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Total assets, gross amounts of recognized assets/liabilities Derivative Asset, Security Purchased under Agreement to Resell, and Security Borrowed, Subject to Master Netting Arrangement, before Offset 2030 Debt Instrument, Redemption, Period Five [Member] Series D Preferred Stock, Prior To August 15, 2031 Series D Preferred Stock, Prior To August 15, 2031 [Member] Series D Preferred Stock, Prior To August 15, 2031 Schedule of Location and Amounts of Gains and Losses Related to Interest and Amortization on Derivative Instruments Schedule of Derivative Instruments [Table Text Block] Short-term Debt, Type [Domain] Short-Term Debt, Type [Domain] Gain (loss) on cash flow hedges to be recognized within twelve months Cash Flow Hedge Gain (Loss) to be Reclassified within 12 Months Entity Address, City or Town Entity Address, City or Town Total sales and transfers Financing Receivable, Sale and Reclassification to Held-for-Sale FHLB stock Federal Home Loan Bank Stock Class of Financing 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Transferred Financial Assets, Other Remaining performance obligation, expected timing of satisfaction, period Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Cash paid for amounts included in the measurement of lease liabilities Cash Paid For Amounts Included In The Measurement Of Lease Liabilities Cash Paid For Amounts Included In The Measurement Of Lease Liabilities Originations and repayments of finance receivables and loans initially held-for-investment and other, net Originations And Repayments Of Loans Held-For-Investment And Other Originations And Repayments Of Loans Held-For-Investment And Other Total deposit liabilities Deposit liabilities Deposits 2027 Lessee, Operating Lease, Liability, to be Paid, Year One Depreciation and amortization Depreciation, Amortization and Accretion, Net Schedule of Long-term Debt Schedule of Long-Term Debt Instruments [Table Text Block] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, 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Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Other Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Other FHLB/FRB stock Federal Home Loan Bank Stock and Federal Reserve Bank Stock Federal Home Loan Bank Advances Federal Home Loan Bank Advances [Member] Vehicles Property, Plant, and Equipment, Lessor Asset under Operating Lease, before Accumulated Depreciation Deferred income taxes Increase (Decrease) in Deferred Income Taxes Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Transfers into Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 Credit Rating [Axis] Credit Rating, Fitch [Axis] Entity Address, State or Province Entity Address, State or Province Schedule of Available-for-Sale Securities in Unrealized Loss Position Schedule Of Available-For-Sale Securities In Unrealized Loss Position [Table Text Block] Schedule Of Available-For-Sale Securities In Unrealized Loss Position Purchases of equity securities Payments to Acquire Equity Securities, FV-NI Series C Preferred Stock Series C Preferred Stock [Member] PEO Total Compensation Amount PEO Total Compensation Amount Proportional amortization investments Investment, Proportional Amortization Method, Elected, Amount Assets Assets, Fair Value Disclosure [Abstract] Notional amount Derivative, Notional Amount Basic weighted-average common shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic Asset Pledged as Collateral with Right Asset Pledged as Collateral with Right [Member] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Due after five years through ten years Debt Securities, Held-to-Maturity, Maturity, Rolling after 5 through 10 Years, Weighted Average Yield AA Fitch, AA Rating [Member] 2030 Lessee, Operating Lease, Liability, to be Paid, Year Four Financing Receivable, Credit Quality Indicator [Line Items] Financing Receivable, Credit Quality Indicator [Line Items] Interest-bearing Interest-Bearing Deposits in Banks and Other Financial Institutions Discontinued hedge Discontinued Hedge [Member] Discontinued Hedge [Member] Remarketing losses, net Remarketing Gains (Losses), Net Remarketing Gains (Losses), Net Due after five years through ten years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 Financing receivable, nonaccrual, interest income Financing Receivable, Nonaccrual, Interest Income Total other revenue Other revenue Noninterest Income Amortized cost basis of available-for-sale securities Debt Securities, Available-for-Sale, Amortized Cost, Fiscal Year Maturity [Abstract] Net depreciation expense on operating lease assets Net depreciation expense on operating lease assets Depreciation, Lessor Asset under Operating Lease Finance Receivables and Loans, Net Loans, Notes, Trade and Other Receivables Disclosure [Text Block] 2031 and thereafter Long-Term ​Debt​, Maturity, After​ Year ​Four Long-Term ​Debt​, Maturity, After​ Year ​Four Certificates of deposit Time Deposits Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Preferred stock dividends paid Payments of Ordinary Dividends, Preferred Stock and Preference Stock Class of Stock [Axis] Class of Stock [Axis] Net income attributable to common shareholders Net Income (Loss) Available to Common Stockholders, Basic Other accounts receivable Accounts and Other Receivables, Net, Current Debt Securities, Held-to-maturity [Table] Debt Securities, Held-to-Maturity [Table] Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract] Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract] Accumulated amortization Intangible Asset, Finite-Lived, Accumulated Amortization Long-term debt, due within one year Long-Term Debt, Current Maturities Due in one year or less Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling within One Year 2031 and thereafter Sales-Type And Direct Financing Leases, Payment To Be Received, After Year Four Sales-Type And Direct Financing Leases, Payment To Be Received, After Year Four Total finance receivables and loans, net Finance receivables and loans, net Financing Receivable, Excluding Accrued Interest, after Allowance for Credit Loss Treasury stock, at cost (218,859,455 and 211,862,875 shares) Treasury Stock, Value Recently Issued Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] 2027 Sales-Type and Direct Financing Leases, Payment to be Received, Year One Unsecured Unsecured Debt [Member] Remarketing fees Remarketing Fees Remarketing fees. Schedule of Accrued Expenses and Other Liabilities Schedule of Accrued Liabilities [Table Text Block] Long-term debt Non-recourse debt Total long-term debt Long-Term Debt Accumulated depreciation Property, Plant, and Equipment, Lessor Asset under Operating Lease, Accumulated Depreciation Year three, originated, two years before current fiscal year Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year Net change in Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Net cash (used in) provided by investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Derivative assets, gross amounts not offset on the Condensed Consolidated Balance Sheet, collateral Derivative Asset, Subject to Master Netting Arrangement, Collateral, Obligation to Return Cash Not Offset Total liabilities, net amounts of assets/liabilities presented on the Condensed Consolidated Balance Sheet Derivative Liability, Security Sold under Agreement to Repurchase, and Security Loaned, Subject to Master Netting Arrangement, after Offset Security Exchange Name Security Exchange Name Series B Preferred Stock, On And After May 15, 2026 Series B Preferred Stock, On And After May 15, 2026 [Member] Series B Preferred Stock, On And After May 15, 2026 Hedged asset, last-of-layer, amount Hedged Asset, Fair Value Hedge, Portfolio Layer Method, Hedged Layer, Amount 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] Total liabilities Liabilities, Fair Value Disclosure Amortized cost of loans redefaulted Financing Receivable, Excluding Accrued Interest, Modified, Subsequent Default Fair value Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer Name Outstanding Recovery, Individual Name Award Timing, How MNPI Considered Award Timing, How MNPI Considered [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] Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Total undiscounted cash flows Sales-Type and Direct Financing Leases, Payment to be Received Investment in any one industry did not exceed percentage Equity Investment In Any One Industry Did Not Exceed Percentage Equity Investment In Any One Industry Did Not Exceed Percentage Maturity 61 to 90 Days Maturity 61 to 90 Days [Member] Maturity 61 to 90 Days Direct financing lease, interest income Direct Financing Lease, Interest Income Ally Financial Inc Ally Financial Inc [Member] Ally Financial Inc. Reclassification from AOCI, net of tax Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent Schedule of Investments [Table] Schedule of Investments [Table] Interest on long-term debt Interest Expense, Long-Term Debt Total purchases of finance receivables and loans Financing Receivable, Purchase Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Table] Noncash items Noncash Investing and Financing Items [Abstract] Direct financing lease, net investment in lease Direct Financing Lease, Net Investment in Lease, Excluding Accrued Interest, before Allowance for Credit Loss Schedule of Activity in Proportional Amortization Investment Investment Program, Proportional Amortization Method [Table Text Block] Investment Program, Proportional Amortization Method Investment securities Debt Securities [Member] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, by Asset Class [Domain] Asset Class [Domain] Compensation Amount Outstanding Recovery Compensation Amount Capitalized contract cost, amortization Capitalized Contract Cost, Amortization Individual: Individual [Axis] Diluted weighted-average common shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Diluted Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Entity Emerging Growth Company Entity Emerging Growth Company Series C Preferred Stock, On And After May 15, 2028 Series C Preferred Stock, On And After May 15, 2028 [Member] Series C Preferred Stock, On And After May 15, 2028 Finance receivables and loans, net of unearned income Finance receivables and loans, net Total finance receivables and loans Total finance receivables and loans Financing Receivable, 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Schedule of Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Securitizations and Variable Interest Entities Variable Interest Entity Disclosure [Text Block] Liabilities Liabilities [Abstract] Restricted cash held for securitization trusts Restricted Cash Collections For Securitization Trust Restricted cash collections for securitization trust. 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Commercial Commercial Portfolio Segment [Member] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Unfunded commitments for proportional amortization investments Unfunded commitments for proportional amortization investments Investment Program, Proportional Amortization Method, Elected, Commitment Current year Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Current Year Business Combination [Domain] Business Combination [Domain] Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Operating leases Operating lease revenue Operating Lease, Lease Income Financial Asset, Period Past Due [Domain] Financial Asset, Aging [Domain] Cash flows received on retained interests in securitization entities Cash Flows Between Transferor and Transferee, Beneficial Interest Schedule of Net Investment Hedges in Accumulated Other Comprehensive Income (Loss) Schedule of Net Investment Hedges in Accumulated Other Comprehensive Income (Loss) [Table Text Block] All Adjustments to Compensation All Adjustments to Compensation [Member] Common equity tier one capital, well capitalized minimum Banking Regulation, Common Equity Tier 1 Risk-Based Capital Ratio, Well Capitalized, Minimum Business Combination [Axis] Business Combination [Axis] Aggregate liquidation preference Preferred Stock, Liquidation Preference, Value Income Taxes Income Tax, Policy [Policy Text Block] Net cash provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Ally Credit Card Ally Credit Card [Member] Ally Credit Card Prior years Prior Year Claims and Claims Adjustment Expense Substandard Substandard [Member] Pledging Purpose [Domain] Pledging Purpose [Domain] Interest on cash and cash equivalents Interest Income, Deposits with Financial Institutions Income Statement [Abstract] Income Statement [Abstract] Document Transition Report Document Transition 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Status [Domain] Recourse Status [Domain] Accumulated other comprehensive losses excluded from Common Equity Tier 1 capital Banking Regulation, Accumulated Other Comprehensive Losses Excluded From Common Equity Tier 1 Risk-Based Capital Banking Regulation, Accumulated Other Comprehensive Losses Excluded From Common Equity Tier 1 Risk-Based Capital Investment program, proportional amortization method, elected, impairment loss Investment Program, Proportional Amortization Method, Elected, Impairment Loss Entity Entity [Domain] Number of shares issued (in shares) Preferred Stock, Shares Issued Total Debt Securities, Held-to-Maturity, Excluding Accrued Interest, After Allowance for Credit Loss, Yield Debt Securities, Held-to-Maturity, Excluding Accrued Interest, After Allowance for Credit Loss, Yield Financing Receivable, Credit Quality Indicator [Table] Financing Receivable, Credit Quality Indicator [Table] Other assets Increase (Decrease) in Other Operating Assets Number of shares issued (in shares) Stock Issued During Period, Shares, New Issues Net increase (decrease) in deposits Increase (Decrease) in Deposits Derivative assets, gross amounts offset on the Condensed Consolidated Balance Sheet Derivative Asset, Subject to Master Netting Arrangement, Liability Offset Measurement Basis [Axis] Measurement Basis [Axis] Proceeds from sales of finance receivables and loans initially held-for-investment Proceeds from Sale, Loan, Held-for-Investment Secured debt Secured Debt, Long-Term And Short-Term, Combined Amount Secured Debt, Long-Term And Short-Term, Combined Amount Tier one capital to risk-weighted assets, ratio Banking Regulation, Tier 1 Risk-Based Capital Ratio, Actual Cash equivalents Cash Equivalents, at Carrying Value Due in one year or less Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Unearned revenue, revenue recognized Contract with Customer, Liability, Revenue Recognized Subsequent Event Type [Domain] Subsequent Event Type [Domain] Agency mortgage-backed commercial Mortgage-Backed Securities, Issued By US Government Sponsored Enterprises, Commercial [Member] Mortgage-Backed Securities, Issued By US Government Sponsored Enterprises, Commercial Net realized/unrealized gains Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings [Abstract] Revolving loans Financing Receivable, Excluding Accrued Interest, Revolving, Writeoff Available-for-sale securities Available-for-sale securities AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member] Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Assets held-in-trust Asset, Held-in-Trust Deposited securities Deposit Assets Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Entity Current Reporting Status Entity Current Reporting Status Net cash provided by (used in) financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Total Shareholder Return Amount Total Shareholder Return Amount Total gain on fair value hedging relationships Total Interest And Amortization Income (Expense) Hedging Relationship Total amount of interest and amortization of basis adjustment income (expense) on hedging relationships. Liabilities Liabilities, Fair Value Disclosure [Abstract] Cash flow hedging Cash Flow Hedging [Member] Due after ten years Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years Investment in operating leases, net Investment in operating leases, net Property, Plant, and Equipment, Lessor Asset under Operating Lease, after Accumulated Depreciation Reconciliation of net income to net cash provided by operating activities Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] 2029 Long-Term Debt, Maturity, Year Three Corporate Finance operations Corporate Finance Operations Segment [Member] Corporate Finance Operations Segment Payment extensions, number of months extended/deferred Financing Receivable, Modified, Weighted-Average Term Increase from Modification Impairment of FHLB and FRB stock Federal Home Loan Bank Stock And Federal Reserve Bank Stock, Impairment Loss Federal Home Loan Bank Stock And Federal Reserve Bank Stock, Impairment Loss Net property and equipment Property, Plant, and Equipment, after Accumulated Depreciation, Depletion, and Amortization Financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] 2028 Debt Instrument, Redemption, Period Three [Member] Cash proceeds from transfers completed during the period Cash Flows Between Transferor and Transferee, Proceeds from New Transfers Financial Instruments [Domain] Financial Instruments [Domain] Schedule of Property Subject to or Available for Operating Lease Property, Plant, and Equipment, Lessor Asset under Operating Lease [Table Text Block] Year five, originated, four years before current fiscal year Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year Total assets, net amount Derivative Asset Other, net Other Income Deposit liabilities Deposit Contracts, Liabilities [Abstract] Offsetting [Abstract] Offsetting [Abstract] Underlying Securities Award Underlying Securities Amount Proceeds from sales and repayments of loans held-for-sale Proceeds from Sale and Collection, Loan, Held-for-Sale Estimated fair value Estimate of Fair Value Measurement [Member] Revenue from Contracts with Customers Revenue from Contract with Customer [Text Block] Net proceeds from issuance of Series D preferred stock Stock issued during period, value, new issues Stock Issued During Period, Value, New Issues Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Assets Assets, Total [Member] Combination Extended Maturity and Interest Rate Reduction [Member] Derivative Asset, Statement of Financial Position [Extensible Enumeration] Derivative Asset, Statement of Financial Position [Extensible Enumeration] Schedule of Quantitative Information and Net Credit Losses about Securitized and Other Financial Assets Managed Together Schedule Of Quantitative Information And Net Credit Losses About Securitized And Other Financial Assets Managed Together [Table Text Block] Tabular disclosure for the total principal amount outstanding, and delinquencies at the end of the period of securitized or asset-backed financing arrangement assets and any other financial assets that are managed together. Number of operating subsegments Number Of Operating Subsegments Number Of Operating Subsegments Ally Invest Ally Invest [Member] Ally Invest [Member] Total assets, gross amounts not offset on the Condensed Consolidated Balance Sheet, collateral Derivative Asset, Security Purchased under Agreement to Resell, and Security Borrowed, Subject to Master Netting Arrangement, Collateral, Obligation to Return Cash Not Offset Preferred stock Preferred Stock [Member] Other, net Payment for (Proceeds from) Other Investing Activity Operating lease, weighted average discount rate Operating Lease, Weighted Average Discount Rate, Percent Property, Plant, and Equipment, Lessor Asset under Operating Lease [Table] Property, Plant, and Equipment, Lessor Asset under Operating Lease [Table] 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] Segment Reporting [Table] Segment Reporting [Table] Total Financing Receivable, Excluding Accrued Interest, Modified in Period, Amount Certificates of deposit, in excess of $250,000 federal insurance limits Time Deposits, at or Above FDIC Insurance Limit Schedule of Lease, Cost Lease, Cost [Table Text Block] All Trading Arrangements All Trading Arrangements [Member] Fair value at beginning of the period Fair value at ending of the period Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value Fair value Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months Other Performance Measure, Amount Other Performance Measure, Amount Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Pledged assets for Federal Reserve Bank Pledged assets for Federal Reserve Bank [Member] Assets restricted as collateral to the Federal Reserve Bank [Member] Cash paid for Interest Paid, Including Capitalized Interest, Operating and Investing Activities [Abstract] Current Fiscal Year End Date Current Fiscal Year End Date 2028 Sales-Type and Direct Financing Leases, Payment to be Received, Year Two Derivative liabilities with no offsetting arrangements Derivative Liability, Not Subject to Master Netting Arrangement Schedule of Held to Maturity Debt Securities by Credit Quality Debt Securities, Held-to-Maturity, Credit Quality Indicator [Table Text Block] Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Provision for credit losses Financing Receivable, Excluding Accrued Interest, Credit Loss Expense (Reversal) Maturity 31 to 60 Days Maturity 31 to 60 Days [Member] Maturity 31 to 60 Days Technology and communications Communications and Information Technology Nonmarketable equity investments Nonmarketable equity investments Nonmarketable Equity Investments Nonmarketable Equity Investments Stock repurchased during period, number of shares (in share) Stock Repurchased During Period, Shares Yield Debt Securities, Available-for-Sale, Rolling Maturity, Weighted Average Yield [Abstract] 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] Cash dividends declared per common share (in dollars per share) Common Stock, Dividends, Per Share, Declared Entity File Number Entity File Number Net change in short-term borrowings Proceeds from (Repayments of) Short-Term Debt Schedule of Investments Classified by Contractual Maturity Date Investments Classified by Contractual Maturity Date [Table Text Block] Fair Value, Liability, Recurring Basis, Still Held [Abstract] Fair Value, Liability, Recurring Basis, Still Held [Abstract] Fair Value, Liability, Recurring Basis, Still Held Schedule of Liability for Unpaid Claims and Claims Adjustment Expense and Rollforward of Our Reserves for Insurance Losses and Loss Adjustment Expenses Schedule of Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Measure: Measure [Axis] Schedule of Variable Interest Entities Schedule of Variable Interest Entities [Table Text Block] Treasury stock, common, shares (in shares) Treasury Stock, Common, Shares Due after ten years Debt Securities, Held-to-Maturity, Maturity, Rolling after 10 Years, Weighted Average Yield Total assets, gross amounts not offset on the Condensed Consolidated Balance Sheet, financial instruments Derivative Asset, Security Purchased under Agreement to Resell, and Security Borrowed, Subject to Master Netting Arrangement, Deduction of Financial Instrument Not Offset Other Other Cost and Expense, Operating Equity Components [Axis] Equity Components [Axis] Capitalized contract cost, net Capitalized Contract Cost, Net Income taxes Income Tax Paid, after Refund Received Total assets, net amounts of assets/liabilities presented on the Condensed Consolidated Balance Sheet Derivative Asset, Security Purchased under Agreement to Resell, and Security Borrowed, Subject to Master Netting Arrangement, after Offset Entity Interactive Data Current Entity Interactive Data Current Due after one year through five years Debt Securities, Held-to-Maturity, Maturity, Rolling after One Through Five Years, Weighted Average Yield Due after one year through five years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year One Through Five Securities sold under agreement to repurchase, gross amounts not offset on the Condensed Consolidated Balance Sheet, financial instruments Security Sold under Agreement to Repurchase, Subject to Master Netting Arrangement, Deduction of Financial Instrument Not Offset Amount Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Fair Value [Abstract] Entity Small Business Entity Small Business Hedged asset, discontinued fair value hedge, cumulative increase (decrease) Hedged Asset, Discontinued Fair Value Hedge, Cumulative Increase (Decrease) Schedule of Pledged Assets for the Payment of the Related Secured Borrowings and Repurchase Agreements Pledged assets for the payment of the related secured borrowings and repurchase agreements [Table Text Block] Pledged assets for the payment of the related secured borrowings and repurchase agreements [Table Text Block] Unearned insurance premiums and service revenue Unearned Premiums Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Debt instrument, unamortized discount Debt Instrument, Unamortized Discount Tier one leverage to adjusted quarterly average assets, well-capitalized minimum Banking Regulation, Tier 1 Leverage Capital Ratio, Well Capitalized, Minimum Settlements Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Derivative assets, net amounts of assets/liabilities presented on the Condensed Consolidated Balance Sheet Derivative Asset, Subject to Master Netting Arrangement, after Offset Document Type Document Type Insurance commissions Insurance Commissions Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Loss on extinguishment of debt Loss on extinguishment of debt Gain (Loss) on Extinguishment of Debt Debt securities, available-for-sale, allowance for credit loss, excluding accrued interest Credit reserves, available-for-sale Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest Tier one leverage to adjusted quarterly average assets, ratio Banking Regulation, Tier 1 Leverage Capital Ratio, Actual Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Proceeds from issuance of long-term debt Proceeds from Issuance of Long-Term Debt Local Phone Number Local Phone Number Federal Home Loan Bank of Pittsburgh Federal Home Loan Bank of Pittsburgh [Member] Net investment hedging Net Investment Hedging [Member] Other comprehensive income (loss), before tax Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent Downward adjustments (including impairment) Equity Securities Without Readily Determinable Fair Value, Downward Price Adjustment And Accumulated Impairment Loss, Cumulative Amount Equity Securities Without Readily Determinable Fair Value, Downward Price Adjustment And Accumulated Impairment Loss, Cumulative Amount Nonrecourse Nonrecourse [Member] Pledged Status [Domain] Pledged Status [Domain] Income from continuing operations before income tax expense Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Cash collateral placed Securities Sold under Agreements to Repurchase, Fair Value of Collateral Contingencies (refer to Note 23) Commitments and Contingencies Debt Instrument, Redemption, Period [Domain] Debt Instrument, Redemption, Period [Domain] Property and equipment at cost Property, Plant, and Equipment, before Accumulated Depreciation, Depletion, and Amortization Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Executive Category: Executive Category [Axis] Residual value of leased asset Operating Lease, Residual Value of Leased Asset 2030 Lessor, Operating Lease, Payment to be Received, Year Four Accounts Payable and Accrued Liabilities [Abstract] Accounts Payable and Accrued Liabilities [Abstract] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Asset excluded from amortized cost of hedged asset, portfolio layer method Hedged Asset, Fair Value Hedge, Portfolio Layer Method, Hedged Layer, Fair Value, Cumulative Increase (Decrease), Excluded from Amortized Cost Loss on mortgage and automotive loans, net Loss on mortgage and automotive loans, net Gain (Loss) on Sales of Loans, Net Schedule of Variable Interest Entities [Table] Variable Interest Entity [Table] Supplemental disclosures Supplemental Cash Flow Information [Abstract] Due after ten years Debt Securities, Available-for-Sale, Maturity, Rolling after 10 Years, Weighted Average Yield Entity Address, Address Description Entity Address, Address Description Securitizations And Variable Interest Entities [Abstract] Securitizations And Variable Interest Entities [Abstract] Securitizations and Variable Interest Entities [Abstract] PEO Name PEO Name Total net insurance losses and loss adjustment expenses paid or payable Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid Accrued expenses and other liabilities Total accrued expenses and other liabilities Accrued Liabilities and Other Liabilities Cash flow hedges Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Residual value guarantee, percentage Residual Value Guarantee Residual Value Guarantee Other Segment Reporting, Other Segment Item, Amount Property, Plant and Equipment, Type [Axis] Long-Lived Asset, Class [Axis] Interest-bearing deposits Interest-Bearing Deposit Liabilities, Domestic, by Component [Abstract] Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Entity Tax Identification Number Entity Tax Identification Number Derivative Instruments and Hedging Activities Disclosures [Table] Derivative Instruments and Hedging Activities Disclosures [Table] Noninterest-bearing Cash and Due from Banks Interest and dividends on investment securities and other earning assets Interest and dividends on investment securities Interest and Dividend Income, Securities, Operating Schedule of Past Due Financing Receivables Financing Receivable, Past Due [Table Text Block] Current Financial Asset, Not Past Due [Member] Preferred stock dividends Preferred Stock Dividends, Income Statement Impact Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Variable lease payments, excessive wear and tear Variable Lease Payments, Excessive Wear And Tear Variable lease payments related to excess mileage and wear and tear on operating lease vehicles. Debt instrument, reference asset amount Debt Instrument, Reference Asset Amount Debt Instrument, Reference Asset Amount Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Purchases and originations Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases Derivative liabilities, net amount Derivative Liability, Subject to Master Netting Arrangement, after Offset and Deduction Equity Equity Contract [Member] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Automotive Finance operations Automotive Finance Operations Segment [Member] Automotive finance operations [Member] 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] Measurement Frequency [Domain] Measurement Frequency [Domain] Debt Instrument [Axis] Debt Instrument [Axis] Interest expense Interest Expense, Operating and Nonoperating [Abstract] Compensation and benefits expense Labor and Related Expense Total lease expense, net Lease, Cost Disposal Group Name [Axis] Disposal Group Name [Axis] Proceeds from repayments of held-to-maturity securities Proceeds from Maturities, Prepayments and Calls of Held-to-Maturity Securities Schedule of Derivative Instruments in Statement of Financial Position Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Net income (in dollars per share) Earnings Per Share, Basic Insider Trading Arrangements [Line Items] Long-term debt, due after one year Long-Term Debt, Excluding Current Maturities Hedged liability, fair value hedge, cumulative increase (decrease) Hedged Liability, Fair Value Hedge, Cumulative Increase (Decrease) Total financing revenue and other interest income Total financing revenue and other interest income Total Financing Revenue And Other Interest Income Represents the total of interest income, dividend income, and income from operating leases. Noncancelable lease term Lessee, Operating Lease, Noncancellable Lease Term Lessee, Operating Lease, Noncancellable Lease Term Schedule of Short-term Debt Schedule of Short-Term Debt [Table Text Block] BBB Fitch, BBB Rating [Member] 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] Credit-linked note derivatives Credit-Linked Note Derivatives [Member] Credit-Linked Note Derivatives Fair Value Measurement [Domain] Fair Value Measurement [Domain] Recoveries Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Recovery Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Cover [Abstract] 12 months or longer Debt Securities, Available-for-Sale, Unrealized Loss Position, Long [Abstract] Debt Securities, Available-for-Sale, Unrealized Loss Position, Long Disposal Group, Held-for-Sale or Disposed of by Sale, Not Discontinued Operations Disposal Group, Held-for-Sale or Disposed of by Sale, Not Discontinued Operations [Member] Variable Interest Entity Variable Interest Entity [Member] Variable Interest Entity Upward adjustments Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Annual Amount Year two, originated, fiscal year before current fiscal year, writeoff Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year, Writeoff Reserves for Insurance Losses and Loss Adjustment Expenses Short-Duration Insurance and Deposit Contracts [Text Block] Schedule of Equity Securities without Readily Determinable Fair Value Equity Securities without Readily Determinable Fair Value [Table Text Block] Equity Awards Adjustments Equity Awards Adjustments [Member] Equity investments without a readily determinable fair value Equity Securities without Readily Determinable Fair Value, Annual Amount [Abstract] Due in one year or less Debt Securities, Available-for-Sale, Maturity, Rolling within One Year, Weighted Average Yield Hedging Relationship [Domain] Hedging Relationship [Domain] Net deferred tax assets Deferred Tax Assets, Net Investment Program, Proportional Amortization Method, Elected, Income Tax Credit and Other Income Tax Benefit, after Amortization, Statement of Cash Flows [Extensible Enumeration] Investment Program, Proportional Amortization Method, Elected, Income Tax Credit and Other Income Tax Benefit, after Amortization, Statement of Cash Flows [Extensible Enumeration] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Schedule of Lessor, Operating Lease, Payments to be Received, Maturity Lessor, Operating Lease, Payment to be Received, Maturity [Table Text Block] Preferred stock issuance Proceeds from Issuance of Preferred Stock and Preference Stock Other liabilities Increase (Decrease) in Other Operating Liabilities Revolving loans converted to term Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan, Writeoff Pass Pass [Member] Schedule of Accounts, Notes, Loans and Financing Receivable Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Series D Preferred Stock Series D Preferred Stock [Member] Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Assets sold to nonconsolidated VIEs Continuing Involvement with Transferred Financial Assets, Principal Amount Outstanding Hedged asset, fair value hedge, cumulative increase (decrease) Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease) Disposals of operating lease assets Disposals Of Operating Lease Assets The cash inflow from the disposal of operating lease assets. Schedule of Realized Gain (Loss) Schedule of Realized Gain (Loss) [Table Text Block] Number of shares authorized (in shares) Preferred Stock, Shares Authorized Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Hedging Designation [Domain] Hedging Designation [Domain] Class of Stock [Domain] Class of Stock [Domain] Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Sales Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales Forwards Foreign Exchange Forward [Member] Schedule of Preferred Stock Schedule of Stock by Class [Table Text Block] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Accounts payable Accounts Payable Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward] Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward] Income Taxes Income Tax Disclosure [Text Block] Write-downs from transfers to held-for-sale Financing Receivable, Excluding Accrued Interest, Transfer out, Allowance for Credit Loss, Expense Reversal Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Tax credits and other tax benefits from proportional amortization investments Investment Program, Proportional Amortization Method, Elected, Income Tax Credit and Other Income Tax Benefit, before Amortization Expense Entity Filer Category Entity Filer Category Schedule of Offsetting Liabilities Offsetting Liabilities [Table Text Block] Consumer automotive Automobile Loan [Member] Lease and loan administration Lease And Loan Administration Lease and loan administration. Fixed-rate automotive loans Fixed-rate Automotive Loans [Member] Fixed-rate Automotive Loans [Member] Gain (loss) recognized in earnings Gain (Loss) on Derivative Instruments, Net, Pretax Federal Home Loan Bank Federal Home Loan Bank, Advance, Maturity, Year One Financial Asset, Period Past Due [Axis] Financial Asset, Aging [Axis] Due after one year through five years Debt Securities, Available-for-Sale, Maturity, Rolling after One Through Five Years, Weighted Average Yield Total derivatives not designated as accounting hedges Not Designated as Hedging Instrument [Member] Deposits [Abstract] Deposits [Abstract] Investments, Debt and Equity Securities [Abstract] Investments, Debt and Equity Securities [Abstract] Included in earnings Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss) Loss on sales of financial assets Securitization or Asset-Backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale, Gain (Loss) on Sale Securities sold under agreements to repurchase, gross amounts offset on the Condensed Consolidated Balance Sheet - gross amounts offset on the consolidated balance sheet Security Sold under Agreement to Repurchase, Subject to Master Netting Arrangement, Asset Offset Entity Address, Address Line Two Entity Address, Address Line Two Preferred stock redemption Payments for Repurchase of Redeemable Preferred Stock Schedule of Stock by Class [Table] Stock, Class of Stock [Table] Insurance operations Insurance Operations Segment [Member] Insurance Operations [Member] Total derivative contracts in a payable position Derivative Liability Entity Address, Address Line One Entity Address, Address Line One Right-of-use asset obtained in exchange for operating lease liability Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Income tax expense from continuing operations Income tax (benefit) expense from continuing operations Income Tax Expense (Benefit) Total assets, net amount Derivative Asset, Security Purchased under Agreement to Resell, and Security Borrowed, Subject to Master Netting Arrangement, after Offset and Deduction Other Operating Expenses Other Operating Income and Expense [Text Block] Pledged Assets related to secured borrowings [Line Items] Financial Instruments Owned and Pledged as Collateral [Line Items] Charge-offs Total Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff On‑balance sheet variable interest entities Variable Interest Entity, Primary Beneficiary [Member] Principal forgiveness, amount forgiven Financing Receivable, Modified, Principal Forgiveness, Amount Financing Receivable, Modified, Principal Forgiveness, Amount AOCI Attributable to Parent, Net of Tax [Roll Forward] AOCI Attributable to Parent, Net of Tax [Roll Forward] Trial modifications, term Financing Receivable, Trial Modifications, Term Financing Receivable, Trial Modifications, Term Interest on loans held-for-sale Interest and Fee Income, Financing Receivable, Held-for-Sale Loan Restructuring Modification [Domain] Loan Restructuring Modification [Domain] Statement [Table] Statement [Table] Tier one capital to risk-weighted assets, well-capitalized minimum Banking Regulation, Tier 1 Risk-Based Capital Ratio, Well Capitalized, Minimum Year two, originated, fiscal year before current fiscal year Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year Schedule of Financing Receivables, Nonaccrual Status Financing Receivable, Nonaccrual [Table Text Block] Derivative Instruments and Hedging Activities Disclosures [Line Items] Derivative Instruments and Hedging Activities Disclosures [Line Items] Total liabilities, gross amounts not offset on the Condensed Consolidated Balance Sheet, financial instruments Derivative Liability, Security Sold under Agreement to Repurchase, and Security Loaned, Subject to Master Netting Arrangement, Deduction of Financial Instrument Not Offset Minimum capital conservation buffer Banking Regulation, Capital Conservation Buffer, Capital Conserved, Minimum Derivative assets, gross amounts of recognized assets/liabilities Derivative Asset, Subject to Master Netting Arrangement, before Offset Unfunded commitments, period to be paid Investment Program, Proportional Amortization Method, Elected, Commitment, Period To Be Paid Investment Program, Proportional Amortization Method, Elected, Commitment, Period To Be Paid Other Other Other Loans [Member] All loans not classified as automotive or mortgage loans. Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract]