Statistical Measurement [Domain] Statistical Measurement [Domain] Transactions with Parties-in-Interest EBP, Related Party and Party-in-Interest Transactions [Text Block] Interest income on notes receivable from participants EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Note Receivable from Participant Document Information [Line Items] Document Information [Line Items] Capital One Stock Fund EBP, Employer, Common Stock Fund [Member] Note receivable from participant, maximum borrowing, amount EBP, Note Receivable from Participant, Account, Maximum Borrowing, Amount Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] EBP, Description of Plan and Accounting Change [Abstract] Investment Type [Axis] Investment Type [Axis] Rollovers EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Rollover Note receivable from participant, maximum borrowing, to total account EBP, Note Receivable from Participant, Account, Maximum Borrowing, to Total Account, Percentage Other receivables EBP, Other Receivable Participant loan, variable rate EBP, Participant Loan, Basis Spread On Variable Rate EBP, Participant Loan, Basis Spread On Variable Rate Number of shares (in shares) EBP, Investment, Number of Shares Income Tax Status EBP, Tax Status [Text Block] Total liabilities EBP, Liability Change in benefits payable to participants EBP, Reconciliation to Form 5500, Payment to Participant, Increase from Allocation to Withdrawing Participant, Not yet Paid EBP, Description of Plan [Line Items] EBP, Description of Plan [Line Items] Interest and dividends on investments EBP, Change in Net Asset Available for Benefit, Increase from Interest and Dividend Income on Investment Fair Value of Plan Investment Options Managed by Parties in Interest EBP, Related Party and Party-in-Interest Transactions [Table Text Block] EBP, Schedule of Asset Held for Investment [Table] EBP, Schedule of Asset Held for Investment [Table] Notes receivable from participants EBP, Asset Held for Investment, Participant Loan, after Deemed Distribution EBP, Employer Contribution, Tranche Two EBP, Employer Contribution, Tranche Two [Member] EBP, Employer Contribution, Tranche Two Net assets available for benefits, per Form 5500 EBP, Form 5500 Caption, Net Assets Fair Value Measurement EBP, Investment, Fair Value and NAV [Text Block] Investment cost EBP, Investment Acquired, Excluding Plan Interest in Master Trust, Cost EBP, Investment, Fair Value and NAV [Table] EBP, Investment, Fair Value and NAV [Table] Total contributions EBP, Change in Net Asset Available for Benefit, Increase from Contribution Net income (loss), per Form 5500 EBP, Form 5500 Caption, Net Income (Loss) Note receivable from participant, minimum borrowing, amount EBP, Note Receivable from Participant, Account, Minimum Borrowing, Amount EBP, Related Party and Party-in-Interest Transactions [Table] EBP, Related Party and Party-in-Interest Transactions [Table] EBP, Investments [Table] EBP, Fully Benefit-Responsive Investment Contract [Table] Benefits paid to participants EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant Participants EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Excluding Rollover Cash and equivalents EBP, Investment, Par or Maturity Value Net assets available for benefits Beginning of year End of year Net assets available for benefits EBP, Net Asset Available for Benefit EBP, Reconciliation of Financial Statement to Form 5500 [Line Items] EBP, Reconciliation of Financial Statement to Form 5500 [Line Items] EBP, Schedule of Asset Held for Investment [Line Items] EBP, Schedule of Asset Held for Investment [Line Items] EBP, Accounting Policy [Line Items] EBP, Accounting Policy [Line Items] Total investments EBP, Investment, Excluding Plan Interest in Master Trust, Fair and Contract Value EBP, Investments [Line Items] EBP, Fully Benefit-Responsive Investment Contract [Line Items] Total assets EBP, Asset EBP, Employer Contribution, Tranche One EBP, Employer Contribution, Tranche One [Member] EBP, Employer Contribution, Tranche One EBP, Employer Contribution, Type [Axis] EBP, Employer Contribution, Type [Axis] EBP, Employer Contribution, Type EBP, Reconciliation of Financial Statement to Form 5500 EBP, Reconciliation of Financial Statement to Form 5500 [Table Text Block] Maximum eligible compensation EBP, Participant Contribution, Maximum Contribution to Eligible Compensation, Percentage EBP, Participant Contribution, Maximum Contribution to Eligible Compensation, Percentage EBP, Reconciliation of Financial Statement to Form 5500 [Table] EBP, Reconciliation of Financial Statement to Form 5500 [Table] EBP, Employer, Common Stock EBP, Employer, Common Stock [Member] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] EBP, Tax Status [Abstract] Net increase in net assets available for benefits Net increase (decrease) in net assets available for benefits, per the financial statements EBP, Change in Net Asset Available for Benefit, Increase (Decrease) Cover [Abstract] Employer EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Cash Maximum Maximum [Member] Assets: EBP, Asset [Abstract] Minimum Minimum [Member] Increase from dividend income on investment EBP, Change in Net Asset Available for Benefit, Increase from Dividend Income on Investment EBP, Schedule of Asset Held for Investment [Abstract] Reconciliation of Financial Statements to Form 5500 EBP, Reconciliation of Financial Statement to Form 5500 [Text Block] EBP 002 EBP 002 [Member] EBP 002 Entity [Domain] Entity [Domain] Total as of December 31, 2025 EBP, Asset Held for Investment Investment, Identifier [Axis] Investment, Identifier [Axis] Transfer from Discover Financial Services 401k Plan EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan EBP, Investment, Fair Value and NAV [Abstract] Employer matching contribution EBP, Employer Matching Contribution [Member] EBP, Employer Matching Contribution Employer contribution matching, percentage EBP, Employer Contribution, Matching Percentage Basis of Presentation EBP, Basis of Accounting [Policy Text Block] EBP, Subsequent Event [Line Items] EBP, Subsequent Event [Line Items] Associate deferrals EBP, Participant Contribution, Maximum Contribution to Associate Deferrals, Percentage EBP, Participant Contribution, Maximum Contribution to Associate Deferrals, Percentage Risk and Uncertainties EBP, Risk and Uncertainty [Policy Text Block] EBP, Tax Status [Line Items] EBP, Tax Status [Line Items] EBP, Statement of Change in Net Asset Available for Benefit [Table] EBP, Statement of Change in Net Asset Available for Benefit [Table] Benefits payable to participants EBP, Reconciliation to Form 5500, Net Asset Available for Benefit, Allocation to Withdrawing Participant, Not yet Paid EBP, Description of Plan [Table] EBP, Description of Plan [Table] EBP, Reconciliation of Financial Statement to Form 5500 [Abstract] Investment Valuation and Income Recognition EBP, Investment [Policy Text Block] Investments, at contract value EBP, Investment, Excluding Plan Interest in Master Trust, Contract Value Other liabilities EBP, Other Liability Amendment Flag Amendment Flag Administrative expenses EBP, Change in Net Asset Available for Benefit, Decrease from Administrative Expense Collective investment trusts Common Collective Trust [Member] Reversal of prior year adjustment from contract value to fair value for fully benefit-responsive investment contracts EBP, Reconciliation to Form 5500, Change in Net Asset Available for Benefit, Prior Period, Increase from Deemed Distribution EBP, Investment, Fair Value and NAV EBP, Investment, Fair Value and NAV [Table Text Block] Total deductions EBP, Change in Net Asset Available for Benefit, Decrease Current Value EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value EBP, Statement of Change in Net Asset Available for Benefit [Abstract] EBP, Subsequent Event [Table] EBP, Subsequent Event [Table] Investment selling price EBP, Investment Sold, Excluding Plan Interest in Master Trust, Selling Price EBP, Related Party and Party-in-Interest Transactions [Abstract] Forfeited non-vested accounts EBP, Forfeited Nonvested Account EBP, Related Party and Party-in-Interest Transactions [Line Items] EBP, Related Party and Party-in-Interest Transactions [Line Items] Forfeited non-vested accounts, decrease from employer contribution EBP, Forfeited Nonvested Account, Decrease from Employer Contribution EBP, Statement of Net Asset Available for Benefit [Abstract] Loans deemed distributed EBP, Reconciliation to Form 5500, Net Asset Available for Benefit, Deemed Distribution Description of Plan EBP, Description of Plan [Text Block] Summary of Significant Accounting Policies EBP, Summary of Accounting Policy [Text Block] Employer Contribution [Axis] Employer Contribution [Axis] Employer Contribution Notes Receivable from Participants EBP, Note Receivable from Participant [Policy Text Block] Total additions EBP, Change in Net Asset Available for Benefit, Increase EBP, Statement of Net Asset Available for Benefit [Line Items] EBP, Statement of Net Asset Available for Benefit [Line Items] Entity Central Index Key Entity Central Index Key Investments, at fair value EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value Legal Entity [Axis] Legal Entity [Axis] Entity tax identification number Entity Tax Identification Number Fidelity Brokerage Link EBP, Fidelity Brokerage Link [Member] EBP, Fidelity Brokerage Link Net investment income EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment EBP, Accounting Policy, Accounting Standard Update, and Change in Accounting Principle [Abstract] Interest rates EBP, Investment, Interest Rate Plan number EBP, Plan Number Safe-harbor non-elective contribution EBP, Employer Contribution, Safe-Harbor Non-Elective Contribution [Member] EBP, Employer Contribution, Safe-Harbor Non-Elective Contribution Contributions: EBP, Change in Net Asset Available for Benefit, Increase from Contribution [Abstract] Document Type Document Type EBP, Statement of Net Asset Available for Benefit [Table] EBP, Statement of Net Asset Available for Benefit [Table] EBP, Investment, Fair Value and NAV [Line Items] EBP, Investment, Fair Value and NAV [Line Items] Use of Estimate EBP, Use of Estimate [Policy Text Block] EBP, Fully Benefit-Responsive Investment Contract [Abstract] Deductions: EBP, Change in Net Asset Available for Benefit, Decrease [Abstract] Statistical Measurement [Axis] Statistical Measurement [Axis] Unsettled trades in conjunction with Plan Merger EBP, Investment Sale, Receivable Notes receivable from participants, maturing through 2035, 3.25% - 10.5% interest rates EBP, Note Receivable from Participant Investments EBP, Investment [Text Block] EBP, Investment Level 2 Fair Value, Inputs, Level 2 [Member] Schedule H, Line 4i – Schedule of Assets (Held At End of Year) EBP, Schedule of Asset Held for Investment [Table Text Block] Additions: EBP, Change in Net Asset Available for Benefit, Increase [Abstract] Change in deemed loans distributions EBP, Reconciliation to Form 5500, Change in Net Asset Available for Benefit, Increase (Decrease) from Deemed Distribution Adjustment from contract value to fair value for fully benefit-responsive investment contracts EBP, Reconciliation to Form 5500, Change in Net Asset Available for Benefit, Increase (Decrease) from Contract Value to Current Value Net appreciation of investments EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Gain (Loss) on Investment EBP, Accounting Policy [Table] EBP, Accounting Policy [Table] Investments [Domain] Investments [Domain] EBP, Subsequent Event [Abstract] Self-managed funds EBP, Self-Directed Brokerage Account [Member] Document Information [Table] Document Information [Table] Registered investment companies EBP, Registered Investment Companies [Member] EBP, Registered Investment Companies EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Statement of Change in Net Asset Available for Benefit [Line Items] Net assets available for benefits: EBP, Net Asset Available for Benefit [Abstract] Employer Contribution [Domain] Employer Contribution [Domain] Employer Contribution [Domain] Adjustment from contract value to fair value for fully benefit-responsive investment contracts EBP, Reconciliation to Form 5500, Net Asset Available for Benefit, Contract Value to Current Value Adjustment Level 1 Fair Value, Inputs, Level 1 [Member] Entity Registrant Name Entity Registrant Name Subsequent Events EBP, Subsequent Event [Text Block] Company's Contribution Structure EBP, Contribution [Table Text Block] Investment income: EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment [Abstract] EBP, Tax Status [Table] EBP, Tax Status [Table] Total Value of Holdings EBP, Investment, Excluding Plan Interest in Master Trust, Cost Liabilities: EBP, Liability [Abstract] EBP, Employer Contribution, Type [Domain] EBP, Employer Contribution, Type [Domain] EBP, Employer Contribution, Type [Domain] Receivables: EBP, Receivable [Abstract] Total annual contribution opportunity EBP, Employer Contribution, Participant Compensation Matched, Percentage