Equity Securities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureMarketableSecuritiesScheduleOfMarketValueCostAndUnrealizedGainsLossesOnEquitySecuritiesDetail</Role>
      <ShortName>Marketable Securities - Schedule of Market Value, Cost and Unrealized Gains (Losses) on Equity Securities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>100570 - Disclosure - Marketable Securities - Schedule of Gross Unrealized Gains and Losses on Marketable Securities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureMarketableSecuritiesScheduleOfGrossUnrealizedGainsAndLossesOnMarketableSecuritiesDetail</Role>
      <ShortName>Marketable Securities - Schedule of Gross Unrealized Gains and Losses on Marketable Securities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>100580 - Disclosure - Marketable Securities - Summary of Net Realized Gains (Losses) on Marketable Equity Securities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureMarketableSecuritiesSummaryOfNetRealizedGainsLossesOnMarketableEquitySecuritiesDetail</Role>
      <ShortName>Marketable Securities - Summary of Net Realized Gains (Losses) on Marketable Equity Securities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>100590 - Disclosure - Marketable Securities - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureMarketableSecuritiesAdditionalInformationDetail</Role>
      <ShortName>Marketable Securities - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>100600 - Disclosure - Accounts Receivable - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureAccountsReceivableAdditionalInformationDetail</Role>
      <ShortName>Accounts Receivable - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>100610 - Disclosure - Accounts Receivable - Summary of Activity in Allowance for Doubtful Accounts (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureAccountsReceivableSummaryOfActivityInAllowanceForDoubtfulAccountsDetail</Role>
      <ShortName>Accounts Receivable - Summary of Activity in Allowance for Doubtful Accounts (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>100620 - Disclosure - Property and Equipment - Schedule of Property and Equipment (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosurePropertyAndEquipmentScheduleOfPropertyAndEquipmentDetail</Role>
      <ShortName>Property and Equipment - Schedule of Property and Equipment (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>100630 - Disclosure - Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureAccruedExpensesAndOtherCurrentLiabilitiesScheduleOfAccruedExpensesAndOtherCurrentLiabilitiesDetail</Role>
      <ShortName>Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>100640 - Disclosure - Debt - Details of Debt (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureDebtDetailsOfDebtDetail</Role>
      <ShortName>Debt - Details of Debt (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>100660 - Disclosure - Debt - Details of Debt (Parenthetical) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureDebtDetailsOfDebtParentheticalDetail</Role>
      <ShortName>Debt - Details of Debt (Parenthetical) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>100670 - Disclosure - Debt - Summary of Maturities of Principal Repayment Obligations (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureDebtSummaryOfMaturitiesOfPrincipalRepaymentObligationsDetail</Role>
      <ShortName>Debt - Summary of Maturities of Principal Repayment Obligations (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>100680 - Disclosure - Debt - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureDebtAdditionalInformationDetail</Role>
      <ShortName>Debt - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>100690 - Disclosure - Fair Value Measurements and Disclosures - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureFairValueMeasurementsAndDisclosuresFinancialAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetail</Role>
      <ShortName>Fair Value Measurements and Disclosures - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>100700 - Disclosure - Fair Value Measurement and Disclosures - Summary of Carrying Values and Estimated Fair Values of Promissory Notes (Detail)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureFairValueMeasurementAndDisclosuresSummaryOfCarryingValuesAndEstimatedFairValuesOfPromissoryNotesDetail</Role>
      <ShortName>Fair Value Measurement and Disclosures - Summary of Carrying Values and Estimated Fair Values of Promissory Notes (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>100710 - Disclosure - Transactions with Affiliates - Schedule of Amounts Charged to UTSI (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureTransactionsWithAffiliatesScheduleOfAmountsChargedToUTSIDetail</Role>
      <ShortName>Transactions with Affiliates - Schedule of Amounts Charged to UTSI (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>100720 - Disclosure - Transactions with Affiliates - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureTransactionsWithAffiliatesAdditionalInformationDetail</Role>
      <ShortName>Transactions with Affiliates - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>100730 - Disclosure - Transactions with Affiliates - Schedule of Services Provided to Affiliates (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureTransactionsWithAffiliatesScheduleOfServicesProvidedToAffiliatesDetail</Role>
      <ShortName>Transactions with Affiliates - Schedule of Services Provided to Affiliates (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>100740 - Disclosure - Income Taxes - Summary of Income (Loss) Related to U.S. and Non-U.S. Operations (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureIncomeTaxesSummaryOfIncomeLossRelatedToUSAndNonUSOperationsDetail</Role>
      <ShortName>Income Taxes - Summary of Income (Loss) Related to U.S. and Non-U.S. Operations (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>100750 - Disclosure - Income Taxes - Provision (Benefit) for Income Taxes Attributable to Income from Continuing Operations (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureIncomeTaxesProvisionBenefitForIncomeTaxesAttributableToIncomeFromContinuingOperationsDetail</Role>
      <ShortName>Income Taxes - Provision (Benefit) for Income Taxes Attributable to Income from Continuing Operations (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>100760 - Disclosure - Income Taxes - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail</Role>
      <ShortName>Income Taxes - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>100770 - Disclosure - Income Taxes - Deferred Income Tax Assets and Liabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureIncomeTaxesDeferredIncomeTaxAssetsAndLiabilitiesDetail</Role>
      <ShortName>Income Taxes - Deferred Income Tax Assets and Liabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>77</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>100780 - Disclosure - Income Taxes - Income Tax Expense Attributable to Income from Continuing Operations Differs from Statutory Rates (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureIncomeTaxesIncomeTaxExpenseAttributableToIncomeFromContinuingOperationsDiffersFromStatutoryRatesDetail</Role>
      <ShortName>Income Taxes - Income Tax Expense Attributable to Income from Continuing Operations Differs from Statutory Rates (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>78</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>100790 - Disclosure - Income Taxes - Changes in Company's Gross Unrecognized Tax Benefits (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureIncomeTaxesChangesInCompanySGrossUnrecognizedTaxBenefitsDetail</Role>
      <ShortName>Income Taxes - Changes in Company's Gross Unrecognized Tax Benefits (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>79</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>100800 - Disclosure - Leases - Summary of Lease Costs (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureLeasesSummaryOfLeaseCostsDetail</Role>
      <ShortName>Leases - Summary of Lease Costs (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>80</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>100810 - Disclosure - Leases - Summary of Other Lease Related Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureLeasesSummaryOfOtherLeaseRelatedInformationDetail</Role>
      <ShortName>Leases - Summary of Other Lease Related Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>81</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>100820 - Disclosure - Leases - Schedule of Future Minimum Lease Payments Under Operating Leases (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureLeasesScheduleOfFutureMinimumLeasePaymentsUnderOperatingLeasesDetail</Role>
      <ShortName>Leases - Schedule of Future Minimum Lease Payments Under Operating Leases (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>82</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>100840 - Disclosure - Retirement Plans - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureRetirementPlansAdditionalInformationDetail</Role>
      <ShortName>Retirement Plans - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>83</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>100850 - Disclosure - Stock Based Compensation - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureStockBasedCompensationAdditionalInformationDetail</Role>
      <ShortName>Stock Based Compensation - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>84</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>100860 - Disclosure - Stock Based Compensation - Summary of Status of Nonvested Shares (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStatusOfNonvestedSharesDetail</Role>
      <ShortName>Stock Based Compensation - Summary of Status of Nonvested Shares (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>85</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>100870 - Disclosure - Commitments and Contingencies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetail</Role>
      <ShortName>Commitments and Contingencies - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>86</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>100880 - Disclosure - Earnings Per Share - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureEarningsPerShareAdditionalInformationDetail</Role>
      <ShortName>Earnings Per Share - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>87</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>100890 - Disclosure - Segment Reporting - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSegmentReportingAdditionalInformationDetail</Role>
      <ShortName>Segment Reporting - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>88</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>100900 - Disclosure - Segment Reporting - Summary of Company's Reportable Segment Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSegmentReportingSummaryOfCompanySReportableSegmentInformationDetail</Role>
      <ShortName>Segment Reporting - Summary of Company's Reportable Segment Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>89</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>100910 - Disclosure - Segment Reporting - Revenues Attributed to Geographic Areas (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSegmentReportingRevenuesAttributedToGeographicAreasDetail</Role>
      <ShortName>Segment Reporting - Revenues Attributed to Geographic Areas (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>90</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>100920 - Disclosure - Segment Reporting - Net Long-Lived Assets by Geographic Areas (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSegmentReportingNetLongLivedAssetsByGeographicAreasDetail</Role>
      <ShortName>Segment Reporting - Net Long-Lived Assets by Geographic Areas (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>91</Position>
    </Report>
    <Report instance="ulh-10k_20211231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>100930 - Disclosure - Subsequent Events - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.goutsi.com/20211231/taxonomy/role/DisclosureSubsequentEventsAdditionalInformationDetail</Role>
      <ShortName>Subsequent Events - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>92</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-K" original="ulh-10k_20211231.htm">ulh-10k_20211231.htm</File>
    <File>ulh-20211231.xsd</File>
    <File>ulh-20211231_cal.xml</File>
    <File>ulh-20211231_def.xml</File>
    <File>ulh-20211231_lab.xml</File>
    <File>ulh-20211231_pre.xml</File>
    <File>ulh-ex211_7.htm</File>
    <File>ulh-ex231_144.htm</File>
    <File>ulh-ex232_10.htm</File>
    <File>ulh-ex311_6.htm</File>
    <File>ulh-ex312_8.htm</File>
    <File>ulh-ex321_11.htm</File>
    <File>ulh-ex42_9.htm</File>
  </InputFiles>
  <SupplementalFiles>
    <File>gyay05w0vsr3000001.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="1023">http://fasb.org/us-gaap/2021-01-31</BaseTaxonomy>
    <BaseTaxonomy items="40">http://xbrl.sec.gov/dei/2021q4</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
