Entity tax identification number Entity Tax Identification Number Fair Value Investments at fair value EBP, Investment, Fair Value Employee rollovers EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Rollover Maximum Maximum [Member] Net change in participant loans deemed distributed EBP, Reconciliation to Form 5500, Change in Net Asset Available for Benefit, Increase (Decrease) from Deemed Distribution Legal Entity [Axis] Legal Entity [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] EBP, Description of Plan [Table] EBP, Description of Plan [Table] Mutual funds Mutual Fund [Member] Total Fully Corrected Under Voluntary Fiduciary Correction Program (VFCP) and Prohibited Transition Exemption 2002-51 EBP, Schedule of Delinquent Participant Contribution, Corrected Traditional Investment Contracts EBP, Traditional Guaranteed Investment Contract [Member] Pretax, maximum annual compensation to total compensation, percentage EBP, Participant Contribution, Pretax, Maximum Annual Compensation to Total Compensation, Percentage EBP, Fully Benefit-Responsive Investment Contract [Table] EBP, Fully Benefit-Responsive Investment Contract [Table] Self-directed brokerage fund EBP, Self-Directed Brokerage Account [Member] Total deductions EBP, Change in Net Asset Available for Benefit, Decrease Maximum borrowing, amount EBP, Note Receivable from Participant, Account, Maximum Borrowing, Amount Fair Value Measurements EBP, Investment, Fair Value and NAV [Text Block] Fees paid to recordkeeper EBP, Related Party And Party-In-Interest Transactions, Fees Paid To Recordkeeper EBP, Related Party And Party-In-Interest Transactions, Fees Paid To Recordkeeper EBP, Fully Benefit-Responsive Investment Contract [Abstract] Plan Interest EBP, Nonconsolidated, Plan Interest in Master Trust [Member] Level 1 Fair Value, Inputs, Level 1 [Member] EBP, Reconciliation of Financial Statement to Form 5500 EBP, Reconciliation of Financial Statement to Form 5500 [Table Text Block] Fully Benefit-Responsive Investment Contracts EBP, Fully Benefit-Responsive Investment Contract [Text Block] EBP, Investment, Fair Value and NAV [Abstract] Assets EBP, Asset [Abstract] Statistical Measurement [Axis] Statistical Measurement [Axis] ADDITIONS: EBP, Change in Net Asset Available for Benefit, Increase [Abstract] EBP, Statement of Change in Net Asset Available for Benefit [Table] EBP, Statement of Change in Net Asset Available for Benefit [Table] PLAN TO PLAN TRANSFER IN (NOTE 1) EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan EBP, Master Trust [Line Items] EBP, Master Trust [Line Items] Amendment Flag Amendment Flag Participant loans deemed distributed EBP, Reconciliation to Form 5500, Net Asset Available for Benefit, Deemed Distribution Basis of Accounting EBP, Basis of Accounting [Policy Text Block] Deemed loans repaid EBP, Reconciliation to Form 5500, Net Asset Available for Benefit, Deemed Loans Repaid EBP, Reconciliation to Form 5500, Net Asset Available for Benefit, Deemed Loans Repaid EBP, Schedule of Asset Held for Investment [Table] EBP, Schedule of Asset Held for Investment [Table] Total investments EBP, Investment, Plan Interest in Master Trust, Fair and Contract Value Note receivable liquidated EBP, Note Receivable, Liquidated EBP, Note Receivable, Liquidated Number of Shares (in shares) EBP, Investment, Number of Shares EBP, Description of Plan and Accounting Change [Abstract] Receivables: EBP, Receivable [Abstract] Fair Value Measurments EBP, Investment, Fair Value and NAV [Table Text Block] Summary of Common Stock Held by Master Trust EBP, Common Stock Held By Master Trust [Table Text Block] EBP, Common Stock Held By Master Trust Investments [Domain] Investments [Domain] EBP, Schedule of Delinquent Participant Contribution [Abstract] Receivable from plan merger (Note 1) EBP, Receivable From Plan Merger EBP, Receivable From Plan Merger EBP, Master Trust [Abstract] Investment in Leidos, Inc. Master Trust at contract value Total EBP, Investment, Plan Interest in Master Trust, Contract Value Separately managed account EBP, Pooled Separate Account [Member] Schedule H, Line 4i – Schedule of Assets (Held At End of Year) EBP, Schedule of Asset Held for Investment [Text Block] Cover [Abstract] EBP, Traditional And Synthetic Investment Contract EBP, Traditional And Synthetic Investment Contract [Member] EBP, Traditional And Synthetic Investment Contract Adjustment for change in plan merger assets not transferred at year end EBP, Reconciliation to Form 5500, Change in Net Asset Available for Benefit, Increase (Decrease) from Contract Value to Current Value Cost Basis EBP, Investment, Cost EBP, Investment, Cost Risks and Uncertainties EBP, Risk and Uncertainty [Text Block] Employer EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Cash EBP, Schedule of Delinquent Participant Contribution [Line Items] EBP, Schedule of Delinquent Participant Contribution [Line Items] Synthetic GICs EBP, Synthetic Investment Contract [Member] Minimum Minimum [Member] Investment Type [Axis] Investment Type [Axis] Interest income on notes receivable from participants EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Note Receivable from Participant Vesting percentage EBP, Employer Contribution Vesting Percentage Company contribution and/ or investment earning percentage vesting to the participant in Company Matching Contributions, Fixed Rate Contributions, Discretionary Profit-Sharing Contributions, Qualified Non-Elective Contributions, and Disability Contributions, upon completion of minimum service period or attainment of maximum vesting age Total contributions EBP, Change in Net Asset Available for Benefit, Increase from Contribution Participants EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Excluding Rollover Net appreciation in value of investments EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Gain (Loss) on Investment Interest income on notes receivable from participants EBP, Change in Net Asset Available for Benefit, Increase from Interest and Dividend Income on Investment EBP, Description of Plan [Line Items] EBP, Description of Plan [Line Items] Plan number EBP, Plan Number EBP, Investment, Fair Value and NAV [Line Items] EBP, Investment, Fair Value and NAV [Line Items] Description of the Plan EBP, Description of Plan [Text Block] Contributions Pending Correction in VFCP EBP, Schedule of Delinquent Participant Contribution, Pending Correction in VFCP EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Statement of Net Asset Available for Benefit [Table] EBP, Statement of Net Asset Available for Benefit [Table] EBP, Schedule of Asset Held for Investment [Line Items] EBP, Schedule of Asset Held for Investment [Line Items] EBP, Nonconsolidated, Master Trust and Plan Interest in Master Trust [Domain] EBP, Nonconsolidated, Master Trust and Plan Interest in Master Trust [Domain] Common stock Leidos Holdings, Inc. common stock EBP, Employer, Common Stock [Member] Adjustment for assets related to plan merger not yet transferred EBP, Reconciliation to Form 5500, Adjustment For Assets Related To Plan Merger Not Yet Transferred EBP, Reconciliation to Form 5500, Adjustment For Assets Related To Plan Merger Not Yet Transferred EBP, Schedule of Asset Held for Investment [Abstract] EBP, Accounting Policy [Table] EBP, Accounting Policy [Table] Total additions EBP, Change in Net Asset Available for Benefit, Increase Investment income: EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment [Abstract] Administrative expenses EBP, Change in Net Asset Available for Benefit, Decrease from Administrative Expense EBP, Asset Held for Investment EBP, Asset Held for Investment Cost Basis EBP, Investment, Contract Value Document Information [Line Items] Document Information [Line Items] Minimum vested balance eligible for distribution EBP, Distributions To Participants, Minimum Balance Required EBP, Distributions To Participants, Minimum Balance Required EBP 004 EBP 004 [Member] EBP 004 EBP, Risk and Uncertainty [Line Items] EBP, Risk and Uncertainty [Line Items] EBP, Risk and Uncertainty [Table] EBP, Risk and Uncertainty [Table] Plan’s Interest in Master Trust EBP, Master Trust [Text Block] Net change in deemed loans repaid EBP, Reconciliation to Form 5500, Change in Net Asset Available for Benefit, Increase (Decrease) From Deemed Loans Repaid EBP, Reconciliation to Form 5500, Change in Net Asset Available for Benefit, Increase (Decrease) From Deemed Loans Repaid Participant compensation matched, percentage EBP, Employer Contribution, Participant Compensation Matched, Percentage EBP, Statement of Change in Net Asset Available for Benefit [Abstract] Level 2 Fair Value, Inputs, Level 2 [Member] Maximum vested balance eligible for distribution EBP, Distributions To Participants, Maximum Balance Required EBP, Distributions To Participants, Maximum Balance Required Net income per Schedule H on Form 5500 EBP, Form 5500 Caption, Net Income (Loss) EBP, Fully Benefit-Responsive Investment Contract [Line Items] EBP, Fully Benefit-Responsive Investment Contract [Line Items] Contributions Corrected Outside VFCP EBP, Schedule of Delinquent Participant Contribution, Corrected Outside VFCP INCREASE IN NET ASSETS AVAILABLE FOR BENEFITS BEFORE TRANSFER EBP, Change in Net Asset Available for Benefit, Increase (Decrease) Total investments EBP, Investment, Fair and Contract Value EBP, Accounting Policy, Accounting Standard Update, and Change in Accounting Principle [Abstract] Total receivables EBP, Receivable Text Block [Abstract] Investments: EBP, Investment, Fair Value [Abstract] Benefits paid to participants EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant Investments at fair value EBP, Investment, Plan Interest in Master Trust, Fair Value Participant Contributions Transferred Late to the Plan (Participant Loan Repayments are Included) EBP, Schedule of Delinquent Participant Contribution, Transferred Late to Plan Involuntary cash-out limit EBP, Involuntary Cash-out Limit EBP, Involuntary Cash-out Limit Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] EBP, Statement of Net Asset Available for Benefit [Abstract] EBP, Accounting Policy [Line Items] EBP, Accounting Policy [Line Items] EBP, Reconciliation of Financial Statement to Form 5500 [Table] EBP, Reconciliation of Financial Statement to Form 5500 [Table] EBP, Fully Benefit-Responsive Investment Contract EBP, Fully Benefit-Responsive Investment Contract [Table Text Block] Net transfers out of Master Trust EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Change in Plan Interest in Master Trust Investments at fair value EBP, Investment, Plan Interest in Master Trust, Fair Value, Excluding Stable Value Fund EBP, Investment, Plan Interest in Master Trust, Fair Value, Excluding Stable Value Fund EBP, Reconciliation of Financial Statement to Form 5500 [Line Items] EBP, Reconciliation of Financial Statement to Form 5500 [Line Items] Administrative Expenses EBP, Expense [Policy Text Block] Reconciliation of Financial Statements to Form 5500 EBP, Reconciliation of Financial Statement to Form 5500 [Text Block] Participant loan, current value EBP, Asset Held for Investment, Participant Loan, after Deemed Distribution Investment Valuation and Income Recognition EBP, Investment [Policy Text Block] EBP, Master Trust [Table] EBP, Master Trust [Table] Fair Value, Inputs, Level 1, Level 2, and Level 3 Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] Document Type Document Type Entity Central Index Key Entity Central Index Key Participant loan, interest rate EBP, Asset Held for Investment, Participant Loan, Interest Rate EBP, Reconciliation of Financial Statement to Form 5500 [Abstract] Collective trusts Common Collective Trust [Member] EBP, Risk and Uncertainty [Abstract] DEDUCTIONS: EBP, Change in Net Asset Available for Benefit, Decrease [Abstract] Forfeited nonvested account, decrease from employer contribution EBP, Forfeited Nonvested Account, Decrease from Employer Contribution Notes receivable from participants EBP, Note Receivable from Participant Master Trust EBP, Nonconsolidated, Master Trust [Member] INCREASE IN NET ASSETS AVAILABLE FOR BENEFITS AFTER TRANSFER Increase in net assets available for benefits per the financial statements EBP, Change in Net Asset Available for Benefit, Increase After Plan Transfer EBP, Change in Net Asset Available for Benefit, Increase After Plan Transfer Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Summary of Significant Accounting Policies EBP, Summary of Accounting Policy [Text Block] Entity Registrant Name Entity Registrant Name Notes Receivable from Participants Notes Receivable From Participants [Member] Notes Receivable From Participants Schedule of Master Trust Net Assets EBP, Master Trust [Table Text Block] Schedule H, Line 4a - Schedule of Delinquent Participant Contributions EBP, Schedule of Delinquent Participant Contribution [Text Block] EBP, Schedule of Delinquent Participant Contribution [Table] EBP, Schedule of Delinquent Participant Contribution [Table] Subsequent Events EBP, Subsequent Event [Policy Text Block] Maximum borrowing, to total account, percentage EBP, Note Receivable from Participant, Account, Maximum Borrowing, to Total Account, Percentage Document Information [Table] Document Information [Table] Notes Receivable from Participants EBP, Note Receivable from Participant [Policy Text Block] Total investment income EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment EBP, Nonconsolidated, Master Trust and Plan Interest in Master Trust [Axis] EBP, Nonconsolidated, Master Trust and Plan Interest in Master Trust [Axis] Contributions Not Corrected EBP, Schedule of Delinquent Participant Contribution, Not Corrected Other EBP, Other Receivable NET ASSETS AVAILABLE FOR BENEFITS Net assets available for benefits at beginning of year Net assets available for benefits at end of year Net assets available for benefits as reported in financial statements EBP, Net Asset Available for Benefit Entity [Domain] Entity [Domain] Contributions: EBP, Change in Net Asset Available for Benefit, Increase from Contribution [Abstract] Amount payable to recordkeeper EBP, Related Party And Party-In-Interest Transactions, Amount Payable To Recordkeeper EBP, Related Party And Party-In-Interest Transactions, Amount Payable To Recordkeeper Pretax, maximum employee deferral or rollover, percentage EBP, Participant Contribution, Pretax, Maximum Annual Employee Deferral Or Rollover, Percentage EBP, Participant Contribution, Pretax, Maximum Annual Employee Deferral Or Rollover, Percentage Forfeited nonvested account EBP, Forfeited Nonvested Account Matching percentage EBP, Employer Contribution, Matching Percentage Net assets reported on Schedule H on Form 5500 EBP, Form 5500 Caption, Net Assets NAV Fair Value Measured at Net Asset Value Per Share [Member] EBP, Investment, Fair Value and NAV [Table] EBP, Investment, Fair Value and NAV [Table] Interest in master trust EBP, Interest in Master Trust, Percentage EBP, Statement of Net Asset Available for Benefit [Line Items] EBP, Statement of Net Asset Available for Benefit [Line Items]