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Liabilities and Equity Liabilities and Equity [Abstract] Tier 1 Capital (to Average Assets) Banking Regulation, Tier 1 Leverage Capital, Well Capitalized, Minimum Cover page. 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Partner Relationships Income before income tax expense Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Entity Shell Company Entity Shell Company Tier 1 Capital (to Average Assets) Banking Regulation, Tier 1 Leverage Capital Ratio, Actual Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Gross Proceeds Proceeds from Issuance of Debt Other impacts to the provisions for credit losses: Financing Receivable, Credit Loss, Expense (Reversal), Other Impacts Financing Receivable, Credit Loss, Expense (Reversal), Other Impacts Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Total interest-bearing liabilities, difference Financial Liabilities Fair Value Disclosure, Difference Between Carrying Value and Fair Value Financial Liabilities Fair Value Disclosure, Difference Between Carrying Value and Fair Value Schedule of Cash Flow, Supplemental Disclosures Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Unrealized gains (losses) on cash flow hedges Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax Change in unrealized gains (losses) for the period included in other comprehensive income for assets held at the end of the reporting period Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), OCI Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Short-term borrowings: Short-Term Debt [Abstract] Line of Credit Facility [Table] Line of Credit Facility [Table] Total interest expense Interest expense Interest Expense, Operating Interest income: Investment Income, Interest and Dividend [Abstract] Schedule of Interest Bearing Deposits Interest Bearing Deposits [Table Text Block] [Table Text Block] for Interest Bearing Deposits [Table] Financing receivable, modified in period, to total financing receivables, percentage Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage Texas TEXAS Current period gross charge-offs, Year 4 Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest, Writeoff, Originated Three Years Before Latest Fiscal Year Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest, Writeoff, Originated Three Years Before Latest Fiscal Year Gains on Sale of Loans, Net Transfers and Servicing of Financial Assets, Transfers of Financial Assets, Sales, Policy [Policy Text Block] Fixed-rate borrowings Fixed Rate Borrowings [Member] Fixed Rate Borrowings [Member] Accrued interest to be capitalized Accrued Interest to be Capitalized [Abstract] Accrued Interest to be Capitalized Software Software and Software Development Costs [Member] Total accrued interest by origination vintage, Year 1 Financing Receivable, Accrued Interest, Origination Vintage, Originated in Current Fiscal Year Financing Receivable, Accrued Interest, Origination Vintage, Originated in Current Fiscal Year Document Fiscal Period Focus Document Fiscal Period Focus Goodwill and acquired intangible assets, net Intangible Assets, Net (Including Goodwill) Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Seasoning based on monthly scheduled payments due from 37 - 48 payments Seasoning Based On Monthly Scheduled Payments Due From Thirty Seven To Forty Eight Payments In Percent Seasoning based on monthly scheduled payments due from thirty seven to forty eight payments in percent. 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Total deferred tax assets Deferred Tax Assets, Net of Valuation Allowance Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Current period gross charge-offs, Year 3 Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest, Writeoff, Originated Two Years Before Latest Fiscal Year Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest, Writeoff, Originated Two Years Before Latest Fiscal Year Statement of Income Location, Balance [Domain] Statement of Income Location, Balance [Domain] Restricted Stock Units (RSUs) Restricted Stock Units (RSUs) [Member] Allowance for Credit Losses Credit Loss, Financial Instrument [Policy Text Block] Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Interest expense on short-term borrowings Interest Expense, Short-Term Borrowings Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items] Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items] 2046 Maturity 2046 [Member] Maturity 2046 [Member] Decreases related to settlements with taxing authorities Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities Entity Emerging Growth Company Entity Emerging Growth Company Stated maturity, 2028 Long-Term Debt, Maturity, Year Three Changes in operating assets and liabilities: Increase (Decrease) in Operating Assets [Abstract] Seasoning based on monthly scheduled payments due from not yet in repayment Seasoning Based On Monthly Scheduled Payments Due From Not Yet In Repayment In Percent Seasoning based on monthly scheduled payments due from not yet in repayment in percent Cash collateral pledged Derivative Liability, Subject to Master Netting Arrangement, Collateral, Right to Reclaim Cash Not Offset Beginning balance (in shares) Ending balance (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number Parent Only Statements Condensed Financial Information of Parent Company Only Disclosure [Text Block] Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Total Derivative, Gain (Loss) on Derivative, Net Financing Receivable, excluding accrued interest, modified, accumulated Financing Receivable, Excluding Accrued Interest, Modified, Accumulated Investment, Proportional Amortization Method, Elected, Statement of Financial Position [Extensible Enumeration] Investment, Proportional Amortization Method, Elected, Statement of Financial Position [Extensible Enumeration] Total non-interest income Noninterest Income Beginning balance (in shares) Ending balance (in shares) Common stock shares outstanding (in shares) Common Stock, Shares, Outstanding Gains on sales of loans, net Gains on sale of loans, net Gain (Loss) on Sales of Loans, Net Weighted Average Interest Rate Long-Term and Short Term Debt, Weighted Average Interest Rate, at Point in Time Long-Term and Short Term Debt, Weighted Average Interest Rate, at Point in Time Loans Held for Investment Loans Held for Sale Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Operating expenses: Noninterest Expense [Abstract] Seasoning Repayments [Member] Repayments credit quality indicators that are developed and used internally by the company. Unfunded loan held-for-sale Unfunded Loan Held-for-Sale Unfunded Loan Held-for-Sale Cash due from depository institutions Cash and Due from Banks Low income housing tax credit investments Investment Program, Proportional Amortization Method, Elected, Income Tax Credit and Other Income Tax Benefit, before Amortization Expense Class of Financing Receivable [Domain] Class of Financing Receivable [Domain] Current provision (benefit): Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Schedule Of Allowance For Credit Losses And Recorded Investment In Financing Receivables Table [Table] Schedule Of Allowance For Credit Losses And Recorded Investment In Financing Receivables Table [Table] Schedule Of Allowance For Credit Losses And Recorded Investment In Financing Receivables Table [Table] Valuation allowance Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount Gain (loss) on sale of financing receivable Gain (Loss) on Sale of Financing Receivable Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Utah Housing Corporation bonds Utah Housing Corporation Bonds [Member] Utah Housing Corporation Bonds [Member] Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract] Number of Shares Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restatement Determination Date Restatement Determination Date Income tax expense Provision for income tax expense Income tax expense (benefit) Income Tax Expense (Benefit) 90 Days or Greater Past Due Greater Than Ninety Days Past Due Accrued Interest Receivable Greater than ninety days past due accrued interest receivable. Other assets Other Assets, Net Other Assets Balance, beginning of period Balance, end of period Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Senior Unsecured Notes Due October 29, 2025 Senior Unsecured Notes Due January 31, 2030 [Member] Senior Unsecured Notes Due January 31, 2030 Document Information [Line Items] Document Information [Line Items] Preferred stock, shares issued (in shares) Preferred Stock, Shares Issued After five years Time Deposit Maturities, after Year Five Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Designated as Hedging Instrument Designated as Hedging Instrument [Member] Tier 1 of government guarantee (at least) Tier One of Government Guarantee Tier One of Government Guarantee Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Provisions for unfunded loan commitments Financing Receivable, Credit Loss, Expense (Reversal), Existing Commitments Financing Receivable, Credit Loss, Expense (Reversal), Existing Commitments Schedule of Deposits Schedule of Deposits [Table Text Block] Schedule of Deposits [Table Text Block] Hedging Relationship [Axis] Hedging Relationship [Axis] Decrease in investment in subsidiaries, net Decrease (Increase) in Investments in Subsidiaries, Net Decrease (Increase) in Investments in Subsidiaries, Net Premises and equipment, gross Property, Plant and Equipment, Gross Regulatory Assets and Liabilities Disclosure [Abstract] Total Private Education Loans, Year 5 Loans, Originated Four Years Before Latest Fiscal Year Loans, Originated Four Years Before Latest Fiscal Year Rule 10b5-1 Trading Plan Rule 10b5-1 Trading Plan [Member] Rule 10b5-1 Trading Plan Employer contribution amount Defined Contribution Plan, Employer Discretionary Contribution Amount Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Deposits, difference Deposits, Fair Value Disclosure, Difference Between Carrying Value And Fair Value Deposits, Fair Value Disclosure, Difference Between Carrying Value And Fair Value Current period recoveries, Year 2 Financing Receivable, Allowance for Credit Loss, Recovery, Originated In Fiscal Year Before Latest Fiscal Year Financing Receivable, Allowance for Credit Loss, Recovery, Originated In Fiscal Year Before Latest Fiscal Year Cash received from option exercises Proceeds from Stock Options Exercised Percentage of aggregate outstanding loans held for investment Percentage of Aggregate Outstanding Loans Held For Investment Percentage of Aggregate Outstanding Loans Held For Investment Funds on deposit with the FRB Certificates of Deposit, at Carrying Value U.S. federal Income Tax Paid, Federal, after Refund Received Buildings and leasehold improvements Building and Building Improvements [Member] All Trading Arrangements All Trading Arrangements [Member] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Acquired intangible assets Deferred Tax Assets, Goodwill and Intangible Assets Preferred stock dividends Preferred stock dividends Preferred Stock Dividends, Income Statement Impact Other, net Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Deferred tax liabilities: Deferred Tax Liabilities, Gross [Abstract] Other income Noninterest Income, Other Operating Income Beginning balance (in shares) Ending balance (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number Three Month LIBOR Three Month LIBOR [Member] Three Month LIBOR [Member] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Total net cash used in operating activities Total net cash used in operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Write-downs arising from transfer of loans to held for sale Financing Receivable, Excluding Accrued Interest, Reclassification to Held-for-Sale Private Education Loans allowance for losses, Year 1 Financing Receivable, Allowance For Credit Loss, Originated In Current Fiscal Year Financing Receivable, Allowance For Credit Loss, Originated In Current Fiscal Year Increase in non-marketable securities Increase (Decrease) in Equity Securities, FV-NI Loans Transferred to the Trust by Third-Party Seller Proceeds from Sale of Debt Securities, Available-for-Sale Preferred stock, par or stated value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Subsequent Event Subsequent Event [Member] Net interest income Net interest loss Interest Income (Expense), Operating Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] PEO Total Compensation Amount PEO Total Compensation Amount Tier 1 Capital (to Risk-Weighted Assets) Banking Regulation, Tier 1 Risk-Based Capital, Actual Depreciation of premises and equipment Depreciation of premises and equipment Depreciation Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Private education loans Percent Of Private Loans Percent of private loans Gross position Derivative Liability, Subject to Master Netting Arrangement, before Offset Restricted Stock Units And Performance Stock Units Restricted Stock Units And Performance Stock Units [Member] Restricted Stock Units and Performance Stock Units [Member] Equity Components [Axis] Equity Components [Axis] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Year 4 Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year Fair value of restricted stock units that vested and converted to common stock Fair Value Of Restricted Stock Units That Vested And Converted To Common Stock Total fair value of restricted stock units that vested and converted to common stock. Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Interest income from term deposit facility Interest income from Term Deposit Facility Interest income from Term Deposit Facility Number of reportable segments Number of Reportable Segments Defined Contribution Plans Compensation and Employee Benefit Plans [Text Block] Private Education Loans, net, Year 3 Financing Receivable, after Allowance for Credit Loss, Originated Two Years Before Current Fiscal Year Financing Receivable, after Allowance for Credit Loss, Originated Two Years Before Current Fiscal Year 2022 Share Repurchase Program 2022 Share Repurchase Program [Member] 2022 Share Repurchase Program Industry of Counterparty, Type [Axis] Industry of Counterparty, Type [Axis] Entity Address, State or Province Entity Address, State or Province Total interest income Interest income Interest and Dividend Income, Operating Financial Asset, Period Past Due [Domain] Financial Asset, Aging [Domain] Private Education Loans Loans Receivable, Fair Value Disclosure Period of deferment Period Of Deferment For Adoption Of New Accounting Pronouncements Period Of Deferment For Adoption Of New Accounting Pronouncements Total earning assets, difference Assets, Fair Value Disclosure, Difference Between Carrying Value And Fair Value Assets, Fair Value Disclosure, Difference Between Carrying Value And Fair Value Individual: Individual [Axis] Other liabilities reserve Other Liabilities Reserve Other Liabilities Reserve Income Tax Jurisdiction [Domain] Income Tax Jurisdiction [Domain] Common stock dividends paid Payments of Ordinary Dividends, Common Stock Document Annual Report Document Annual Report Private education loan term accounted for as a secured financing Loan, Held-for-Sale or Securitization or Asset-Backed Financing Arrangement, Principal Outstanding Current period gross charge-offs, Year 2 Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest, Writeoff, Originated In Fiscal Year Before Latest Fiscal Year Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest, Writeoff, Originated In Fiscal Year Before Latest Fiscal Year Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Total accrued interest by origination vintage Financing Receivable, Accrued Interest, Origination Vintage, before Allowance for Credit Loss Financing Receivable, Accrued Interest, Origination Vintage, before Allowance for Credit Loss Research and development costs Deferred Tax Asset, In-Process Research and Development Entity Interactive Data Current Entity Interactive Data Current 2058 Maturity 2058 [Member] Maturity 2058 Investments Interest Income, Debt Securities, Available-for-Sale, Operating Condensed Income Statement [Table] Condensed Income Statement [Table] Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Asset, Gain (Loss), Statement of Other Comprehensive Income or Comprehensive Income [Extensible Enumeration] Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Asset, Gain (Loss), Statement of Other Comprehensive Income or Comprehensive Income [Extensible Enumeration] Aggregate Intrinsic Value, Exercisable, ending balance Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Intrinsic Value Total non-interest expenses Non-interest expenses Noninterest Expense Schedule of Accrued Interest Receivable Accrued Interest Receivable [Table Text Block] Accrued interest receivable. Variable rate Percentage Reimbursement On All Qualifying Default Claims Period Three Percentage reimbursement on all qualifying default claims period three. Allowance for Credit Losses and Unfunded Loan Commitments Allowance for Credit Losses [Text Block] Deposits Interest Expense, Deposits Property, Plant and Equipment, Type [Axis] Long-Lived Tangible Asset [Axis] Non-interest income: Noninterest Income [Abstract] Derivative, fair value, amount offset against collateral, net Derivative, Fair Value, Amount Offset Against Collateral, Net Money market Interest-Bearing Domestic Deposit, Money Market Uncommitted federal funds Uncommitted Federal Funds Uncommitted Federal Funds Less: provisions for credit losses Provisions for credit losses Provisions for credit losses Financing Receivable And Off-Balance Sheet, Excluding Accrued Interest, Credit Loss, Expense (Reversal) Financing Receivable And Off-Balance Sheet, Excluding Accrued Interest, Credit Loss, Expense (Reversal) Total SLM Corporation stockholders’ equity before treasury stock Stockholders' Equity Attributable to Parent, Excluding Treasury Stock Stockholders' Equity Attributable to Parent, Excluding Treasury Stock Measurement input Debt Securities, Trading, Measurement Input Condensed Financial Statements [Table] Condensed Financial Statements [Table] Accrued interest on deposits Interest Payable, Current Private Education Loans, net, Year 2 Financing Receivable, after Allowance for Credit Loss, Originated In Fiscal Year Before Latest Fiscal Year Financing Receivable, after Allowance for Credit Loss, Originated In Fiscal Year Before Latest Fiscal Year Trading investments, cost Debt Securities, Trading, Amortized Cost Entity Central Index Key Entity Central Index Key PEO Name PEO Name Schedule of Maturities of Long-term Debt Schedule of Maturities of Long-Term Debt [Table Text Block] Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] 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Information, by Segment [Table] Schedule of Impact of Derivatives on the Consolidated Balance Sheet Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] 2024-R1 ABS transaction SMB Private Education Loan Trust 2024-R1 [Member] SMB Private Education Loan Trust 2024-R1 Exercise Price Award Exercise Price Entity Filer Category Entity Filer Category Class of Stock [Domain] Class of Stock [Domain] Statutory rate Statutory U.S. federal rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Greater than or equal to 750 FICO score greater than 750 [Member] FICO score greater than 750 [Member] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Private Education Loans allowance for losses, Year 6 Financing Receivable, Allowance For Credit Loss, Originated Five Years Before Current Fiscal Year Financing Receivable, Allowance For Credit Loss, Originated Five Years Before Current Fiscal Year Industry of Counterparty [Domain] Industry of Counterparty [Domain] Total Private Education Loans, gross, Year 2 Loans Gross, Originated In Fiscal Year Before Latest Fiscal Year Loans Gross, Originated In Fiscal Year Before Latest Fiscal Year Deposits Deposits [Policy Text Block] Deposits [Policy Text Block] Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Assets/(Liabilities) Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease) Accrued interest payable Accrued Liabilities, Fair Value Disclosure Expected amortization of 2028 Finite-Lived Intangible Asset, Expected Amortization, Year Three Percentage reimbursement on all qualifying default claims period two (as a percentage) Percentage Reimbursement On All Qualifying Ffelp Default Claims Period Two Percentage Reimbursement On All Qualifying FFELP Default Claims Period Two Deferred tax assets: Deferred Tax Assets, Net [Abstract] Cost Basis Finite-Lived Intangible Assets, Gross Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Current period net charge-offs, Year 4 Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery, Originated Three Years Before Current Fiscal Year Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery, Originated Three Years Before Current Fiscal Year % of Balance Percent Of Balance [Abstract] Percent Of Balance Entity Address, Address Line One Entity Address, Address Line One Employee Stock Purchase Plan Employee Stock Purchase Plan [Member] Employee Stock Purchase Plan [Member] Total Private Education Loans in forbearance, Year 1 Financing Receivable, Loans In Forbearance, Originated In Current Fiscal Year Financing Receivable, Loans In Forbearance, Originated In Current Fiscal Year Total Private Education Loans in forbearance, Year 2 Loans In Repayment, Originated In Fiscal Year Before Latest Fiscal Year Loans In Repayment, Originated In Fiscal Year Before Latest Fiscal Year Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Certificates of deposit Weighted Average Rate Domestic Deposit, Time Deposits Investments [Domain] Investments [Domain] Shares repurchased related to employee stock-based compensation plans (in shares) Shares repurchased related to employee stock-based compensation plans (in shares) Share-Based Payment Arrangement, Shares Withheld for Tax Withholding Obligation With cosigner With Cosigner [Member] With Cosigner [Member] Combination - Interest Rate Reduction and Term Extension Interest Rate Reduction And Term Extension [Member] Interest Rate Reduction And Term Extension Derivative Financial Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Delinquent Private Education Loans in repayment as a percentage of Private Education Loans in repayment, Year 6 Delinquencies As Percentage Of Loans In 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Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period Total Private Education Loans in forbearance, Year 6 Loans In Repayment, Originated Five Or More Years Before Current Fiscal Year Loans In Repayment, Originated Five Or More Years Before Current Fiscal Year Canceled (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period Unrecognized compensation cost Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Nitro Nitro College [Member] Nitro College Estimated Fair Value Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months Tier 1 Capital (to Risk-Weighted Assets) Banking Regulation, Tier 1 Risk-Based Capital Ratio, Actual Deposits Deposit Liabilities Disclosures [Text Block] Change in Unrecognized Tax Benefit, Reasonably Possible [Table] Change in Unrecognized Tax Benefit, Reasonably Possible [Table] Long-term borrowings Long-Term Debt, Fair Value Fair Value Measurement Inputs and Valuation Techniques Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Loans pledged to borrower in custody Loans pledged to Borrower in Custody Loans pledged to Borrower in Custody Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] U.S. government-sponsored enterprises and Treasuries US Government-sponsored Enterprises Debt Securities [Member] Condensed Financial Information Disclosure [Abstract] Condensed Financial Information Disclosure [Abstract] Decrease in trading investments Payments To Acquire Trading Securities Held-For-Sale Payments To Acquire Trading Securities Held-For-Sale Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Weighted 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Dividend Rate Estimated weighted average life of student loans Estimated Weighted Average Life Of Student Loans Estimated weighted average life of student loans. Certificates of deposit Certificates of Deposit [Member] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Fair Value Estimate of Fair Value Measurement [Member] Provisions for loan losses Financing Receivable, Credit Loss, Expense (Reversal), New Commitments Financing Receivable, Credit Loss, Expense (Reversal), New Commitments Net unrealized losses in valuation allowance Capital Loss, Valuation Allowance Capital Loss, Valuation Allowance Total principal amount, maturity to call date Debt Instrument, Face Amount, Maturity To Call Date Debt Instrument, Face Amount, Maturity To Call Date Total accrued interest by origination vintage, Year 4 Financing Receivable, Accrued interest, Origination Vintage, Originated Three Years before Latest Fiscal Year Financing Receivable, Accrued interest, Origination Vintage, Originated Three Years before Latest Fiscal Year Private Education Loans, net, Year 4 Financing Receivable, after Allowance for Credit Loss, Originated Three Years Before Current Fiscal Year Financing Receivable, after Allowance for Credit Loss, Originated Three Years Before Current Fiscal Year MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] (Increase) decrease in due from subsidiaries, net Increase (Decrease) in Due from Subsidiaries, Net Increase (Decrease) in Due from Subsidiaries, Net Loans Carrying Amount Of Assets Securing Debt Outstanding Loans Carrying Amount Of Assets Securing Debt Outstanding Loans After three years to four years Time Deposit Maturities, Year Four Documents Incorporated by Reference Documents Incorporated by Reference [Text Block] Current period net charge-offs, Year 5 Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery, Originated Four Years Before Current Fiscal Year Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery, Originated Four Years Before Current Fiscal Year Restricted cash Restricted Cash Restricted Cash and Investments Private Education Loans in forbearance, total Financing Receivable, Loans In Forbearance, before Allowance for Credit Loss Financing Receivable, Loans In Forbearance, before Allowance for Credit Loss Total carrying value of LIHTC investments Investment, Proportional Amortization Method, Elected, Amount Accumulated other comprehensive loss (net of tax benefit of $(13,446) and $(21,209), respectively) Accumulated other comprehensive loss (net of tax benefit of $(13,446) and $(21,209), respectively) Accumulated Other Comprehensive Income (Loss), Net of Tax Condensed Financial Statements, Captions [Line Items] Condensed Financial Statements, Captions [Line Items] Stated maturity, 2026 Long-Term Debt, Maturity, Year One Financial Instruments [Domain] Financial Instruments [Domain] Total deferred tax liabilities Deferred Tax Liabilities, Gross Stated maturity, 2030 Long-Term Debt, Maturity, Year Five Interest rate offered to borrowers facing financial difficulty Financing Receivable, Temporary Interest Rate Reduction, Financial Difficulty Status Financing Receivable, Temporary Interest Rate Reduction, Financial Difficulty Status Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] 2021 Share Repurchase Program 2021 Share Repurchase Program [Member] 2021 Share Repurchase Program Developed technologies Developed Technology Rights [Member] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Other Deferred Tax Assets Other Including Valuation Allowance Deferred tax assets other including valuation allowance. Banking Regulation, Regulatory Capital Requirement, Compliance [Table] Banking Regulation, Regulatory Capital Requirement, Compliance [Table] Minimum Minimum [Member] Net interest income after provisions for credit losses Interest Income (Expense), after Provision for Loan Loss Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Company Selected Measure Name Company Selected Measure Name Fair Value Measurement [Domain] Fair Value Measurement [Domain] 2055 Maturity 2055 [Member] Maturity 2055 Borrowings Debt Disclosure [Text Block] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount 2025-C ABS transaction SMB Private Education Loan Trust 2025-C [Member] SMB Private Education Loan Trust 2025-C Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Total unrealized gains (losses) Other Comprehensive Income (Loss), before Tax Cash Flow Hedges Effect of Cash Flow Hedges on Results of Operations [Abstract] Net income attributable to SLM Corporation common stock, diluted Net Income (Loss) Available to Common Stockholders, Diluted Collateral [Domain] Collateral Held [Domain] Senior Unsecured Notes Due November 2, 2026 Senior Unsecured Notes Due November 2, 2026 [Member] Senior Unsecured Notes Due November 2, 2026 Ninety or more days delinquent Financing Receivable, 90 Days or More Past Due, Still Accruing Commitments, Contingencies and Guarantees Commitments and Contingencies Disclosure [Text Block] Total net derivatives Derivative Assets (Liabilities), at Fair Value, Net Transfer - funded loans Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability, Commitments Funded Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability, Commitments Funded Net increase (decrease) in other deposits Net Increase In NOW Account Deposits Net Increase In NOW Account Deposits Average common and common equivalent shares outstanding (in shares) Weighted average shares used to compute diluted EPS (in shares) Weighted Average Number of Shares Outstanding, Diluted Weighted Average Interest Rate Short-Term Debt, Weighted Average Interest Rate, at Point in Time 1-12 payments Seasoning Based On Monthly Scheduled Payments Due From One To Twelve Payments [Member] Seasoning Based On Monthly Scheduled Payments Due From One To Twelve Payments [Member] Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Derivative [Table] Derivative [Table] Current period gross charge-offs, Year 5 Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest, Writeoff, Originated Four Years Before Latest Fiscal Year Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest, Writeoff, Originated Four Years Before Latest Fiscal Year Entity Small Business Entity Small Business Total Private Education Loans in forbearance, Year 3 Loans In Repayment, Originated Two Years Before Current Fiscal Year Loans In Repayment, Originated Two Years Before Current Fiscal Year Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Excess of net asset fair value over carrying value Excess Of Net Asset Fair Value Over Carrying Value Excess of net asset fair value over carrying value. Preferred stock, shares issued (in shares) Beginning balance, Preferred stock, shares issued (in shares) Ending balance, Preferred stock, shares issued (in shares) Preferred Stock, Shares Outstanding Scholly, Inc. Scholly, Inc. [Member] Scholly, Inc. U.S. State Current State and Local Tax Expense (Benefit) Document Transition Report Document Transition Report Series B: 2.5 million and 2.5 million shares issued, respectively, at stated value of $100 per share Preferred Stock, Value, Outstanding Underlying Securities Award Underlying Securities Amount Gain on Sale for Additional Loans Transferred by Bank Debt Securities, Available-for-Sale, Realized Gain Equity Component [Domain] Equity Component [Domain] Document Period End Date Document Period End Date Seasoning based on monthly scheduled payments due from more than 48 payments Seasoning Based On Monthly Scheduled Payments Due From More Than Forty Eight Payments In Percent Seasoning based on monthly scheduled payments due from more than forty eight payments in percent Cash due from Federal Reserve Bank Cash due from Federal Reserve Bank Cash due from Federal Reserve Bank Income Taxes Income Tax Disclosure [Text Block] Loan Deferment Loan Deferment [Member] Loan Deferment Contractual obligation Contractual Obligation Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Not yet in repayment Seasoning Based On Monthly Scheduled Payments Due From Not Yet In Repayment [Member] Seasoning Based On Monthly Scheduled Payments Due From Not Yet In Repayment [Member] Deposits exceeding FDIC insurance limits Cash, Uninsured Amount Net position Derivative Asset, Including Not Subject to Master Netting Arrangement, after Offset and Deduction Weighted Average Remaining Contractual Term, Exercisable, ending balance Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Total equity Equity, Including Portion Attributable to Noncontrolling Interest 2053 Maturity 2053 [Member] Maturity 2053 2050 Maturity 2050 [Member] Maturity 2050 Average purchase price per share (in dollars per share) Shares Acquired, Average Cost Per Share Risks and Uncertainties [Abstract] Risks and Uncertainties [Abstract] Amortization of discount on Unsecured Borrowings Amortization of Debt Discount (Premium) Document Type Document Type Level 3  Fair Value, Inputs, Level 3 [Member] Earnings Per Common Share Earnings Per Share [Text Block] Name Outstanding Recovery, Individual Name Additional paid-in capital Additional paid-in capital Additional Paid in Capital Statistical Measurement [Axis] Statistical Measurement [Axis] Identifiable intangible assets aggregate fair value at acquisition date Finite-Lived Intangible Assets Acquired Total principal amount, after adjustments Debt Instrument, Face Amount, After Adjustments Debt Instrument, Face Amount, After Adjustments Aggregate purchase price (not to exceed) Share Repurchase Program, Authorized, Amount Unused fee percentage Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Credit Score, FICO [Domain] Credit Score, FICO [Domain] Gains (losses) on securities, net Gain (Loss) on Investments [Member] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Total Private Education Loans, Year 4 Loans, Originated Three Years Before Latest Fiscal Year Loans, Originated Three Years Before Latest Fiscal Year Total intrinsic value of options exercised Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period, Intrinsic Value Interest-bearing Deposit Liabilities, Domestic, by Component [Abstract] Interest-Bearing Deposit Liabilities, Domestic, by Component [Abstract] Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Well Capitalized Regulatory Requirements, Ratio Banking Regulation, Leverage Ratio [Abstract] Net income attributable to SLM Corporation common stock Net income attributable to SLM Corporation common stock, basic Net Income (Loss) Available to Common Stockholders, Basic Share Repurchase Program [Domain] Share Repurchase Program [Domain] SMB Private Education Loan Trust 2024 SMB Private Education Loan Trust 2024 [Member] SMB Private Education Loan Trust 2024 Aggregate Intrinsic Value Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Additional Disclosures [Abstract] Variable-rate Variable-rate Variable Income Interest Rate [Member] Period of positive payment performance required by a borrower between successive grants of forbearance Financing Receivable, Period Of Positive Payment Performance Required Between Forbearance Grants Financing Receivable, Period Of Positive Payment Performance Required Between Forbearance Grants Combination - 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repaid Borrowings Repaid Borrowings Repaid Common stock repurchased Stock Repurchased and Retired During Period, Value Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statement [Table] Financing Receivable Portfolio Segment [Axis] Financing Receivable Portfolio Segment [Axis] Domestic Tax Jurisdiction Domestic Tax Jurisdiction [Member] Total Private Education Loans, gross, Year 4 Loans Gross, Originated Three Years Before Latest Fiscal Year Loans Gross, Originated Three Years Before Latest Fiscal Year Total Available-For-Sale Securities, Unrealized Loss Position [Abstract] Available-For-Sale Securities, Unrealized Loss Position [Abstract] Total income taxes paid (net of refunds received) Income Taxes Paid, Net One year or less Time Deposit Maturities, Year One Percentage of Private Education Loans in repayment, Year 5 Percentage Of Loans In Repayment, Originated Four Years Before Latest Fiscal Year Percentage Of Loans In Repayment, Originated Four Years Before Latest Fiscal Year Expected amortization of 2027 Finite-Lived Intangible Asset, Expected Amortization, Year Two Certificates of deposit Interest-Bearing Domestic Deposit, Time Deposits Granted (in dollars per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Premises and Equipment, net Property, Plant and Equipment Disclosure [Text Block] FICO at Origination School Fico [Member] School type fico credit quality indicators that are developed and used internally by the company. Schedule of Compliance with Regulatory Capital Requirements Under Banking Regulations Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block] Loan type Loan type Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss Stable interest-bearing deposits, total Stable Interest-bearing Deposits, Total Stable Interest-bearing Deposits, Total Net unrealized losses Deferred Tax Asset, Debt Securities, Trading, Unrealized Loss Schedule of Available-for-Sale Securities, Continuous Unrealized Loss Position, Fair Value Debt Securities, Available-for-Sale, Unrealized Loss Position, Fair Value [Table Text Block] Expiration Date Trading Arrangement Expiration Date Loans held for investment by Region [Line Items] Loans held for investment by Region [Line Items] [Line Items] for Loans held for investment by Region [Table] Decrease in other liabilities Increase (decrease) in other liabilities Increase (Decrease) in Other Operating Liabilities Seasoning based on monthly scheduled payments due from 13 - 24 payments Seasoning Based On Monthly Scheduled Payments Due From Thirteen To Twenty Four Payments In Percent Seasoning based on monthly scheduled payments due from thirteen to twenty four payments in percent. Premises and equipment, net Premises and equipment, net Property, Plant and Equipment, Net Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Restricted Cash Restricted Cash and Investments [Policy Text Block] Restricted Cash and Investments [Policy Text Block] Non-interest income (loss) Non-Interest Income (Loss) Non-Interest Income (Loss) Entity Current Reporting Status Entity Current Reporting Status Receivables [Abstract] Receivables [Abstract] Derivative [Line Items] Derivative [Line Items] Loans held for investment by Region [Table] Loans held for investment by Region [Table] Loans held for investment by Region [Table] Schedule of Maturities of Time Deposits Schedule of Maturities of Time Deposits [Table Text Block] Schedule of Maturities of Time Deposits [Table Text Block] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] ABS Transactions ABS Transactions [Member] ABS Transactions [Member] Collateral [Axis] Collateral Held [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Delinquent Private Education Loans in repayment as a percentage of Private Education Loans in repayment, Year 5 Delinquencies As Percentage Of Loans In Repayment, Originated Four Years Before Current Fiscal Year Delinquencies As Percentage Of Loans In Repayment, Originated Four Years Before Current Fiscal Year Statutory rate Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Common shares unissued but encumbered (in shares) Common Shares Unissued But Encumbered Common shares unissued but encumbered. Other interest-earning assets Other Interest Earning Assets Financial Instrument [Axis] Financial Instrument [Axis] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Executive Category: Executive Category [Axis] Granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Net of Forfeitures Gross Unrealized Losses Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Loans Held for Investment Financing Receivable [Policy Text Block] State tax, net of federal benefit Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent Other comprehensive income: Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract] Interest expense Interest Expense, Operating and Nonoperating Current Fiscal Year End Date Current Fiscal Year End Date Expected life of the option Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term Gross Unrealized Losses Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Deposits Total deposits Deposits Par value of mortgage-backed securities pledged to FRB Par Value Of Mortgage-Backed Securities Pledged To FRB Par Value Of Mortgage-Backed Securities Pledged To FRB Total change in other comprehensive income (loss) for unrealized gains (losses) on derivatives, before income tax (expense) benefit Change In Other Comprehensive Income (Loss) For Unrealized Gains (Losses) On Derivatives, Before Income Tax (Expense) Benefit Change In Other Comprehensive Income (Loss) For Unrealized Gains (Losses) On Derivatives, Before Income Tax (Expense) Benefit 700-749 FICO score 700-749 [Member] FICO score 700-749 [Member] Transfer from allowance for unfunded loan commitments Off-Balance Sheet, Credit Loss, Liability, Transfer From Unfunded Commitments Off-Balance Sheet, Credit Loss, Liability, Transfer From Unfunded Commitments Schedule of Loans Held for Investment Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Professional fees Professional Fees Common Equity Tier 1 Capital (to Risk-Weighted Assets) Tier One Common Equity Capital Required to be Well Capitalized to Risk Weighted Assets Tier One Common Equity Capital Required to be Well Capitalized to Risk Weighted Assets Weighted Average Grant Date Fair Value Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Schedule of Securities Financing Transactions Schedule of Securities Financing Transactions [Table Text Block] Derivative instruments Derivative values with impact of master netting agreements (as carried on balance sheet) Derivative instruments Derivative Liability Other operating expenses Other Noninterest Expense Weighted average fair value of stock purchase rights (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Net proceeds from sales of loans held for investment and loans held for sale Net Proceeds from Loans Held for Investment and Loans Held for Sale Net Proceeds from Loans Held for Investment and Loans Held for Sale Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Loan Restructuring Modification [Axis] Loan Restructuring Modification [Axis] Gross Unrealized Losses Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss Percent of brokered deposit Brokered Deposit, Percent Brokered Deposit, Percent 2038 Maturity 2038 [Member] Maturity 2038 [Member] Valuation of Financial Instruments that are Marked-to-market on Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Condensed Balance Sheet Statements, Captions [Line Items] Condensed Balance Sheet Statements, Captions [Line Items] Money-market and savings accounts Money Market and Savings Accounts [Member] Money Market and Savings Accounts [Member] Unrecognized tax benefits Unrecognized tax benefits at beginning of year Unrecognized tax benefits at end of year Unrecognized Tax Benefits Cash and Cash Equivalents [Abstract] Cash and Cash Equivalents [Abstract] Antidilutive securities excluded from computation of earnings per share, less than (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Total operating expenses Operating Expenses, Excluding Amortization Of Intangible Assets Operating Expenses, Excluding Amortization Of Intangible Assets Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Other Investments Securities Owned Not Readily Marketable, Policy [Policy Text Block] Stated maturity, 2027 Long-Term Debt, Maturity, Year Two Age Analysis of Past Due Loans Delinquencies Financing Receivable, Past Due [Table Text Block] Deposits - interest-bearing Deposits - interest-bearing Interest-Bearing Deposit Liabilities 2025-A ABS Transaction SMB Private Education Loan Trust 2025-A [Member] SMB Private Education Loan Trust 2025-A Net cash (used in) provided by financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Weighted Average Remaining Contractual Term Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Private Education Loans Private Education Loans Private Education Loans [Member] Private education loans. Measure: Measure [Axis] Valuation Approach and Technique [Axis] Valuation Approach and Technique [Axis] Dividends received from Sallie Mae Bank Proceeds from Dividends Received Well Capitalized Regulatory Requirements, Amount Banking Regulation, Tier 1 Leverage Capital [Abstract] Property, Plant and Equipment, Type [Domain] Long-Lived Tangible Asset [Domain] Average Balance Financing Receivable, Before Allowance For Credit Loss, Average Balance Financing Receivable, Before Allowance For Credit Loss, Average Balance Remaining authority under the share repurchase program Share Repurchase Program, Remaining Authorized, Amount Consumer Portfolio Segment Consumer Portfolio Segment [Member] Finance Receivable Transferred To Held For Sale [Line Items] Finance Receivable Transferred To Held For Sale [Line Items] Finance Receivable Transferred To Held For Sale [Line Items] Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Year-End Weighted Average Stated Rate Weighted Average Rate Domestic Deposit Liabilities [Abstract] Actual Amount Banking Regulation, Total Capital [Abstract] Total Allowance Percentage of Private Education Loan Exposure(5)(6) Allowance As Percentage Of Ending Loan Balance And Accrued Interest Allowance As Percentage Of Ending Loan Balance And Accrued Interest Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Risk-free interest rate Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Entity Tax Identification Number Entity Tax Identification Number Valuation Technique, Discounted Cash Flow Valuation Technique, Discounted Cash Flow [Member] Business credits Effective Income Tax Rate Reconciliation, Tax Credit, Percent Schedule of Variable Interest Entities Schedule of Variable Interest Entities [Table Text Block] Beginning balance (in dollars per share) Ending balance (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price Common stock, shares issued (in shares) Beginning balance, Common shares issued (in shares) Ending balance, Common shares issued (in shares) Common Stock, Shares, Issued Stated maturity, 2029 Long-Term Debt, Maturity, Year Four Effect of dilutive securities: Dilutive Securities, Effect on Basic Earnings Per Share [Abstract] Goodwill and Acquired Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Carrying Amount of Net Assets Securing Debt Outstanding Restricted Cash [Abstract] Without cosigner Without Cosigner [Member] Without Cosigner [Member] Allowance For Credit Losses [Abstract] Allowance For Credit Losses [Abstract] Allowance for credit losses. Allowance Allowance [Abstract] Allowance. Entity Public Float Entity Public Float Trading Arrangement: Trading Arrangement [Axis] Increase (decrease) in income tax payable, net Increase (Decrease) in Income Taxes Payable Total Shareholder Return Amount Total Shareholder Return Amount Trading - Residual Interests Retained Interest [Member] Security Exchange Name Security Exchange Name Number of additional shares authorized to be repurchased Stock Repurchase Program, Number of Additional Shares Authorized to be Repurchased Stock Repurchase Program, Number of Additional Shares Authorized to be Repurchased Nondeductible items Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amount Mortgage-backed securities Collateralized Mortgage-Backed Securities [Member] Common Equity Tier 1 Capital (to Risk-Weighted Assets) Tier One Common Equity Capital to Risk Weighted Assets Tier One Common Equity Capital to Risk Weighted Assets Secured borrowing facility maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Interest Expense Interest Expense, Policy [Policy Text Block] Non-interest expenses: Operating Expenses [Abstract] Asset Class [Domain] Asset Class [Domain] Private Education Loans deferred origination costs and unamortized premium/(discount), Year 1 Net Unamortized Premium Or Discount, Originated In Current Fiscal Year Net Unamortized Premium Or Discount, Originated In Current Fiscal Year Included in earnings (or changes in net assets) Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings Acquired intangible assets impairment and amortization expense Acquired intangible assets impairment and amortization expense Amortization of Acquired Intangible Assets, Including Impairment of Intangible Assets Amortization of Acquired Intangible Assets, Including Impairment of Intangible Assets Statement [Line Items] Statement [Line Items] Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Cash and cash equivalents Cash and cash equivalents Cash and cash equivalents at beginning of year Cash and cash equivalents at end of year Cash and Cash Equivalent Fair Value Measurement Inputs and Valuation Techniques [Table] Fair Value Measurement Inputs and Valuation Techniques [Table] Subsequent Event [Line Items] Subsequent Event [Line Items] Common Stock Common Stock [Member] Vested (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period Private Education Loans deferred origination costs and unamortized premium/(discount), Total Net Unamortized Premium Or Discount, Before Allowance For Credit Loss Net Unamortized Premium Or Discount, Before Allowance For Credit Loss Short-term borrowings Other Short-Term Borrowings Net (decrease) increase in cash, cash equivalents and restricted cash 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 and Discontinued Operation Total Private Education Loans, gross, Year 1 Loans Gross, Originated In Current Fiscal Year Loans Gross, Originated In Current Fiscal Year Measurement Input, Prepayment Rate Measurement Input, Prepayment Rate [Member] Common stock dividend per common share (in dollars per share) Common Stock, Dividends, Per Share, Cash Paid Significant Accounting Policies Significant Accounting Policies [Text Block] Statistical Measurement [Domain] Statistical Measurement [Domain] Schedule of Notional Amounts of Outstanding Derivative Positions Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block] Parent only Condensed Balance Sheets Condensed Balance Sheet [Table Text Block] Total Private Education Loans, gross, Year 3 Loans Gross, Originated Two Years Before Latest Fiscal Year Loans Gross, Originated Two Years Before Latest Fiscal Year Schedule of Loans Held for Investment by Region Loans held for investment by Region [Table Text Block] [Table Text Block] for Loans held for investment by Region [Table] Weighted Average Interest Rate Weighted Average Interest Rate on Loans Weighted Average Interest Rate on Loans Loan principal Financing receivable, sale, principal Financing Receivable Held For Sale, Principal Financing Receivable Held For Sale, Principal Short-term borrowings Short-Term Debt, Fair Value FICO Refreshed School FICO, Refreshed Amounts [Member] School FICO, Refreshed Amounts [Member] Weighted Average Interest Rate Long-Term Debt, Weighted Average Interest Rate, at Point in Time Asset Class [Axis] Asset Class [Axis] Total allowance for credit losses, ending balance Allowance for Credit Loss, Excluding Accrued Interest Allowance for Credit Loss, Excluding Accrued Interest Period of notification for withdrawal of deposits (less than or equal to) Deposits, Period of Notification for Withdrawal Deposits, Period of Notification for Withdrawal Valuation Approach and Technique [Domain] Valuation Approach and Technique [Domain] Interest rate swaps Interest Rate Swaps Interest Rate Swap [Member] Included in other comprehensive income Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) Numerator: Numerator [Abstract] Numerator. Increases resulting from tax positions taken during a prior period Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions 2021 Omnibus Incentive Plan 2021 Omnibus Incentive Plan [Member] 2021 Omnibus Incentive Plan Brokered deposit placement fee Cash Paid For Brokered Deposit Placement Fee Cash Paid For Brokered Deposit Placement Fee Retirement Plan Name [Axis] Retirement Plan Name [Axis] Shares repurchased related to employee stock-based compensation plans Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation Gross Unrealized Losses Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Basic earnings per common share (in usd per share) Earnings Per Share, Basic Total in percent Private Education Loans Gross, Percentage Private education loans gross in percent. Liabilities: Liabilities, Fair Value Disclosure [Abstract] Private Education Loans in forbearance, total Loans In Repayment, Before Allowance For Credit Loss Loans In Repayment, Before Allowance For Credit Loss Changes in unrecognized tax benefits Effective Income Tax Rate Reconciliation, Tax Contingency, Percent Tax benefit from exercise of stock options Share-Based Payment Arrangement, Exercise of Option, Tax Benefit Other comprehensive income (loss), net of tax (expense) benefit Other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax Schedule of Segment Reporting Information, by Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Short-Term Short-Term Debt After four years to five years Time Deposit Maturities, Year Five Increase in accrued interest receivable Increase (Decrease) in Accrued Interest Receivable, Net Deposits Deposits, Fair Value Disclosure Number of mortgage-backed securities Debt Securities, Available-for-sale, Number of Positions Debt Securities, Available-for-sale, Number of Positions Short-term borrowing, difference Short-Term Debt, Fair Value, Difference Between Carrying Value And Fair Value Short-Term Debt, Fair Value, Difference Between Carrying Value And Fair Value Measurement Input Type [Domain] Measurement Input Type [Domain] Schedule of Amortized Cost and Fair Value of Securities Available-for-Sale Schedule of Available-for-Sale Securities Reconciliation [Table Text Block] Allowance For Credit Card Loans Allowance For Credit Card Loans [Policy Text Block] Allowance For Credit Card Loans Change in unrealized gains or losses for the period included in earnings (or changes in net assets) for assets held at the end of the reporting period Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss) Cumulative Effect, Period of Adoption [Domain] Cumulative Effect, Period of Adoption [Domain] 670-699 FICO score 670-699 [Member] FICO score 670-699 [Member] Percentage of loans held in state Percentage of Loans held in state Percentage of Loans held in state Total accrued interest by origination vintage, Year 3 Financing Receivable, Accrued interest, Origination Vintage, Originated Two Years before Latest Fiscal Year Financing Receivable, Accrued interest, Origination Vintage, Originated Two Years before Latest Fiscal Year Charge-offs Current period recoveries, total Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Accrued interest receivable not expected to be capitalized Accrued Interest Receivable Not Expected To Be Capitalized Accrued Interest Receivable Not Expected To Be Capitalized Variable Interest Entity, Primary Beneficiary Variable Interest Entity, Primary Beneficiary [Member] Equity Interests Debt Securities, Trading, and Equity Securities, FV-NI Interest rate reduction Interest Rate Reduction, Percentage Interest Rate Reduction, Percentage Accounts and Financing Receivables [Table] Accounts and Financing Receivables [Table] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Hedging Designation [Domain] Hedging Designation [Domain] Goodwill and Intangible Assets Disclosure [Abstract] Fees paid on Secured Borrowing Facility Net Increase (Decrease) in Upfront Fee Paid on Secured Borrowings Net Increase (Decrease) in Upfront Fee Paid on Secured Borrowings With and without cosigners Cosigner [Member] Cosigner credit quality indicators that are developed and used internally by the company. Loans held for sale Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance Canceled (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures in Period Total liabilities and equity Liabilities and Equity Savings Weighted Average Rate Domestic Deposit, Savings Number of Options Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding [Roll Forward] Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [Table] Total Private Education Loans, Year 1 Loans, Originated In Current Fiscal Year Loans, Originated In Current Fiscal Year Total Private Education Loan provisions for credit losses Financing Receivable, Credit Loss, Expense (Reversal), Commitments Financing Receivable, Credit Loss, Expense (Reversal), Commitments 2027 Maturity 2027 [Member] Maturity 2027 Net decrease in loans held for investment and loans held for sale (other than loans acquired and originated, and loan sales) Net Decrease in Loans Held for Investment and Loans Held for Sale Net Decrease in Loans Held for Investment and Loans Held for Sale Accounting Policies [Abstract] Accounting Policies [Abstract] Trading investments received in consideration for loans sold Trading Investment Received in Consideration for Loans Sold Trading Investment Received in Consideration for Loans Sold Line of credit facility, expiration period Line of Credit Facility, Expiration Period Repayments of borrowings under Secured Borrowing Facility Repayments of Secured Debt Loans in nonaccrual status Loans in Nonaccrual Status Loans in Nonaccrual Status Current period net charge-offs, Year 2 Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery, Originated In Fiscal Year Before Latest Fiscal Year Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery, Originated In Fiscal Year Before Latest Fiscal Year Treasury Stock Treasury Stock, Common [Member] Fair value of shares vested Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Year 1 Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year Net charge-offs as a percentage of average loans in repayment Charge Offs As Percentage Of Average Loans In Repayment Charge offs as percentage of average loans in repayment. Pay vs Performance Disclosure [Line Items] Tier 1 Capital (to Average Assets) Banking Regulation, Tier 1 Leverage Capital Ratio, Well Capitalized, Minimum Total Interest Receivable Accrued Interest Receivable On Private Education Loans Accrued interest receivable on private education loans. Equity securities without readily determinable fair value, downward price adjustment, annual amount Equity Securities without Readily Determinable Fair Value, Downward Price Adjustment, Annual Amount Impairment, Intangible Asset, Finite-Lived, Statement of Income or Comprehensive Income [Extensible Enumeration] Impairment, Intangible Asset, Finite-Lived, Statement of Income or Comprehensive Income [Extensible Enumeration] Loan delinquent 90 days or greater past due 90 Days or Greater Past Due Financial Asset, Equal to or Greater than 90 Days Past Due [Member] Total investments in subsidiaries (primarily Sallie Mae Bank) Investment in Subsidiary Investment in Subsidiary Preferred stock liquidation preference (in dollars per share) Preferred Stock, Liquidation Preference Per Share Liabilities Liabilities Liabilities [Abstract] Total interest-bearing liabilities Financial Liabilities Fair Value Disclosure Total Private Education Loans sold Financing Receivable, Sale 2048 Maturity 2048 [Member] Maturity 2048 [Member] SMB Private Education Loan Trust 2025 SMB Private Education Loan Trust 2025 [Member] SMB Private Education Loan Trust 2025 Net charge-offs Current period net charge-offs, total Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff (Recovery) Asset balance related to securitization trust (as a percentage) Variable Interest Entities, Option to Exercise, Maximum Percentage of Assets to Original Loan Balance Variable Interest Entities, Option to Exercise, Maximum Percentage of Assets to Original Loan Balance Trading Activity, by Type [Domain] Trading Activity, by Type [Domain] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Impairment loss Goodwill, Impairment Loss Hedged items recorded in interest expense Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge Regulatory Capital Regulatory Capital Requirements under Banking Regulations [Text Block] Secured borrowings: Debt Instrument, Debt Default [Abstract] Less than 670 FICO score less than 670 [Member] FICO score less than 670 [Member] Year 3 Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Company Selected Measure Amount Company Selected Measure Amount Total Private Education Loans Loans, Before Allowance For Credit Loss Loans, Before Allowance For Credit Loss 2024-A ABS transaction SMB Private Education Loan Trust 2024-A [Member] SMB Private Education Loan Trust 2024-A Tier 1 Capital (to Risk-Weighted Assets) Banking Regulation, Tier 1 Risk-Based Capital Ratio, Well Capitalized, Minimum Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Total comprehensive income Total comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Private Education Loans deferred origination costs and unamortized premium/(discount), Year 6 Net Unamortized Premium Or Discount, Originated Five Or More Years Before Latest Fiscal Year Net Unamortized Premium Or Discount, Originated Five Or More Years Before Latest Fiscal Year Measurement Input Type [Axis] Measurement Input Type [Axis] Name Measure Name Secured borrowings: Line of Credit Facility [Abstract] Secured borrowings Secured Debt [Member] Class of Stock [Line Items] Class of Stock [Line Items] Interest Rate Reduction Interest Rate Below Market Reduction [Member] Unsecured Debt Unsecured borrowings Unsecured Debt [Member] Private Education Loans, net, Year 1 Financing Receivable, after Allowance for Credit Loss, Originated In Current Fiscal Year Financing Receivable, after Allowance for Credit Loss, Originated In Current Fiscal Year Financing Receivable, Modified, Subsequent Default Financing Receivable, Modified, Subsequent Default [Table Text Block] Long-term borrowings Long-Term Long-Term Debt Vertical risk retention interest Vertical Risk Retention, Percentage Vertical Risk Retention, Percentage Total assets Total Assets Parent only Condensed Statements of Cash Flows Condensed Cash Flow Statement [Table Text Block] Loan reserves Deferred Tax Asset, Tax Deferred Expense, Reserve and Accrual, Financing Receivable, Allowance for Credit Loss Expected amortization of 2026 Finite-Lived Intangible Asset, Expected Amortization, Year One Vested (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Geographical [Domain] Geographical [Domain] Seasoning based on monthly scheduled payments due from 25 - 36 payments Seasoning Based On Monthly Scheduled Payments Due From Twenty Five To Thirty Six Payments In Percent Seasoning based on monthly scheduled payments due from thirteen to twenty four payments in percent Income Taxes Income Tax, Policy [Policy Text Block] Combination of subsidiaries Combination Of Subsidiaries Tax Years Combination of subsidiaries tax years. Financing Receivable, Allowance for Credit Loss [Roll Forward] Financing Receivable, Allowance for Credit Loss [Roll Forward] Operating activities Cash flows from operating activities: Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Research credit Effective Income Tax Rate Reconciliation, Tax Credit, Research, Percent Weighted average useful life of acquired intangible assets Acquired Finite-Lived Intangible Assets, Weighted Average Useful Life Delinquent Private Education Loans in repayment as a percentage of Private Education Loans in repayment, Year 2 Delinquencies As Percentage Of Loans In Repayment, Originated In Fiscal Year Before Latest Fiscal Year Delinquencies As Percentage Of Loans In Repayment, Originated In Fiscal Year Before Latest Fiscal Year Amortization of deferred loan origination costs and loan premium/(discounts), net Amortization of Deferred Loan Origination Fees, Net Total Private Education Loans, Year 6 Loans, Originated Five Or More Years Before Latest Fiscal Year Loans, Originated Five Or More Years Before Latest Fiscal Year Assets: Assets, Fair Value Disclosure [Abstract] Current period net charge-offs, Year 3 Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery, Originated Two Years Before Current Fiscal Year Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery, Originated Two Years Before Current Fiscal Year After one year to two years Time Deposit Maturities, Year Two Credit Score, FICO [Axis] Credit Score, FICO [Axis] Undistributed earnings of subsidiaries Undistributed earnings of subsidiaries Undistributed earnings of subsidiaries Consolidation and Variable Interest Entities ("VIEs") Consolidation, Variable Interest Entity, Policy [Policy Text Block] Declared dividends per common share (in dollars per share) Common stock dividend (in dollars per share) Common Stock, Dividends, Per Share, Declared Other investments Other Investments Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-Sale [Line Items] Cash collateral held relative to derivative exposure Derivative, Cash Collateral Held Relative to Derivative Exposure, Net Derivative, Cash Collateral Held Relative to Derivative Exposure, Net Adjustments Cumulative Effect, Period of Adoption, Adjustment [Member] Threshold period when delinquent loans are written off Threshold Period Past Due For Write-off Of Financing Receivable Threshold Period Past Due For Write-off Of Financing Receivable Level 2  Fair Value, Inputs, Level 2 [Member] Document Financial Statement Error Correction [Flag] Document Financial Statement Error Correction [Flag] State and local income taxes, net of federal effect Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount 60 Days or Greater Past Due Financial Asset, Equal To Or Greater Than 60 Days Past Due [Member] Financial Asset, Equal To Or Greater Than 60 Days Past Due Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Average loans in repayment Allowance Coverage Of Charge Offs Average Loans In Repayment Allowance coverage of charge offs average loans in repayment. Business Combination [Domain] Business Combination [Domain] Components of Provision for Income Tax Expense (Benefit) Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Plan Name [Axis] Plan Name [Axis] Document Information [Table] Document Information [Table] PEO PEO [Member] Transfers into level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 Borrowings under Secured Borrowing Facility Proceeds from Issuance of Secured Debt Tier 1 Capital (to Average Assets) Banking Regulation, Tier 1 Leverage Capital, Actual Schedule of Amortized Cost and Fair Value of Securities by Contractual Maturities Investments Classified by Contractual Maturity Date [Table Text Block] Trading investments at fair value (cost of $37,606 and $41,715, respectively) Trading investments Debt Securities, Trading Supplemental non-cash operating and investing activities: Noncash Investing and Financing Items [Abstract] 2052 Maturity 2052 [Member] Maturity 2052 Income Tax Paid, by Individual Jurisdiction [Line Items] Income Tax Paid, by Individual Jurisdiction [Line Items] Credit Cards Credit Cards [Member] Credit Cards [Member] Changes in valuation allowances Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount Allowance for loan losses coverage of net charge-offs Annualized Allowance On Private Education Loan Coverage Of Charge Offs Annualized allowance on private education loan coverage of charge offs. Fixed assets Deferred Tax Liabilities, Property, Plant and Equipment Expected volatility Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate Total Time Deposits Retained Earnings Retained Earnings [Member] Income Tax Jurisdiction [Axis] Income Tax Jurisdiction [Axis] Average contractual rate Financing Receivable, Change in Contractual Rate Financing Receivable, Change in Contractual Rate Share-based Payment Arrangement [Abstract] Share-Based Payment Arrangement [Abstract] Cash, cash equivalents and restricted cash at beginning of year Cash, cash equivalents and restricted cash at end of year Total cash, cash equivalents and restricted cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Income Statement [Abstract] Income Statement [Abstract] Derivative values with impact of master netting agreements (as carried on balance sheet) Derivative instruments Derivative Asset Estimated Fair Value Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer Total Private Education Loans in forbearance, Year 5 Loans In Repayment, Originated Four Years Before Current Fiscal Year Loans In Repayment, Originated Four Years Before Current Fiscal Year Available-for-sale investments Investments, Fair Value Disclosure Increase (decrease) in accrued interest payable Increase (Decrease) in Interest Payable, Net Percent of total notional derivative contracts Derivative Instrument, Percent of Total Notional Derivative Contracts Derivative Instrument, Percent of Total Notional Derivative Contracts Provision Off-Balance-Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal) 12 months or more Debt Securities, Available-for-Sale [Abstract] Debt Securities, Available-for-Sale [Abstract] Net income Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Brokered deposits Brokered Deposits Brokered Deposits Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Business Combination [Table] Business Combination [Table] Notional derivative contracts Notional value Notional Values Derivative, Notional Amount Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Percentage of Private Education Loans in repayment, Year 3 Percentage Of Loans In Repayment, Originated Two Years Before Latest Fiscal Year Percentage Of Loans In Repayment, Originated Two Years Before Latest Fiscal Year Income Tax Paid, by Individual Jurisdiction [Table] Income Tax Paid, by Individual Jurisdiction [Table] Number of active stock-based compensation plans Number of Compensation Plans Number of Compensation Plans Delinquent Private Education Loans in repayment as a percentage of Private Education Loans in repayment, total Delinquencies As Percentage Of Loans In Repayment Delinquencies as a percentage of loans in repayment. City Area Code City Area Code Schedule of Allowance for Credit Losses and Recorded Investments in Loans Financing Receivable, Allowance for Credit Loss [Table Text Block] Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Accrued interest capitalized during the period Interest Costs Capitalized Loan Interest Income Financing Receivable, Fee and Interest Income [Policy Text Block] Investing activities Cash flows from investing activities: Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Loans sold Financing Receivable And Off-Balance Sheet, Excluding Accrued Interest, Before Allowance For Credit Loss, Loan Sold Financing Receivable And Off-Balance Sheet, Excluding Accrued Interest, Before Allowance For Credit Loss, Loan Sold Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Provision/New commitments - net Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability, Additional Commitments Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability, Additional Commitments Accrued interest receivable Interest Receivable Fair Value Fair Value Hedging [Member] 2020 Share Repurchase Program 2020 Share Repurchase Program [Member] 2020 Share Repurchase Program Investment Program, Proportional Amortization Method, Elected, Income Tax Credit and Other Income Tax Benefit, before Amortization, Statement of Cash Flows [Extensible Enumeration] Investment Program, Proportional Amortization Method, Elected, Income Tax Credit and Other Income Tax Benefit, before Amortization, Statement of Cash Flows [Extensible Enumeration] Credit Quality Indicators [Domain] Credit Quality Indicators [Domain] Credit Quality Indicators [Domain] Cash Flow Cash Flow Hedging [Member] Goodwill Goodwill Other liabilities Other Liabilities Audit Information [Abstract] Audit Information [Abstract] Financing receivable, ,modified in period, amount Financing Receivable, Modified in Period, Amount Income taxes receivable, net Income Taxes Receivable U.S. Federal Deferred Federal Income Tax Expense (Benefit) Gains (losses) on securities, net (Gains) losses on securities, net Gain (Loss) on Sales of Mortgage-Backed Securities (MBS) Transfers out of level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 Unrecognized Tax Benefits [Roll Forward] Unrecognized Tax Benefits [Roll Forward] 2056 Maturity 2056 [Member] Maturity 2056 Denominator: Denominator [Abstract] Denominator [Abstract] Auditor Name Auditor Name Schedule of Amortized Cost Basis of Financing Receivables Financing Receivables, Amortized Cost Basis [Table Text Block] Financing Receivables, Amortized Cost Basis Retail and other deposits Retail and Other Deposits Retail and Other Deposits Private Education Loan term securitizations: Private Education Loan Securitization [Member] Private Education Loan Securitization [Member] Period of loans past due that have accrued interest Period of Loans Past Due That Have Accrued Interest Period of Loans Past Due That Have Accrued Interest Cash disbursements made for: Supplemental Cash Flow Information [Abstract] Operating loss carryforwards, valuation allowance Operating Loss Carryforwards, Valuation Allowance Available-for sale investments at fair value, cost Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost Other Performance Measure, Amount Other Performance Measure, Amount Weighted Average Exercise Price per Share Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] 2049 Maturity 2049 [Member] Maturity 2049 [Member] Issuance costs for Borrowings Payments of Debt Issuance Costs Total accrued interest by origination vintage, Year 2 Financing Receivable, Accrued Interest, Origination Vintage, Originated in Fiscal Year before Latest Fiscal Year Financing Receivable, Accrued Interest, Origination Vintage, Originated in Fiscal Year before Latest Fiscal Year Dividends Dividends Income Tax Expense (Benefit), Effective Income Tax Rate Reconciliation, Amount [Abstract] Income Tax Expense (Benefit), Effective Income Tax Rate Reconciliation, Amount [Abstract] Income taxes refunded Proceeds from Income Tax Refunds Derivative Instrument [Axis] Derivative Instrument [Axis] Fair Value Measurement Fair Value of Financial Instruments, Policy [Policy Text Block] Interest-bearing liabilities: Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract] Deferred origination costs and unamortized premium/ (discount) Financing Receivable, Unamortized Loan Cost (Fee) and Purchase Premium (Discount) Investments: Investments [Abstract] Total Private Education Loans in forbearance, Year 4 Financing Receivable, Loans In Forbearance, Year Four, Originated, Three Years before Current Fiscal Year Financing Receivable, Loans In Forbearance, Year Four, Originated, Three Years before Current Fiscal Year Total net cash provided by (used in) investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Percentage of Private Education Loans in repayment Percentage Of Loans In Repayment, Before Allowance For Credit Loss Percentage Of Loans In Repayment, Before Allowance For Credit Loss Total accrued interest by origination vintage, Year 5 Financing Receivable, Accrued interest, Origination Vintage, Originated Four Years before Latest Fiscal Year Financing Receivable, Accrued interest, Origination Vintage, Originated Four Years before Latest Fiscal Year Current period recoveries, Year 5 Financing Receivable, Allowance for Credit Loss, Recovery, Originated Four Years Before Current Fiscal Year Financing Receivable, Allowance for Credit Loss, Recovery, Originated Four Years Before Current Fiscal Year Interest Interest Paid, Excluding Capitalized Interest, Operating Activity Document Fiscal Year Focus Document Fiscal Year Focus Available-for-sale investments received in consideration for loans sold Available-For-Sale Investments Received in Consideration for Loans Sold Available-For-Sale Investments Received in Consideration for Loans Sold Effective tax rate Effective Income Tax Rate Reconciliation, Percent Decreases resulting from tax positions taken during a prior period Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Loans Held for Sale Loans Held For Sale [Policy Text Block] Loans Held For Sale Carrying Value Reported Value Measurement [Member] Plan Name [Domain] Plan Name [Domain] Acquisition related costs Business Combination, Acquisition-Related Cost, Expense Weighted average period for total unrecognized compensation cost Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Net charge-offs: Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery [Abstract] Exercised (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period Equity Equity [Abstract] Goodwill and Acquired Intangible Assets Goodwill and Intangible Assets, Policy [Policy Text Block] Derivative Accounting Derivatives, Policy [Policy Text Block] Segment Reporting Segment Reporting Disclosure [Text Block] Fair Value Measurements on a Recurring Basis Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Delinquent Private Education Loans in repayment as a percentage of Private Education Loans in repayment, Year 3 Delinquencies As Percentage Of Loans In Repayment, Originated Two Years Before Current Fiscal Year Delinquencies As Percentage Of Loans In Repayment, Originated Two Years Before Current Fiscal Year U.S. Federal Current Federal Tax Expense (Benefit) Technology expenses Information Technology and Data Processing Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Less than 12 months Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss [Abstract] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Other securities Other Debt Obligations [Member] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Weighted Average Weighted Average [Member] Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Amortized intangible assets Amortization of Intangible Assets Maximum amount of forbearance granted Financing Receivable, Month Limit On Forbearance Granted, Life Of Loan Financing Receivable, Month Limit On Forbearance Granted, Life Of Loan Debt Securities Debt Securities, Available-for-Sale, Measurement Input Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Preferred stock dividend rate (in dollars per share) Preferred Stock, Dividend Rate, Per-Dollar-Amount Unrecorded tax benefits Deferred Tax Assets, Tax Deferred Expenses, Reserves and Accruals, Unrecorded Tax Benefits Deferred Tax Assets, Tax Deferred Expenses, Reserves and Accruals, Unrecorded Tax Benefits More than 48 payments Seasoning Based On Monthly Scheduled Payments Due From More Than Forty Eight Payments [Member] Seasoning Based On Monthly Scheduled Payments Due From More Than Forty Eight Payments [Member] Performance Vesting Stock Options Performance Vesting Stock Options [Member] Performance Vesting Stock Options [Member] Arrangement Duration Trading Arrangement Duration Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Decrease in other interest-earning assets Payments for (Proceeds from) Other Interest Earning Assets Segments [Axis] Segments [Axis] Actual Ratio Banking Regulation, Risk-Based Information [Abstract] Private Education Loans, net, Year 5 Financing Receivable, after Allowance for Credit Loss, Originated Four Years Before Current Fiscal Year Financing Receivable, after Allowance for Credit Loss, Originated Four Years Before Current Fiscal Year Fair Value by Liability Class [Domain] Fair Value by Liability Class [Domain] Local Phone Number Local Phone Number Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Due from subsidiaries, net Due from Subsidiares, Net Due from Subsidiares, Net Share price (in dollars per share) Share Price Stated maturity, 2031 and after Long-Term Debt, Maturity, after Year Five Stock-Based Compensation Plans and Arrangements Share-Based Payment Arrangement [Text Block] Common stock repurchased (in shares) Stock Repurchased and Retired During Period, Shares Identifiable intangible assets at acquisition date included definite life intangible assets Business Combination, Recognized Asset Acquired, Identifiable Intangible Asset, Excluding Goodwill Loans in forbearance as a percentage of loans in repayment and forbearance, Year 4 Loans in forbearance as a percentage of Private Education Loans in repayment and forbearance, Originated Three Years Before Current Fiscal Year Loans in forbearance as a percentage of Private Education Loans in repayment and forbearance, Originated Three Years Before Current Fiscal Year Accrued interest receivable Accrued Interest Receivable, Fair Value Disclosure Accrued Interest Receivable, Fair Value Disclosure Beginning balance Ending balance Off-Balance-Sheet, Credit Loss, Liability Off-Balance-Sheet, Credit Loss, Liability Loans In Forbearance Loans In Forbearance [Member] Loans In Forbearance Assets Assets Assets [Abstract] Number of payments required by a borrower between successive grants of forbearance Financing Receivable, Number Of Payments Required Between Forbearance Grants Financing Receivable, Number Of Payments Required Between Forbearance Grants Unsecured Borrowings - issued, net of discount and underwriting fees Proceeds from Issuance of Unsecured Debt Credit Facility [Axis] Credit Facility [Axis] Unrealized gains (losses) on investments OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment, before Tax Private Education Loans allowance for losses, Year 3 Financing Receivable, Allowance For Credit Loss, Originated Two Years Before Current Fiscal Year Financing Receivable, Allowance For Credit Loss, Originated Two Years Before Current Fiscal Year Underlying Security Market Price Change Underlying Security Market Price Change, Percent Debt Instrument [Axis] Debt Instrument [Axis] Fair Value Measurements Fair Value Disclosures [Text Block] Loss on early extinguishment of Unsecured Borrowings Gain (Loss) on Extinguishment of Debt Credit Quality Indicators [Axis] Credit Quality Indicators [Axis] Credit Quality Indicators [Axis] Fixed-rate Fixed-rate Fixed Income Interest Rate [Member] Business Combination [Line Items] Business Combination [Line Items] Credit Facility [Domain] Credit Facility [Domain] Equity Equity, Attributable to Parent [Abstract] Issuance of common shares Stock Issued During Period, Value, New Issues Including Dividend Equivalents Stock Issued During Period, Value, New Issues Including Dividend Equivalents Payment for delivery of common stock Treasury Stock, Value, Acquired, Cost Method Fair Value Hedges Effect of Fair Value Hedges on Results of Operations [Abstract] Private Education Loans at origination Private Education Loans At Origination Private Education Loans At Origination Interest rate Debt Instrument, Interest Rate, Stated Percentage Loan delinquent 30-59 days 30-59 Days Past Due Financial Asset, 30 to 59 Days Past Due [Member] Entity Voluntary Filers Entity Voluntary Filers Sallie.com domain Sallie.com Domain [Member] Sallie.com Domain Secured Borrowings - issued, net of discount and deferred fees Borrowings Issues, Discount And Deferred Fees, Net Borrowings Issues, Discount And Deferred Fees, Net Gross position Derivative Asset, Subject to Master Netting Arrangement, before Offset Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Abstract] Entity Registrant Name Entity Registrant Name Common stock, par value $.20 per share Common stock, par value $.20 per share [Member] Common stock, par value $.20 per share Gain (loss) to be reclassified within 12 months Cash Flow Hedge Gain (Loss) to be Reclassified within 12 Months SMB Private Education Loan Trust 2020-PTA and 2020-PTB SMB Private Education Loan Trust 2020-PTA and 2020-PTB [Member] SMB Private Education Loan Trust 2020-PTA and 2020-PTB Retirement Plan Name [Domain] Retirement Plan Name [Domain] Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Total Capital (to Risk-Weighted Assets) Banking Regulation, Total Risk-Based Capital Ratio, Well Capitalized, Minimum Allowance For FFELP Loan Losses Allowance For FFELP Loan Losses, Policy [Policy Text Block] Allowance For FFELP Loan Losses, Policy Trading Activity [Axis] Trading Activity [Axis] Total Total Assets, Fair Value Disclosure Number of government sponsored securities with unrealized losses Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions Deposits [Abstract] Deposits [Abstract] Ending loans in repayment Allowance Coverage Of Charge Offs Ending Loans In Repayment Allowance coverage of charge-offs Ending loans in repayment. Percent of private education loans related to borrowers in school, grace or deferment Percentage Of Private Education Loans Related To Borrowers In School, Grace or Deferment Percentage Of Private Education Loans Related To Borrowers In School, Grace or Deferment Net amortization of discount on investments Accretion (Amortization) of Discounts and Premiums, Investments Schedule of Secured Borrowings Schedule of Debt [Table Text Block] Total Private Education Loans, gross Loans Gross, Before Allowance For Credit Loss Loans Gross, Before Allowance For Credit Loss % of Total Class of Financing Receivable Loan Modifications Made to Borrowers Experiencing Financial Difficulty, Percentage Loan Modifications Made to Borrowers Experiencing Financial Difficulty, Percentage Granted (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value 2026 Share Repurchase Program 2026 Share Repurchase Program [Member] 2026 Share Repurchase Program Cumulative Effect, Period of Adoption [Axis] Cumulative Effect, Period of Adoption [Axis] Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Percentage of Private Education Loans in repayment, Year 4 Percentage Of Loans In Repayment, Originated Three Years Before Latest Fiscal Year Percentage Of Loans In Repayment, Originated Three Years Before Latest Fiscal Year Schedule of Acquired Intangible Assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Restatement Determination Date: Restatement Determination Date [Axis] Expired capital losses Effective Income Tax Rate Reconciliation, Tax Credit, Expired Capital Losses, Percent Effective Income Tax Rate Reconciliation, Tax Credit, Expired Capital Losses, Percent Research and development costs Deferred Tax Liabilities, Deferred Expense, Capitalized Research and Development Costs Loans in forbearance as a percentage of loans in repayment and forbearance, Year 3 Loans in forbearance as a percentage of Private Education Loans in repayment and forbearance, Originated Two Years Before Current Fiscal Year Loans in forbearance as a percentage of Private Education Loans in repayment and forbearance, Originated Two Years Before Current Fiscal Year Loans in forbearance as a percentage of loans in repayment and forbearance Loans in forbearance as a percentage of Private Education Loans in repayment and forbearance Loans in forbearance as a percentage of Private Education Loans in repayment and forbearance Reportable Segment Reportable Segment [Member] Reportable Segment Name Trading Arrangement, Individual Name Cash dividends declared: Dividends, Cash [Abstract] Schedule of Short-term Debt [Table] Short-Term Debt [Table] Period-end Amortized Cost Basis Financing Receivable, Modified, Subsequent Default Loans held for sale Loan, Held-for-Sale, Fair Value Disclosure 13-24 payments Seasoning Based On Monthly Scheduled Payments Due From Thirteen To Twenty Four Payments [Member] Seasoning Based On Monthly Scheduled Payments Due From Thirteen To Twenty Four Payments [Member] Total Private Education Loans in forbearance, Year 6 Financing Receivable, Loans In Forbearance, Year Six, Originated, More Than Six Years before Current Fiscal Year Financing Receivable, Loans In Forbearance, Year Six, Originated, More Than Six Years before Current Fiscal Year Total Private Education Loans, Year 3 Loans, Originated Two Years Before Current Fiscal Year Loans, Originated Two Years Before Current Fiscal Year Transfer to allowance for loan losses Transfer - funded loans Off-Balance Sheet, Credit Loss, Liability, Writeoff Off-Balance Sheet, Credit Loss, Liability, Writeoff Notes Issued Debt Instrument, Face Amount Percentage of Private Education Loans in repayment, Year 1 Percentage Of Loans In Repayment, Originated In Current Fiscal Year Percentage Of Loans In Repayment, Originated In Current Fiscal Year Deposits Deposits [Member] Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Amortization cost basis Financing Receivable, Modified in Period, Subsequently Charged Off, Amount Financing Receivable, Modified in Period, Subsequently Charged Off, Amount Amortization of fees for Secured Borrowing Facility Amortization of issuance costs for Unsecured Borrowings Amortization of ABCP Unsecured Borrowings Amortization of ABCP Unsecured Borrowings Share Repurchase Program [Axis] Share Repurchase Program [Axis] Preferred Stock Preferred Stock [Member] Total Private Education Loans in forbearance, Year 1 Loans In Repayment, Originated In Current Fiscal Year Total loans in repayment. Name Awards Close in Time to MNPI Disclosures, Individual Name Loss before income tax expense (benefit) and equity in net income from subsidiaries Income (Loss) From Continuing Operations Before Income (loss) From Subsidiaries and Income Taxes Income (Loss) From Continuing Operations Before Income (loss) From Subsidiaries and Income Taxes Beginning balance (in dollars per share) Ending balance (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Schedule of Restricted Stock Unit and Performance Stock Unit Activity Schedule Of Share Based Compensation Arrangement By Share Based Payment Award Restricted Stock Units And Performance Stock Units Vested And Expected To Vest Table [Table Text Block] Schedule Of Share Based Compensation Arrangement By Share Based Payment Award Restricted Stock Units And Performance Stock Units Vested And Expected To Vest [Table Text Block] Federal deferred for state receivable Deferred Tax Liabilities, Federal Deferred for State Receivable Deferred Tax Liabilities, Federal Deferred for State Receivable ICFR Auditor Attestation Flag ICFR Auditor Attestation Flag Employer matching contribution percentage Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay Number of central counterparties Number Of Counterparties Number Of Counterparties Outstanding cash equivalents Cash Equivalents, at Carrying Value Other All Other States [Member] All Other States Stock-based compensation expense APIC, Share-Based Payment Arrangement, Increase for Cost Recognition 2026 Maturity 2026 [Member] Maturity 2026 Defined Contribution Plan Disclosure [Line Items] Defined Contribution Plan Disclosure [Line Items] Parent only Condensed Statements of Income Condensed Income Statement [Table Text Block] Liability Class [Axis] Liability Class [Axis] Auditor Firm ID Auditor Firm ID Segments [Domain] Segments [Domain] Statement of Income Location, Balance [Axis] Statement of Income Location, Balance [Axis] Investments Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Total Private Education Loans, gross, Year 5 Loans Gross, Originated Four Years Before Latest Fiscal Year Loans Gross, Originated Four Years Before Latest Fiscal Year Percentage reimbursement on all qualifying default claims period one (as a percentage) Percentage Reimbursement On All Qualifying Default Claims Period One Percentage reimbursement on all qualifying default claims period one. Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy and NAV [Domain] Secured borrowings outstanding Line of Credit, Current Private Education Loans allowance for losses, Year 5 Financing Receivable, Allowance For Credit Loss, Originated Four Years Before Current Fiscal Year Financing Receivable, Allowance For Credit Loss, Originated Four Years Before Current Fiscal Year Other Assets Derivative Asset [Abstract] Low-income housing credit Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent Interest expense: Interest Expense, Operating and Nonoperating [Abstract] Accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Delinquent Private Education Loans in repayment as a percentage of Private Education Loans in repayment, Year 4 Delinquencies As Percentage Of Loans In Repayment, Originated Three Years Before Current Fiscal Year Delinquencies As Percentage Of Loans In Repayment, Originated Three Years Before Current Fiscal Year Percentage of loans concentrated in major states Percentage of loans concentrated in major states Percentage of Loans concentrated in major states Percentage of Loans concentrated in major states Equity in net income from subsidiaries (primarily Sallie Mae Bank) Income (Loss) from Subsidiaries, Net of Tax Purchases of available-for-sale securities Payments to Acquire Debt Securities, Available-for-Sale Series B: 2.5 million and 2.5 million shares issued, respectively, at stated value of $100 per share Preferred Stock, Value, Issued Monthly payment that is smaller than the interest accrued on the loan in that month Fixed-Pay Loan, Monthly Payment Amount, Below Monthly Accrued Interest Fixed-Pay Loan, Monthly Payment Amount, Below Monthly Accrued Interest Defined Contribution Plan [Table] Defined Contribution Plan [Table] Year 2 Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year Money market Weighted Average Rate Domestic Deposit, Money Market Brokered CDs Brokered Deposits [Member] Brokered Deposits [Member] Financial Asset, Period Past Due [Axis] Financial Asset, Aging [Axis] All Executive Categories All Executive Categories [Member] Schedule of Deferred Tax Assets and Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Common stock, par value $0.20 per share, 1.125 billion shares authorized: 443.2 million and 440.6 million shares issued, respectively Common stock, par value $0.20 per share, 1.125 billion shares authorized: 443.2 million and 440.6 million shares issued, respectively Common Stock, Value, Issued Time Deposits, Fiscal Year Maturity [Abstract] Time Deposits, Fiscal Year Maturity [Abstract] Loans Interest and Fee Income, Loans and Leases Derivatives recorded in interest expense Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments Gain (loss) on sale of loan and leases Gain (Loss) on Sale of Loans and Leases Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Accrued interest receivable expected to be capitalized reserved Accrued Interest Receivable Expected To Be Capitalized Reserved Allowance For Credit Losses Accrued Interest Receivable Expected To Be Capitalized Reserved Allowance For Credit Losses Commitments and contingencies Commitments and Contingencies Lendable value of collateral Lendable value of collateral Lendable value of collateral Business Combination [Axis] Business Combination [Axis] Cash and cash equivalents Cash And Investments Interest Income Loss Cash and investments interest income (loss). Schedule of Restricted Stock Activity Schedule of Nonvested Share Activity [Table Text Block] Investment Program, Proportional Amortization Method, Elected, Income Tax Credit and Other Income Tax Benefit, before Amortization, Statement of Income or Comprehensive Income [Extensible Enumeration] Investment Program, Proportional Amortization Method, Elected, Income Tax Credit and Other Income Tax Benefit, before Amortization, Statement of Income or Comprehensive Income [Extensible Enumeration] Interest Income - Investments Interest Income [Member] Short-term Debt [Line Items] Short-Term Debt [Line Items] Private Education Loans deferred origination costs and unamortized premium/(discount), Year 5 Net Unamortized Premium Or Discount, Originated Four Years Before Current Fiscal Year Net Unamortized Premium Or Discount, Originated Four Years Before Current Fiscal Year Deferred Tax Assets, Net Net deferred tax assets Deferred Tax Assets, Net PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Loans pledged as collateral, capitalized interest Loans Pledged As Collateral, Capitalized Interest Loans Pledged As Collateral, Capitalized Interest Carrying Amount of the Hedged Assets/(Liabilities) Hedged Liability, Fair Value Hedge Current period recoveries, Year 4 Financing Receivable, Allowance for Credit Loss, Recovery, Originated Three Years Before Current Fiscal Year Financing Receivable, Allowance for Credit Loss, Recovery, Originated Three Years Before Current Fiscal Year Loan delinquent 60-89 days 60-89 Days Past Due Financial Asset, 60 to 89 Days Past Due [Member] 2045 Maturity 2045 [Member] Maturity 2045 [Member] Loans in forbearance as a percentage of loans in repayment and forbearance, Year 6 Loans in forbearance as a percentage of Private Education Loans in repayment and forbearance, Originated Five Or More Years Before Current Fiscal Year Loans in forbearance as a percentage of Private Education Loans in repayment and forbearance, Originated Five Or More Years Before Current Fiscal Year Amortization of brokered deposit placement fee Amortization of Brokered Deposit Placement amortization of brokered deposit placement Hedging Designation [Axis] Hedging Designation [Axis] Loans in forbearance as a percentage of loans in repayment and forbearance, Year 2 Loans in forbearance as a percentage of Private Education Loans in repayment and forbearance, Originated In Fiscal Year Before Latest Fiscal Year Loans in forbearance as a percentage of Private Education Loans in repayment and forbearance, Originated In Fiscal Year Before Latest Fiscal Year Summary of Changes in Unrecognized Tax Benefits Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] Unfunded Commitments Unfunded Commitments [Abstract] Unfunded Commitments Net position Derivative Liability, Including Not Subject to Master Netting Arrangement, after Offset and Deduction California CALIFORNIA Less: Amount of gain (loss) reclassified in interest expense Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax Derivative Contract [Domain] Derivative Contract [Domain] Financing Receivable, Allowance for Credit Loss [Table] Financing Receivable, Allowance for Credit Loss [Table] Vesting period Share-Based Compensation Arrangement by Share-Based Payment Award, Award Requisite Service Period Debt Outstanding Debt Instruments [Abstract] All Individuals All Individuals [Member] Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Other Income Other Income Policy [Policy Text Block] Other income. Name Forgone Recovery, Individual Name Unrealized (gains) losses on derivative and hedging activities, net Unrealized Gain (Loss) on Derivatives Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Reclassification out of Accumulated Other Comprehensive Income Reclassification out of Accumulated Other Comprehensive Income [Member] Average Balance Long Term Debt, Weighted Average Outstanding Balance Long Term Debt, Weighted Average Outstanding Balance Loans in forbearance as a percentage of loans in repayment and forbearance, Year 5 Loans in forbearance as a percentage of Private Education Loans in repayment and forbearance, Originated Four Years Before Current Fiscal Year Loans in forbearance as a percentage of Private Education Loans in repayment and forbearance, Originated Four Years Before Current Fiscal Year Reconciliation of the Consolidated Statements of Cash Flows to the Consolidated Balance Sheets: Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation [Abstract] Share-based compensation arrangement by share-based payment award, purchase price of common stock, percent Share-Based Compensation Arrangement by Share-Based Payment Award, Purchase Price of Common Stock, Percent Weighted Average Cost of Funds Derivative, Basis Spread on Variable Rate LCH London Clearing House [Member] London Clearing House [Member] Proceeds from FFELP Loan claim payments Proceeds from Claim Payments Proceeds from Claim Payments Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Intangible Asset, Finite-Lived [Table] Intangible Asset, Finite-Lived [Table] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Geographical [Axis] Geographical [Axis] Tax benefit on accumulated other comprehensive loss Tax benefit on accumulated other comprehensive loss AOCI Tax, Attributable to Parent Schedule of Cumulative Basis Adjustments for Fair Value Hedges Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block] Other Liabilities Derivative Liability [Abstract] 2047 Maturity 2047 [Member] Maturity 2047 [Member] Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Allowance for Private Education Loan Losses and Key Credit Quality Indicators - Private Education Loans Allowance For Private Education Loan Losses Policy [Policy Text Block] Allowance for private education loan losses. Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Title of 12(b) Security Title of 12(b) Security Provision for current period Financing Receivable, Excluding Accrued Interest, Credit Loss Expense (Reversal) Seasoning based on monthly scheduled payments due from 1-12 payments Seasoning Based On Monthly Scheduled Payments Due From One To Twelve Payments In Percent Seasoning based on monthly scheduled payments due from one to twelve payments in percent. Type 1 of defined benefit contribution (up to) Type 1 of Defined Contribution Plan Type 1 of Defined Contribution Plan Earnings Per Share [Abstract] Earnings Per Share [Abstract] Interest recognized on derivatives Gain (Loss) on Fair Value Hedges Recognized in Earnings Short-Term Debt, Type [Axis] Short-Term Debt, Type [Axis] 2044 Maturity 2044 [Member] Maturity 2044 [Member] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Common stock repurchased under repurchase programs (in shares) Treasury Stock, Shares, Acquired Financing Receivable, Allowance for Credit Loss [Line Items] Financing Receivable, Allowance for Credit Loss [Line Items] Exercised (in dollars per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Current period recoveries, Year 3 Financing Receivable, Allowance for Credit Loss, Recovery, Originated Two Years Before Current Fiscal Year Financing Receivable, Allowance for Credit Loss, Recovery, Originated Two Years Before Current Fiscal Year Award Timing Disclosures [Line Items] Private Education Loans allowance for losses, Year 2 Financing Receivable, Allowance For Credit Loss, Originated Fiscal Year Before Latest Fiscal Year Financing Receivable, Allowance For Credit Loss, Originated Fiscal Year Before Latest Fiscal Year Total Private Education Loans in forbearance, Year 2 Financing Receivable, Loans In Forbearance, Year Two, Originated, Fiscal Year before Current Fiscal Year Financing Receivable, Loans In Forbearance, Year Two, Originated, Fiscal Year before Current Fiscal Year Measurement Frequency [Domain] Measurement Frequency [Domain] Delinquent Private Education Loans in repayment as a percentage of Private Education Loans in repayment, Year 1 Delinquencies As Percentage Of Loans In Repayment, Originated In Current Fiscal Year Delinquencies As Percentage Of Loans In Repayment, Originated In Current Fiscal Year Stockholders' Equity Equity [Text Block] Average purchase price per share (in dollars per share) Treasury Stock Acquired, Average Cost Per Share, Including Commission Costs Treasury Stock Acquired, Average Cost Per Share, Including Commission Costs U.S. State Deferred State and Local Income Tax Expense (Benefit) Loan Restructuring Modification [Domain] Loan Restructuring Modification [Domain] Loans held for investment (net of allowance for losses of $1,430,318 and $1,435,920, respectively) Loans held for investment, net Private Education Loans, net Financing Receivable, Excluding Accrued Interest, after Allowance for Credit Loss 2024-C ABS Transaction SMB Private Education Loan Trust 2024-C [Member] SMB Private Education Loan Trust 2024-C Net income Net income Net Income (Loss) Attributable to Parent Subsequent Event [Table] Subsequent Event [Table] Student loan premiums and discounts, net Deferred Tax Liabilities, Student Loan Premiums and Discounts, Net Deferred Tax Liabilities, Student Loan Premiums and Discounts, Net Total Capital (to Risk-Weighted Assets) Banking Regulation, Total Risk-Based Capital Ratio, Actual Private Education Loans deferred origination costs and unamortized premium/(discount), Year 4 Net Unamortized Premium Or Discount, Originated Three Years Before Current Fiscal Year Net Unamortized Premium Or Discount, Originated Three Years Before Current Fiscal Year Reconciliations of Statutory U.S. Federal Income Tax Rates to our Effective Tax Rate Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Vesting period Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period Loans In-School/Grace/Deferment Loans In-School/Grace/Deferment [Member] Loans In-School/Grace/Deferment Other, net Effective Income Tax Rate Reconciliation, Other Adjustments, Percent 2043 Maturity 2043 [Member] Maturity 2043 [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Income taxes payable, net Taxes Payable Common stock repurchased Payments for Repurchase of Common Stock Adoption Date Trading Arrangement Adoption Date Total Private Education Loans in forbearance, Year 5 Financing Receivable, Loans In Forbearance, Year Five, Originated, Four Years before Current Fiscal Year Financing Receivable, Loans In Forbearance, Year Five, Originated, Four Years before Current Fiscal Year 2024-B ABS transaction SMB Private Education Loan Trust 2024-B [Member] SMB Private Education Loan Trust 2024-B Customer relationships Customer Relationships [Member] Line of Credit Line of Credit [Member] Florida FLORIDA Schedule of Offsetting Liabilities Offsetting Liabilities [Table Text Block] Stock-Based Compensation Compensation Related Costs, Policy [Policy Text Block] Savings Interest-Bearing Domestic Deposit, Savings Ending total loans, gross Allowance Coverage Of Charge Offs Ending Loans Allowance coverage of charge-offs ending total loans. Retained earnings Retained earnings Retained Earnings (Accumulated Deficit) Schedule of Common Share Repurchases Class of Treasury Stock [Table Text Block] Sallie Mae 401(k) Savings Plan Sallie Mae 401(k) Savings Plan [Member] Sallie Mae 401(k) Savings Plan [Member] Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Class of Stock [Axis] Class of Stock [Axis] Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Impairment of intangible assets Impairment of Intangible Assets, Finite-Lived Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Other Deferred Tax Liabilities, Other Statement [Table] Statement [Table] Deferred tax provision (benefit) Total deferred provision (benefit) Deferred Income Tax Expense (Benefit) Adjustments to reconcile net income to net cash provided by (used in) operating activities: Adjustments to reconcile net income to net cash provided by operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] Reductions related to the lapse of statute of limitations Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations Financing activities Cash flows from financing activities: Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Nondeductible items Effective Income Tax Rate Reconciliation, Nondeductible Expense, Percent Purchase price Business Combination, Recognized Asset Acquired to Liability Assumed, Excess (Less), and Goodwill Loans Transferred to the Trust Debt Instrument, Loans Transferred Debt Instrument, Loans Transferred Expired capital losses Effective Income Tax Rate Reconciliation, Tax Credit, Expired Capital Losses, Amount Effective Income Tax Rate Reconciliation, Tax Credit, Expired Capital Losses, Amount Common Equity Tier 1 Capital (to Risk-Weighted Assets) Common Equity Tier One Risk Based Capital Common Equity Tier One Risk Based Capital Variable Rate [Domain] Variable Rate [Domain] 2024-D ABS transaction SMB Private Education Loan Trust 2024-D [Member] SMB Private Education Loan Trust 2024-D Loans in forbearance as a percentage of loans in repayment and forbearance, Year 1 Loans In Forbearance As Percentage Of Loans In Repayment And Forbearance Loans in forbearance as a percentage of loans in repayment and forbearance. Organization and Business Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Increments in which forbearance is granted Financing Receivable, Increments In Which Forbearance Is Granted Financing Receivable, Increments In Which Forbearance Is Granted Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Unsecured Borrowings - repaid Repayments of Unsecured Debt All Adjustments to Compensation All Adjustments to Compensation [Member] Interest Rate Reduction Contractual Interest Rate Reduction [Member] Amendment Flag Amendment Flag Shares authorized to be issued under plan (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized Condensed Income Statements, Captions [Line Items] Condensed Income Statements, Captions [Line Items] Transfers and Servicing [Abstract] Transfers and Servicing [Abstract] Less: Common stock held in treasury at cost: 244.0 million and 230.2 million shares, respectively Less: Common stock held in treasury at cost: 244.0 million and 230.2 million shares, respectively Treasury Stock, Common, Value Termination Date Trading Arrangement Termination Date Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] After two years to three years Time Deposit Maturities, Year Three Allowance for loan losses Allowance for loan losses Allowance for loan losses, beginning balance Allowance for loan losses, ending balance Private Education Loans allowance for losses Allowance for credit losses on loans and leases Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest Schedule of Stock Option Activity Share-Based Payment Arrangement, Option, Activity [Table Text Block] 2042 Maturity 2042 [Member] Maturity 2042 [Member] Average common shares outstanding (in shares) Weighted average shares used to compute basic EPS (in shares) Weighted Average Number of Shares Outstanding, Basic Current period recoveries, Year 1 Financing Receivable, Allowance for Credit Loss, Recovery, Originated In Current Fiscal Year Financing Receivable, Allowance for Credit Loss, Recovery, Originated In Current Fiscal Year New Jersey NEW JERSEY Unrecognized tax benefits recognition impact on effective tax rate Unrecognized Tax Benefits that Would Impact Effective Tax Rate Loans held for investment, net, difference Loans Receivable, Fair Value Disclosure, Difference Between Carrying Value And Fair Value Loans Receivable, Fair Value Disclosure, Difference Weighted Average Life of Class A and Class B Notes (in years) Debt Instrument, Weighted Average Life Debt Instrument, Weighted Average Life Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Exercisable (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Number Subsequent Events [Abstract] Subsequent Events [Abstract] Segment Reporting [Abstract] Acquisition transaction costs, net Amortization of Acquisition Costs Debt Disclosure [Abstract] Debt Disclosure [Abstract] Current period gross charge-offs, Year 1 Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest, Writeoff, Originated In Current Fiscal Year Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest, Writeoff, Originated In Current Fiscal Year Interest on income tax expense net of related tax benefit Unrecognized Tax Benefits, Interest on Income Taxes Expense Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Consolidated Entities [Axis] Consolidated Entities [Axis] Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Private Education Loans, net, Year 6 Financing Receivable, after Allowance for Credit Loss, Originated Five Years Before Current Fiscal Year Financing Receivable, after Allowance for Credit Loss, Originated Five Years Before Current Fiscal Year Percentage of Private Education Loans in repayment, Year 6 Percentage Of Loans In Repayment, Originated Five Or More Years Before Latest Fiscal Year Percentage Of Loans In Repayment, Originated Five Or More Years Before Latest Fiscal Year Cash and Cash Equivalents Cash and Cash Equivalents Disclosure [Text Block] Issuance price Debt Instrument, Issuance Price, Percentage Debt Instrument, Issuance Price, Percentage Options granted in period (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross Use of Estimates and Assumptions Use of Estimates, Policy [Policy Text Block] Settlements Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements 2024-F ABS Transaction SMB Private Education Loan Trust 2024-F [Member] SMB Private Education Loan Trust 2024-F Preferred stock dividends paid Payments of Dividends Total Capital (to Risk-Weighted Assets) Banking Regulation, Total Capital, Actual Summary of Black-Scholes Model Assumptions for Calculating ESPP Fair Values Schedule of Share-Based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block] Percent of private loans indexed to LIBOR or SOFR Percent of Private Loans indexed to LIBOR Or SOFR Percent of Private Loans indexed to LIBOR Or SOFR Total accrued interest by origination vintage, Year 6 Financing Receivable, Accrued Interest, Origination Interest, Originated Five or More Years before Latest Fiscal Year Financing Receivable, Accrued Interest, Origination Interest, Originated Five or More Years before Latest Fiscal Year Subsequent Events Subsequent Events [Text Block] Insider Trading Arrangements [Line Items] Long-term borrowings, difference Long-Term Debt, Fair Value, Difference Between Carrying Value And Fair Value Long-Term Debt, Fair Value, Difference Between Carrying Value And Fair Value After Year 5 Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year Canceled (in dollars per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price Loan delinquent, current Current Financial Asset, Not Past Due [Member] Private Education Loans allowance for losses, Year 4 Financing Receivable, Allowance For Credit Loss, Originated Three Years Before Current Fiscal Year Financing Receivable, Allowance For Credit Loss, Originated Three Years Before Current Fiscal Year Total liabilities Liabilities Percentage of discount available to employees under ESPP Share-Based Compensation Arrangement by Share-Based Payment Award, Discount from Market Price, Offering Date Financing receivable, excluding accrued interest, modified in period, to total financing receivables, percentage Financing Receivable, Excluding Accrued Interest, Modified in Period, to Total Financing Receivables, Percentage Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Increases resulting from tax positions taken during the current period Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Unfunded loan commitments for loans held for investment(6) Beginning balance Ending balance Fair Value Disclosure, off-Balance-Sheet Risks, Amount, Liability Proceeds from sales and maturities of available-for-sale securities Proceeds from Sale and Maturity of Debt Securities, Available-for-Sale Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Current period gross charge-offs, Year 6 Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest, Writeoff, Originated Five Or More Years Before Latest Fiscal Year Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest, Writeoff, Originated Five Or More Years Before Latest Fiscal Year 2024-E ABS Transaction SMB Private Education Loan Trust 2024-E [Member] SMB Private Education Loan Trust 2024-E Secured Borrowing Facility Fixed-rate borrowings ABCP Borrowings [Member] ABCP Borrowings [Member] Trade names and trademarks Trademarks and Trade Names [Member] Expense (reversal) financial receivable and off-balance sheet Financing Receivable And Off-Balance Sheet, Credit Loss, Expense (Reversal) Financing Receivable And Off-Balance Sheet, Credit Loss, Expense (Reversal) Private Education Loans deferred origination costs and unamortized premium/(discount), Year 3 Net Unamortized Premium Or Discount, Originated Two Years Before Current Fiscal Year Net Unamortized Premium Or Discount, Originated Two Years Before Current Fiscal Year Variable Rate [Axis] Variable Rate [Axis] Amount of variation margin included as settlement Amount Of Variation Margin Included As Settlement Amount Of Variation Margin Included As Settlement Available-for-sale investments Estimated Fair Value Debt Securities, Available-for-Sale Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Non-NEOs Non-NEOs [Member] Investment Program, Proportional Amortization Method, Applied, Amortization Expense, Statement of Cash Flows [Extensible Enumeration] Investment Program, Proportional Amortization Method, Applied, Amortization Expense, Statement of Cash Flows [Extensible Enumeration] Additional Loans the Bank Transferred to the Trust Additional Proceeds from Sale of Debt Securities, Available-for-sale Additional Proceeds from Sale of Debt Securities, Available-for-sale