3.26.1 html 162 231 1 false 57 0 false 5 false false R1.htm 0000001 - Document - Cover Sheet http://www.ul.com/role/Cover Cover Cover 1 false false R2.htm 9952151 - Statement - Condensed Consolidated Statements of Operations Sheet http://www.ul.com/role/CondensedConsolidatedStatementsofOperations Condensed Consolidated Statements of Operations Statements 2 false false R3.htm 9952152 - Statement - Condensed Consolidated Statements of Comprehensive Income Sheet http://www.ul.com/role/CondensedConsolidatedStatementsofComprehensiveIncome Condensed Consolidated Statements of Comprehensive Income Statements 3 false false R4.htm 9952153 - Statement - Condensed Consolidated Balance Sheets Sheet http://www.ul.com/role/CondensedConsolidatedBalanceSheets Condensed Consolidated Balance Sheets Statements 4 false false R5.htm 9952154 - Statement - Condensed Consolidated Balance Sheets (Parenthetical) Sheet http://www.ul.com/role/CondensedConsolidatedBalanceSheetsParenthetical Condensed Consolidated Balance Sheets (Parenthetical) Statements 5 false false R6.htm 9952155 - Statement - Condensed Consolidated Statements of Stockholder's Equity Sheet http://www.ul.com/role/CondensedConsolidatedStatementsofStockholdersEquity Condensed Consolidated Statements of Stockholder's Equity Statements 6 false false R7.htm 9952156 - Statement - Condensed Consolidated Statements of Stockholder's Equity (Parenthetical) Sheet http://www.ul.com/role/CondensedConsolidatedStatementsofStockholdersEquityParenthetical Condensed Consolidated Statements of Stockholder's Equity (Parenthetical) Statements 7 false false R8.htm 9952157 - Statement - Condensed Consolidated Statements of Cash Flows Sheet http://www.ul.com/role/CondensedConsolidatedStatementsofCashFlows Condensed Consolidated Statements of Cash Flows Statements 8 false false R9.htm 9952158 - Disclosure - Significant Accounting Policies Sheet http://www.ul.com/role/SignificantAccountingPolicies Significant Accounting Policies Notes 9 false false R10.htm 9952159 - Disclosure - Earnings Per Share Sheet http://www.ul.com/role/EarningsPerShare Earnings Per Share Notes 10 false false R11.htm 9952160 - Disclosure - Revenue Sheet http://www.ul.com/role/Revenue Revenue Notes 11 false false R12.htm 9952161 - Disclosure - Divestiture Sheet http://www.ul.com/role/Divestiture Divestiture Notes 12 false false R13.htm 9952162 - Disclosure - Other Expense, net Sheet http://www.ul.com/role/OtherExpensenet Other Expense, net Notes 13 false false R14.htm 9952163 - Disclosure - Fair Value of Financial Instruments Sheet http://www.ul.com/role/FairValueofFinancialInstruments Fair Value of Financial Instruments Notes 14 false false R15.htm 9952164 - Disclosure - Investments in Equity Securities Sheet http://www.ul.com/role/InvestmentsinEquitySecurities Investments in Equity Securities Notes 15 false false R16.htm 9952165 - Disclosure - Goodwill Sheet http://www.ul.com/role/Goodwill Goodwill Notes 16 false false R17.htm 9952166 - Disclosure - Intangible Assets Sheet http://www.ul.com/role/IntangibleAssets Intangible Assets Notes 17 false false R18.htm 9952167 - Disclosure - Pension Sheet http://www.ul.com/role/Pension Pension Notes 18 false false R19.htm 9952168 - Disclosure - Income Taxes Sheet http://www.ul.com/role/IncomeTaxes Income Taxes Notes 19 false false R20.htm 9952169 - Disclosure - Long-Term Debt Sheet http://www.ul.com/role/LongTermDebt Long-Term Debt Notes 20 false false R21.htm 9952170 - Disclosure - Accumulated Other Comprehensive Loss Sheet http://www.ul.com/role/AccumulatedOtherComprehensiveLoss Accumulated Other Comprehensive Loss Notes 21 false false R22.htm 9952171 - Disclosure - Stock-based Compensation Sheet http://www.ul.com/role/StockbasedCompensation Stock-based Compensation Notes 22 false false R23.htm 9952172 - Disclosure - Restructuring Sheet http://www.ul.com/role/Restructuring Restructuring Notes 23 false false R24.htm 9952173 - Disclosure - Commitment and Contingencies Sheet http://www.ul.com/role/CommitmentandContingencies Commitment and Contingencies Notes 24 false false R25.htm 9952174 - Disclosure - Related Party Transactions Sheet http://www.ul.com/role/RelatedPartyTransactions Related Party Transactions Notes 25 false false R26.htm 9952175 - Disclosure - Segment Information Sheet http://www.ul.com/role/SegmentInformation Segment Information Notes 26 false false R27.htm 9952176 - Disclosure - Subsequent Events Sheet http://www.ul.com/role/SubsequentEvents Subsequent Events Notes 27 false false R28.htm 995445 - Disclosure - Insider Trading Arrangements Sheet http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements Insider Trading Arrangements Notes 28 false false R29.htm 9955511 - Disclosure - Significant Accounting Policies (Policies) Sheet http://www.ul.com/role/SignificantAccountingPoliciesPolicies Significant Accounting Policies (Policies) Policies http://www.ul.com/role/SignificantAccountingPolicies 29 false false R30.htm 9955512 - Disclosure - Earnings Per Share (Tables) Sheet http://www.ul.com/role/EarningsPerShareTables Earnings Per Share (Tables) Tables http://www.ul.com/role/EarningsPerShare 30 false false R31.htm 9955513 - Disclosure - Revenue (Tables) Sheet http://www.ul.com/role/RevenueTables Revenue (Tables) Tables http://www.ul.com/role/Revenue 31 false false R32.htm 9955514 - Disclosure - Divestiture (Tables) Sheet http://www.ul.com/role/DivestitureTables Divestiture (Tables) Tables http://www.ul.com/role/Divestiture 32 false false R33.htm 9955515 - Disclosure - Other Expense, net (Tables) Sheet http://www.ul.com/role/OtherExpensenetTables Other Expense, net (Tables) Tables http://www.ul.com/role/OtherExpensenet 33 false false R34.htm 9955516 - Disclosure - Fair Value of Financial Instruments (Tables) Sheet http://www.ul.com/role/FairValueofFinancialInstrumentsTables Fair Value of Financial Instruments (Tables) Tables http://www.ul.com/role/FairValueofFinancialInstruments 34 false false R35.htm 9955517 - Disclosure - Goodwill (Tables) Sheet http://www.ul.com/role/GoodwillTables Goodwill (Tables) Tables http://www.ul.com/role/Goodwill 35 false false R36.htm 9955518 - Disclosure - Intangible Assets (Tables) Sheet http://www.ul.com/role/IntangibleAssetsTables Intangible Assets (Tables) Tables http://www.ul.com/role/IntangibleAssets 36 false false R37.htm 9955519 - Disclosure - Pension (Tables) Sheet http://www.ul.com/role/PensionTables Pension (Tables) Tables http://www.ul.com/role/Pension 37 false false R38.htm 9955520 - Disclosure - Long-Term Debt (Tables) Sheet http://www.ul.com/role/LongTermDebtTables Long-Term Debt (Tables) Tables http://www.ul.com/role/LongTermDebt 38 false false R39.htm 9955521 - Disclosure - Accumulated Other Comprehensive Loss (Tables) Sheet http://www.ul.com/role/AccumulatedOtherComprehensiveLossTables Accumulated Other Comprehensive Loss (Tables) Tables http://www.ul.com/role/AccumulatedOtherComprehensiveLoss 39 false false R40.htm 9955522 - Disclosure - Stock-based Compensation (Tables) Sheet http://www.ul.com/role/StockbasedCompensationTables Stock-based Compensation (Tables) Tables http://www.ul.com/role/StockbasedCompensation 40 false false R41.htm 9955523 - Disclosure - Restructuring (Tables) Sheet http://www.ul.com/role/RestructuringTables Restructuring (Tables) Tables http://www.ul.com/role/Restructuring 41 false false R42.htm 9955524 - Disclosure - Segment Information (Tables) Sheet http://www.ul.com/role/SegmentInformationTables Segment Information (Tables) Tables http://www.ul.com/role/SegmentInformation 42 false false R43.htm 9955525 - Disclosure - Earnings Per Share (Details) Sheet http://www.ul.com/role/EarningsPerShareDetails Earnings Per Share (Details) Details http://www.ul.com/role/EarningsPerShareTables 43 false false R44.htm 9955526 - Disclosure - Revenue - Major Service Categories (Details) Sheet http://www.ul.com/role/RevenueMajorServiceCategoriesDetails Revenue - Major Service Categories (Details) Details 44 false false R45.htm 9955527 - Disclosure - Revenue - Narrative (Details) Sheet http://www.ul.com/role/RevenueNarrativeDetails Revenue - Narrative (Details) Details 45 false false R46.htm 9955528 - Disclosure - Divestiture - Narrative (Details) Sheet http://www.ul.com/role/DivestitureNarrativeDetails Divestiture - Narrative (Details) Details 46 false false R47.htm 9955529 - Disclosure - Divestiture - Schedule of Assets and Liabilities Held for Sale (Details) Sheet http://www.ul.com/role/DivestitureScheduleofAssetsandLiabilitiesHeldforSaleDetails Divestiture - Schedule of Assets and Liabilities Held for Sale (Details) Details 47 false false R48.htm 9955530 - Disclosure - Other Expense, net (Details) Sheet http://www.ul.com/role/OtherExpensenetDetails Other Expense, net (Details) Details http://www.ul.com/role/OtherExpensenetTables 48 false false R49.htm 9955531 - Disclosure - Fair Value of Financial Instruments (Details) Sheet http://www.ul.com/role/FairValueofFinancialInstrumentsDetails Fair Value of Financial Instruments (Details) Details http://www.ul.com/role/FairValueofFinancialInstrumentsTables 49 false false R50.htm 9955532 - Disclosure - Investments in Equity Securities (Details) Sheet http://www.ul.com/role/InvestmentsinEquitySecuritiesDetails Investments in Equity Securities (Details) Details http://www.ul.com/role/InvestmentsinEquitySecurities 50 false false R51.htm 9955533 - Disclosure - Goodwill (Details) Sheet http://www.ul.com/role/GoodwillDetails Goodwill (Details) Details http://www.ul.com/role/GoodwillTables 51 false false R52.htm 9955534 - Disclosure - Intangible Assets (Details) Sheet http://www.ul.com/role/IntangibleAssetsDetails Intangible Assets (Details) Details http://www.ul.com/role/IntangibleAssetsTables 52 false false R53.htm 9955535 - Disclosure - Pension - Defined Benefit Plan (Details) Sheet http://www.ul.com/role/PensionDefinedBenefitPlanDetails Pension - Defined Benefit Plan (Details) Details 53 false false R54.htm 9955536 - Disclosure - Pension - Defined Contribution Plan (Details) Sheet http://www.ul.com/role/PensionDefinedContributionPlanDetails Pension - Defined Contribution Plan (Details) Details 54 false false R55.htm 9955537 - Disclosure - Income Taxes (Details) Sheet http://www.ul.com/role/IncomeTaxesDetails Income Taxes (Details) Details http://www.ul.com/role/IncomeTaxes 55 false false R56.htm 9955538 - Disclosure - Long-Term Debt - Outstanding Debt (Details) Sheet http://www.ul.com/role/LongTermDebtOutstandingDebtDetails Long-Term Debt - Outstanding Debt (Details) Details 56 false false R57.htm 9955539 - Disclosure - Long-Term Debt - Narrative (Details) Sheet http://www.ul.com/role/LongTermDebtNarrativeDetails Long-Term Debt - Narrative (Details) Details 57 false false R58.htm 9955540 - Disclosure - Accumulated Other Comprehensive Loss (Details) Sheet http://www.ul.com/role/AccumulatedOtherComprehensiveLossDetails Accumulated Other Comprehensive Loss (Details) Details http://www.ul.com/role/AccumulatedOtherComprehensiveLossTables 58 false false R59.htm 9955541 - Disclosure - Stock-based Compensation - Compensation Expense (Details) Sheet http://www.ul.com/role/StockbasedCompensationCompensationExpenseDetails Stock-based Compensation - Compensation Expense (Details) Details 59 false false R60.htm 9955542 - Disclosure - Restructuring - Narrative (Details) Sheet http://www.ul.com/role/RestructuringNarrativeDetails Restructuring - Narrative (Details) Details 60 false false R61.htm 9955543 - Disclosure - Restructuring - Summary of Restructuring Charges (Details) Sheet http://www.ul.com/role/RestructuringSummaryofRestructuringChargesDetails Restructuring - Summary of Restructuring Charges (Details) Details 61 false false R62.htm 9955544 - Disclosure - Restructuring - Changes in Accrued Restructuring Balance (Details) Sheet http://www.ul.com/role/RestructuringChangesinAccruedRestructuringBalanceDetails Restructuring - Changes in Accrued Restructuring Balance (Details) Details 62 false false R63.htm 9955545 - Disclosure - Related Party Transactions (Details) Sheet http://www.ul.com/role/RelatedPartyTransactionsDetails Related Party Transactions (Details) Details http://www.ul.com/role/RelatedPartyTransactions 63 false false R64.htm 9955546 - Disclosure - Segment Information - Narrative (Details) Sheet http://www.ul.com/role/SegmentInformationNarrativeDetails Segment Information - Narrative (Details) Details 64 false false R65.htm 9955547 - Disclosure - Segment Information - Schedule Of Segment Expenses And Operating Income (Details) Sheet http://www.ul.com/role/SegmentInformationScheduleOfSegmentExpensesAndOperatingIncomeDetails Segment Information - Schedule Of Segment Expenses And Operating Income (Details) Details 65 false false R66.htm 9955548 - Disclosure - Subsequent Events (Details) Sheet http://www.ul.com/role/SubsequentEventsDetails Subsequent Events (Details) Details http://www.ul.com/role/SubsequentEvents 66 false false All Reports Book All Reports uls-20260331.htm uls-20260331.xsd uls-20260331_cal.xml uls-20260331_def.xml uls-20260331_lab.xml uls-20260331_pre.xml http://fasb.org/us-gaap/2025 http://xbrl.sec.gov/dei/2025 http://xbrl.sec.gov/ecd/2025 true true