3.26.1 html 274 396 1 true 74 0 false 8 false false R1.htm 75000 - Document - Document and Entity Information Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DocumentDocumentAndEntityInformation Document and Entity Information Cover 1 false false R2.htm 75010 - Statement - Consolidated Balance Sheets (Unaudited) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_StatementConsolidatedBalanceSheetsUnaudited Consolidated Balance Sheets (Unaudited) Statements 2 false false R3.htm 75020 - Statement - Consolidated Balance Sheets (Parenthetical) (Unaudited) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_StatementConsolidatedBalanceSheetsParentheticalUnaudited Consolidated Balance Sheets (Parenthetical) (Unaudited) Statements 3 false false R4.htm 75030 - Statement - Consolidated Statements of Income (Unaudited) Sheet http://www.parsons.com/20260331/taxonomy/role/StatementConsolidatedStatementsOfIncomeUnaudited Consolidated Statements of Income (Unaudited) Statements 4 false false R5.htm 75040 - Statement - Consolidated Statements of Comprehensive Income (Unaudited) Sheet http://www.parsons.com/20260331/taxonomy/role/StatementConsolidatedStatementsOfComprehensiveIncomeUnaudited Consolidated Statements of Comprehensive Income (Unaudited) Statements 5 false false R6.htm 75050 - Statement - Consolidated Statements of Cash Flows (Unaudited) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_StatementConsolidatedStatementsOfCashFlowsUnaudited Consolidated Statements of Cash Flows (Unaudited) Statements 6 false false R7.htm 75060 - Statement - Consolidated Statements of Shareholders' Equity (Unaudited) Sheet http://www.parsons.com/20260331/taxonomy/role/StatementConsolidatedStatementsOfShareholdersEquityUnaudited Consolidated Statements of Shareholders' Equity (Unaudited) Statements 7 false false R8.htm 995410 - Disclosure - Pay vs Performance Disclosure Sheet http://xbrl.sec.gov/ecd/role/PvpDisclosure Pay vs Performance Disclosure Notes 8 false false R9.htm 995445 - Disclosure - Insider Trading Arrangements Sheet http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements Insider Trading Arrangements Notes 9 false false R10.htm 995457 - Disclosure - Description of Operations Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureDescriptionOfOperations Description of Operations Notes 10 false false R11.htm 995467 - Disclosure - Basis of Presentation and Principles of Consolidation Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureBasisOfPresentationAndPrinciplesOfConsolidation Basis of Presentation and Principles of Consolidation Notes 11 false false R12.htm 995477 - Disclosure - New Accounting Pronouncements Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureNewAccountingPronouncements New Accounting Pronouncements Notes 12 false false R13.htm 995487 - Disclosure - Acquisitions Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureAcquisitions Acquisitions Notes 13 false false R14.htm 995497 - Disclosure - Contracts with Customers Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureContractsWithCustomers Contracts with Customers Notes 14 false false R15.htm 995507 - Disclosure - Leases Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureLeases Leases Notes 15 false false R16.htm 995517 - Disclosure - Goodwill Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureGoodwill Goodwill Notes 16 false false R17.htm 995527 - Disclosure - Intangible Assets Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureIntangibleAssets Intangible Assets Notes 17 false false R18.htm 995537 - Disclosure - Property and Equipment, Net Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosurePropertyAndEquipmentNet Property and Equipment, Net Notes 18 false false R19.htm 995547 - Disclosure - Debt and Credit Facilities Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureDebtAndCreditFacilities Debt and Credit Facilities Notes 19 false false R20.htm 995557 - Disclosure - Income Taxes Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureIncomeTaxes Income Taxes Notes 20 false false R21.htm 995567 - Disclosure - Contingencies Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureContingencies Contingencies Notes 21 false false R22.htm 995577 - Disclosure - Retirement Benefit Plan Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureRetirementBenefitPlan Retirement Benefit Plan Notes 22 false false R23.htm 995587 - Disclosure - Investments in and Advances to Joint Ventures Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureInvestmentsInAndAdvancesToJointVentures Investments in and Advances to Joint Ventures Notes 23 false false R24.htm 995597 - Disclosure - Related Party Transactions Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureRelatedPartyTransactions Related Party Transactions Notes 24 false false R25.htm 995607 - Disclosure - Fair Value of Financial Instruments Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureFairValueOfFinancialInstruments Fair Value of Financial Instruments Notes 25 false false R26.htm 995617 - Disclosure - Earnings Per Share Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureEarningsPerShare Earnings Per Share Notes 26 false false R27.htm 995627 - Disclosure - Segment Information Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureSegmentInformation Segment Information Notes 27 false false R28.htm 995637 - Disclosure - Subsequent Events Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureSubsequentEvents Subsequent Events Notes 28 false false R29.htm 995647 - Disclosure - Basis of Presentation and Principles of Consolidation (Policies) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureBasisOfPresentationAndPrinciplesOfConsolidationPolicies Basis of Presentation and Principles of Consolidation (Policies) Policies http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureNewAccountingPronouncements 29 false false R30.htm 995657 - Disclosure - Acquisitions (Tables) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureAcquisitionsTables Acquisitions (Tables) Tables http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureAcquisitions 30 false false R31.htm 995667 - Disclosure - Contracts with Customers (Tables) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureContractsWithCustomersTables Contracts with Customers (Tables) Tables http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureContractsWithCustomers 31 false false R32.htm 995677 - Disclosure - Leases (Tables) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureLeasesTables Leases (Tables) Tables http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureLeases 32 false false R33.htm 995687 - Disclosure - Goodwill (Tables) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureGoodwillTables Goodwill (Tables) Tables http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureGoodwill 33 false false R34.htm 995697 - Disclosure - Intangible Assets (Tables) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureIntangibleAssetsTables Intangible Assets (Tables) Tables http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureIntangibleAssets 34 false false R35.htm 995707 - Disclosure - Property and Equipment, Net (Tables) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosurePropertyAndEquipmentNetTables Property and Equipment, Net (Tables) Tables http://www.parsons.com/20260331/taxonomy/role/Role_DisclosurePropertyAndEquipmentNet 35 false false R36.htm 995717 - Disclosure - Debt and Credit Facilities (Tables) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureDebtAndCreditFacilitiesTables Debt and Credit Facilities (Tables) Tables http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureDebtAndCreditFacilities 36 false false R37.htm 995727 - Disclosure - Investments in and Advances to Joint Ventures (Tables) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureInvestmentsInAndAdvancesToJointVenturesTables Investments in and Advances to Joint Ventures (Tables) Tables http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureInvestmentsInAndAdvancesToJointVentures 37 false false R38.htm 995737 - Disclosure - Related Party Transactions (Tables) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureRelatedPartyTransactionsTables Related Party Transactions (Tables) Tables http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureRelatedPartyTransactions 38 false false R39.htm 995747 - Disclosure - Fair Value of Financial Instruments (Tables) Sheet http://www.parsons.com/20260331/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsTables Fair Value of Financial Instruments (Tables) Tables http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureFairValueOfFinancialInstruments 39 false false R40.htm 995757 - Disclosure - Earnings Per Share (Tables) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureEarningsPerShareTables Earnings Per Share (Tables) Tables http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureEarningsPerShare 40 false false R41.htm 995767 - Disclosure - Segment Information (Tables) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureSegmentInformationTables Segment Information (Tables) Tables http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureSegmentInformation 41 false false R42.htm 995787 - Disclosure - New Accounting Pronouncements - Additional Information (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureNewAccountingPronouncementsAdditionalInformationDetails New Accounting Pronouncements - Additional Information (Details) Details 42 false false R43.htm 995797 - Disclosure - Acquisitions - Additional Information (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureAcquisitionsAdditionalInformationDetails Acquisitions - Additional Information (Details) Details 43 false false R44.htm 995807 - Disclosure - Acquisitions - Summary of Acquisition Date FAir Value of Purchase Consideration Transferred (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/DisclosureAcquisitionsSummaryOfAcquisitionDateFairValueOfPurchaseConsiderationTransferredDetails Acquisitions - Summary of Acquisition Date FAir Value of Purchase Consideration Transferred (Details) Details 44 false false R45.htm 995817 - Disclosure - Acquisitions - Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed on Preliminary Purchase Price Allocation (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/DisclosureAcquisitionsSummaryOfEstimatedFairValuesOfAssetsAcquiredAndLiabilitiesAssumedOnPreliminaryPurchasePriceAllocationDetails Acquisitions - Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed on Preliminary Purchase Price Allocation (Details) Details 45 false false R46.htm 995827 - Disclosure - Acquisitions - Schedule of Intangible Assets Value on Purchase Price (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureAcquisitionsScheduleOfIntangibleAssetsValueOnPurchasePriceDetails Acquisitions - Schedule of Intangible Assets Value on Purchase Price (Details) Details 46 false false R47.htm 995837 - Disclosure - Acquisitions - Schedule of Supplemental Pro Forma Information (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureAcquisitionsScheduleOfSupplementalProFormaInformationDetails Acquisitions - Schedule of Supplemental Pro Forma Information (Details) Details 47 false false R48.htm 995847 - Disclosure - Contracts with Customers - Summary of Disaggregation of Revenue (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureContractsWithCustomersSummaryOfDisaggregationOfRevenueDetails Contracts with Customers - Summary of Disaggregation of Revenue (Details) Details 48 false false R49.htm 995857 - Disclosure - Contracts with Customers - Summary of Contract Assets and Contract Liabilities (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureContractsWithCustomersSummaryOfContractAssetsAndContractLiabilitiesDetails Contracts with Customers - Summary of Contract Assets and Contract Liabilities (Details) Details 49 false false R50.htm 995877 - Disclosure - Contracts with Customers - Summary of Contract Assets and Contract Liabilities (Parenthetical) (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureContractsWithCustomersSummaryOfContractAssetsAndContractLiabilitiesParentheticalDetails Contracts with Customers - Summary of Contract Assets and Contract Liabilities (Parenthetical) (Details) Details 50 false false R51.htm 995887 - Disclosure - Contracts with Customers - Summary of Changes in Contract Assets and Contract Liabilities (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureContractsWithCustomersSummaryOfChangesInContractAssetsAndContractLiabilitiesDetails Contracts with Customers - Summary of Changes in Contract Assets and Contract Liabilities (Details) Details 51 false false R52.htm 995897 - Disclosure - Contracts with Customers - Additional Information (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/DisclosureContractsWithCustomersAdditionalInformationDetails Contracts with Customers - Additional Information (Details) Details 52 false false R53.htm 995907 - Disclosure - Contracts with Customers - Summary of Accounts Receivable, Net (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureContractsWithCustomersSummaryOfAccountsReceivableNetDetails Contracts with Customers - Summary of Accounts Receivable, Net (Details) Details 53 false false R54.htm 995917 - Disclosure - Contracts with Customers - Summary of Remaining Unsatisfied Performance Obligations Expect to Satisfy (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureContractsWithCustomersSummaryOfRemainingUnsatisfiedPerformanceObligationsExpectToSatisfyDetails Contracts with Customers - Summary of Remaining Unsatisfied Performance Obligations Expect to Satisfy (Details) Details 54 false false R55.htm 995927 - Disclosure - Leases - Additional Information (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureLeasesAdditionalInformationDetails Leases - Additional Information (Details) Details 55 false false R56.htm 995937 - Disclosure - Leases - Summary of Lease Costs (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureLeasesSummaryOfLeaseCostsDetails Leases - Summary of Lease Costs (Details) Details 56 false false R57.htm 995947 - Disclosure - Leases - Schedule of Supplemental Cash Flow Information Related to Leases (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureLeasesScheduleOfSupplementalCashFlowInformationRelatedToLeasesDetails Leases - Schedule of Supplemental Cash Flow Information Related to Leases (Details) Details 57 false false R58.htm 995957 - Disclosure - Leases - Schedule of Supplemental Balance Sheet and Other Information Related to Leases (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureLeasesScheduleOfSupplementalBalanceSheetAndOtherInformationRelatedToLeasesDetails Leases - Schedule of Supplemental Balance Sheet and Other Information Related to Leases (Details) Details 58 false false R59.htm 995967 - Disclosure - Leases - Schedule of Maturity Analysis of Future Undiscounted Cash Flows (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureLeasesScheduleOfMaturityAnalysisOfFutureUndiscountedCashFlowsDetails Leases - Schedule of Maturity Analysis of Future Undiscounted Cash Flows (Details) Details 59 false false R60.htm 995987 - Disclosure - Goodwill - Summary of Changes in Carrying Value of Goodwill by Reporting Segment (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureGoodwillSummaryOfChangesInCarryingValueOfGoodwillByReportingSegmentDetails Goodwill - Summary of Changes in Carrying Value of Goodwill by Reporting Segment (Details) Details 60 false false R61.htm 995997 - Disclosure - Goodwill - Additional Information (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureGoodwillAdditionalInformationDetails Goodwill - Additional Information (Details) Details 61 false false R62.htm 996007 - Disclosure - Intangible Assets - Schedule of Gross Amount and Accumulated Amortization of Intangible Assets (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureIntangibleAssetsScheduleOfGrossAmountAndAccumulatedAmortizationOfIntangibleAssetsDetails Intangible Assets - Schedule of Gross Amount and Accumulated Amortization of Intangible Assets (Details) Details 62 false false R63.htm 996017 - Disclosure - Intangible Assets - Additional Information (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureIntangibleAssetsAdditionalInformationDetails Intangible Assets - Additional Information (Details) Details 63 false false R64.htm 996027 - Disclosure - Intangible Assets - Schedule of Estimated Amortization Expense (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureIntangibleAssetsScheduleOfEstimatedAmortizationExpenseDetails Intangible Assets - Schedule of Estimated Amortization Expense (Details) Details 64 false false R65.htm 996037 - Disclosure - Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosurePropertyAndEquipmentNetScheduleOfPropertyAndEquipmentNetDetails Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) Details 65 false false R66.htm 996047 - Disclosure - Property and Equipment, Net - Additional Information (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosurePropertyAndEquipmentNetAdditionalInformationDetails Property and Equipment, Net - Additional Information (Details) Details 66 false false R67.htm 996057 - Disclosure - Debt and Credit Facilities - Schedule of Debt (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureDebtAndCreditFacilitiesScheduleOfDebtDetails Debt and Credit Facilities - Schedule of Debt (Details) Details 67 false false R68.htm 996067 - Disclosure - Debt and Credit Facilities - Additional Information (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureDebtAndCreditFacilitiesAdditionalInformationDetails Debt and Credit Facilities - Additional Information (Details) Details 68 false false R69.htm 996077 - Disclosure - Income Taxes - Additional Information (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureIncomeTaxesAdditionalInformationDetails Income Taxes - Additional Information (Details) Details 69 false false R70.htm 996087 - Disclosure - Contingencies - Additional Information (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureContingenciesAdditionalInformationDetails Contingencies - Additional Information (Details) Details 70 false false R71.htm 996097 - Disclosure - Retirement Benefit Plan - Additional Information (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureRetirementBenefitPlanAdditionalInformationDetails Retirement Benefit Plan - Additional Information (Details) Details 71 false false R72.htm 996107 - Disclosure - Investments in and Advances to Joint Ventures - Additional Information (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureInvestmentsInAndAdvancesToJointVenturesAdditionalInformationDetails Investments in and Advances to Joint Ventures - Additional Information (Details) Details 72 false false R73.htm 996117 - Disclosure - Investments in and Advances to Joint Ventures - Summary of Financial Information for Consolidated Joint Ventures (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureInvestmentsInAndAdvancesToJointVenturesSummaryOfFinancialInformationForConsolidatedJointVenturesDetails Investments in and Advances to Joint Ventures - Summary of Financial Information for Consolidated Joint Ventures (Details) Details 73 false false R74.htm 996127 - Disclosure - Investments in and Advances to Joint Ventures - Summary of Financial Information for Unconsolidated Joint Ventures (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureInvestmentsInAndAdvancesToJointVenturesSummaryOfFinancialInformationForUnconsolidatedJointVenturesDetails Investments in and Advances to Joint Ventures - Summary of Financial Information for Unconsolidated Joint Ventures (Details) Details 74 false false R75.htm 996137 - Disclosure - Related Party Transactions - Additional Information (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails Related Party Transactions - Additional Information (Details) Details 75 false false R76.htm 996147 - Disclosure - Related Party Transactions - Schedule of Consolidated Balance Sheet Related to Services Provided to Unconsolidated Joint Ventures (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureRelatedPartyTransactionsScheduleOfConsolidatedBalanceSheetRelatedToServicesProvidedToUnconsolidatedJointVenturesDetails Related Party Transactions - Schedule of Consolidated Balance Sheet Related to Services Provided to Unconsolidated Joint Ventures (Details) Details 76 false false R77.htm 996157 - Disclosure - Fair Value of Financial Instruments - Summary of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsSummaryOfFinancialAssetsAndLiabilitiesMeasuredAtFairValueOnARecurringBasisDetails Fair Value of Financial Instruments - Summary of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) Details 77 false false R78.htm 996167 - Disclosure - Fair Value of Financial Instruments - Summary of Carrying Values and Estimated Fair Values Of Financial Instruments (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsSummaryOfCarryingValuesAndEstimatedFairValuesOfFinancialInstrumentsDetails Fair Value of Financial Instruments - Summary of Carrying Values and Estimated Fair Values Of Financial Instruments (Details) Details 78 false false R79.htm 996177 - Disclosure - Earnings Per Share - Additional Information (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureEarningsPerShareAdditionalInformationDetails Earnings Per Share - Additional Information (Details) Details 79 false false R80.htm 996187 - Disclosure - Earnings Per Share - Schedule of Denominator and Numerator used to Compute Basic and Diluted EPS (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/DisclosureEarningsPerShareScheduleOfDenominatorAndNumeratorUsedToComputeBasicAndDilutedEpsDetails Earnings Per Share - Schedule of Denominator and Numerator used to Compute Basic and Diluted EPS (Details) Details 80 false false R81.htm 996197 - Disclosure - Earnings Per Share - Schedule of Repurchase Program (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureEarningsPerShareScheduleOfRepurchaseProgramDetails Earnings Per Share - Schedule of Repurchase Program (Details) Details 81 false false R82.htm 996207 - Disclosure - Segment Information - Additional Information (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureSegmentInformationAdditionalInformationDetails Segment Information - Additional Information (Details) Details 82 false false R83.htm 996217 - Disclosure - Segment Information - Summary of Adjusted EBITDA Business Segment Information (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureSegmentInformationSummaryOfAdjustedEBITDABusinessSegmentInformationDetails Segment Information - Summary of Adjusted EBITDA Business Segment Information (Details) Details 83 false false R84.htm 996227 - Disclosure - Segment Information - Summary of Revenues and Property and Equipment, Net by Geographic Area (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureSegmentInformationSummaryOfRevenuesAndPropertyAndEquipmentNetByGeographicAreaDetails Segment Information - Summary of Revenues and Property and Equipment, Net by Geographic Area (Details) Details 84 false false R85.htm 996237 - Disclosure - Segment Information - Summary of Revenues by Business Lines (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureSegmentInformationSummaryOfRevenuesByBusinessLinesDetails Segment Information - Summary of Revenues by Business Lines (Details) Details 85 false false R86.htm 996247 - Disclosure - Subsequent Events - Additional Information (Details) Sheet http://www.parsons.com/20260331/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails Subsequent Events - Additional Information (Details) Details 86 false false All Reports Book All Reports psn-20260331.htm psn-20260331.xsd img234374104_0.gif img234374104_1.jpg http://fasb.org/srt/2025 http://fasb.org/us-gaap/2025 http://xbrl.sec.gov/dei/2025 http://xbrl.sec.gov/ecd/2025 false false