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Date Operating lease right-of-use assets Business Combination, Recognized Liability Assumed, Operating Lease Right-of-Use Assets Business Combination, Recognized Liability Assumed, Operating Lease Right-of-Use Assets Proceeds from issuances of stock Proceeds from Issuance or Sale of Equity Stated interest rate Debt interest rate (as percent) Debt Instrument, Interest Rate, Stated Percentage Counterparty Name [Domain] Counterparty Name [Domain] Total Leidos stockholders’ equity Equity, Attributable to Parent Covenant, consolidated EBITDA to interest expense ratio Debt Instrument, Covenant, Consolidated EBITDA To Interest Expense Ratio Debt Instrument, Covenant, Consolidated EBITDA To Interest Expense Ratio 2028 Other Commitment, to be Paid, Year Two Number of markets served Number Of Markets Served Number Of Markets Served Defense Defense Segment [Member] Defense Segment Assets: Assets [Abstract] Title Trading Arrangement, Individual Title Forgone Recovery due to Disqualification of Tax 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Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect, Discontinued Operation Underlying Securities Award Underlying Securities Amount Less: net income attributable to non-‍controlling interest Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Estimate of fair value measurement Estimate of Fair Value Measurement [Member] Revenues Revenue from Contract with Customer [Text Block] Issuances of stock Stock Issued During Period, Value, New Issues Estimated Annual Intangible Amortization Expense Intangible Asset, Finite-Lived, and Capitalized Cost, Software to be Sold, Leased, or Marketed, Estimated Amortization Expense [Abstract] Other Payment for (Proceeds from) Other Investing Activity Net capital distributions to non-controlling interests Proceeds from (Payments to) Noncontrolling Interests Segment Reporting [Table] Segment Reporting [Table] Intelligence & Digital Intelligence and Digital Segment [Member] Intelligence and Digital Segment Other current assets Other Assets, Current Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] All Trading Arrangements All Trading Arrangements [Member] Other Performance Measure, Amount Other Performance Measure, Amount Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Operating income Operating Income (Loss) $250 million notes, due July 2032 Notes Which Mature On July Two Thousand Thirty Two [Member] Notes Which Mature On July Two Thousand Thirty Two [Member] Changes in Estimates on Contracts Changes In Estimates On Contracts [Policy Text Block] Changes In Estimates On Contracts [Policy Text Block] Remaining performance obligations, which are expected to be recognized as revenue Revenue, Remaining Performance Obligation, Amount Leidos, Inc. 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Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Accounts payable and accrued liabilities Accounts Payable and Accrued Liabilities, Current Entity Small Business Entity Small Business Comprehensive income attributable to Leidos common stockholders Comprehensive Income (Loss), Net of Tax, Attributable to Parent Schedule of Guaranteed Obligation by Fiscal Year Maturity Guaranteed Obligation, Fiscal Year Maturity [Table Text Block] Guaranteed Obligation, Fiscal Year Maturity Termination Date Trading Arrangement Termination Date Other Commitments [Axis] Other Commitments [Axis] Weighted Amortization Period Intangible Asset, Finite-Lived, Acquired, Weighted-Average Amortization Period Subsequent Events [Abstract] Subsequent Events [Abstract] Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Intangible assets Business Combination, Recognized Asset Acquired, Identifiable Intangible Asset, 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Cover [Abstract] International Non-US [Member] Foreign currency translation adjustments Goodwill, Foreign Currency Translation, Gain (Loss) Equity Awards Adjustments Equity Awards Adjustments [Member] Revenue, Initial Application Period Cumulative Effect Transition [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Total liabilities and stockholders' equity Liabilities and Equity Employee Stock Option Share-Based Payment Arrangement, Option [Member] Current portion of long-term debt Debt, Current Non-controlling interest Equity, Attributable to Noncontrolling Interest Segments [Axis] Segments [Axis] Segments [Axis] Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Tabular List, Table Tabular List [Table Text Block] Additional paid-in capital Additional Paid in Capital Homeland Homeland Segment [Member] Homeland Segment Other expense, net Corporate expense Other Nonoperating Income (Expense) Debt Long-Term Debt [Text 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Aggregate Erroneous Compensation Amount Cash paid for interest Interest Paid, Excluding Capitalized Interest, Operating Activity Payments for property, equipment and software Payments to Acquire Productive Assets Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Total Other Commitment Credit Facility [Axis] Credit Facility [Axis] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Long-term debt, net of current portion Total long-term debt, net of current portion Long-Term Debt and Lease Obligation Direct labor Cost, Direct Labor Name Measure Name Income Taxes Income Tax Disclosure [Text Block] Pay vs Performance Disclosure [Line Items] Other U.S. government agencies Other Government Agencies [Member] Other Government Agencies [Member] Other Other Noncash Income (Expense) Debt Instrument [Line Items] Debt Instrument [Line Items] Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Purchase consideration Business Combination, Consideration Transferred Additional paid-in capital Additional Paid-in Capital [Member] Entity Filer Category Entity Filer Category $500 million notes, due March 2035 Notes Which Mature On March Two Thousand Thirty Five [Member] Notes Which Mature On March Two Thousand Thirty Five Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] Goodwill impairment Goodwill, Impairment Loss Revenue recognized Revenue Not from Contract with Customer Name Trading Arrangement, Individual Name Cash and cash equivalents Cash and cash equivalents at end of period Cash and Cash Equivalent Net (decrease) increase in cash, cash equivalents and restricted cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect, Continuing Operation Company Selected Measure Amount Company Selected Measure Amount Depreciation and amortization Depreciation, Depletion and Amortization 2027 Other Commitment, to be Paid, Year One Number of employees in global workforce Entity Number of Employees Acquisition, integration and restructuring costs Acquisition, Integration and Restructuring Costs Acquisition, Integration and Restructuring Costs Net income Net income Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Revenues Business Combination, Pro Forma Information, Pro Forma Revenue Non-PEO NEO Non-PEO NEO [Member] Senior Notes Senior Notes [Member] Entity Address, Address Line One Entity Address, Address Line One Income tax expense Income Tax Expense (Benefit) Noncontrolling interest (as a percentage) Equity Method Investment, Noncontrolling Interest, Percentage Equity Method Investment, Noncontrolling Interest, Percentage Award Timing Method Award Timing Method [Text Block] Consolidation Consolidation, Policy [Policy Text Block] Net (decrease) increase in cash, cash equivalents and restricted cash, including cash classified in current assets held for sale Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Forecast Forecast [Member] Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Health Health Segment [Member] Health Segment [Member] Deferred tax liabilities Business Combination, Recognized Liability Assumed, Deferred Tax Liability Net income attributable to Leidos common stockholders Net Income (Loss) Attributable to Parent Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Bridge Loan Bridge Loan [Member] Goodwill Disposal Group, Including Discontinued Operation, Goodwill Statement [Table] Statement [Table] Restatement Determination Date: Restatement Determination Date [Axis] Schedule of Changes in the Components of Accumulated Other Comprehensive Income (Loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Transfers to assets held for sale Goodwill, Transfers Schedule of Components of Contract Assets and Contract Liabilities Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block] Receivables Increase (Decrease) in Receivables Schedule of Preliminary Fair Value of Intangible Assets Acquire Weighted Average Amortization Business Combination, Intangible Asset, Acquired, Indefinite-Lived [Table Text Block] Basis of Presentation and Summary of Significant Accounting Policies Basis of Presentation and Significant Accounting Policies [Text Block] Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block]