Interchange litigation Interchange Litigation [Member] Interchange Litigation [Member] Supplemental information: Supplemental Cash Flow Information [Abstract] Securities available for sale AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member] Letter of credit Letter of Credit [Member] Consolidated Entities [Axis] Consolidated Entities [Axis] Preferred stock, shares outstanding Preferred Stock, Shares Outstanding Other intangible assets Other Intangible Assets [Member] Securitization of Loans Transfers and Servicing of Financial Assets, Transfers of Financial Assets, Policy [Policy Text Block] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Total derivative liabilities Derivative liability Derivative Liability Due > 1 Year through 5 Years Debt Securities, Available-for-sale, Maturity, Rolling after One Through Five Years, Weighted Average Yield Yield Measurement Input, Yield [Member] Measurement input using interest rate correlation Carrying Amount Of Liabilities Carrying Amount Of Liabilities The carry amount of liabilities in fair value hedging relationship Amortized cost of securities available for sale Available-for-sale Securities, Expected Debt Maturities, Amortized Cost Basis, Rolling Maturity Available-for-sale Securities, Expected Debt Maturities, Amortized Cost Basis, Rolling Maturity Commitments, Contingencies, Guarantees and Others Commitments Contingencies and Guarantees [Text Block] Other comprehensive income (loss), before tax Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent Other Non-interest income Noninterest Income, Other Derivatives Instruments and Hedging Activities Derivatives, Policy [Policy Text Block] Federal funds purchased and securities loaned or sold under agreements to repurchase Federal Funds Purchased and Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure FX spot transactions FX spot transactions [Domain] FX spot transactions Changes in cash, cash equivalents and restricted cash for securitization investors Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Fair value of RMBS, cumulative effects from the CECL adoption Fair Value, RMBS, Cumulative Effects from the Adoption of the CECL Standard Fair Value, RMBS, Cumulative Effects from the Adoption of the CECL Standard Securities available for sale Available-for-sale Securities, Expected Debt Maturities, Fair Value, Rolling Maturity [Abstract] Available-for-sale Securities, Expected Debt Maturities, Fair Value, Rolling Maturity [Abstract] Class of Financing Receivable [Axis] Class of Financing Receivable [Axis] Non-Recoverable Rate Non-Recoverable Rate [Member] Non-Recoverable Rate [Member] Settlements Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Settlements Reclassifications from AOCI Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] Investment securities Interest and dividend income, securities Interest and Dividend Income, Securities, Operating Fair value hedges Fair Value Hedging [Member] Mortgage Servicing Rights Transfers and Servicing of Financial Assets, Servicing of Financial Assets, Policy [Policy Text Block] Document Fiscal Year Focus Document Fiscal Year Focus Minimum exercise price range (in dollars per share) Share-based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit Amortization of intangibles Amortization of Intangible Assets Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Net Unrealized Gains (Losses) Included in OCI Related to Assets and Liabilities Still Held Fair Value, Assets Measure on Recurring Basis, Unrealized Gain (Loss) in OCI Amount of unrealized gain (loss) which is included in other comprehensive income related to those assets still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3) Derivative, collateral, obligation to return cash Derivative, Collateral, Obligation to Return Cash Anti-dilutive options excluded from the computation of diluted earnings per share (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Other non-interest income Other Non-Interest Income [Member] Other Non-Interest Income [Member] Accrued interest receivable Financing Receivable, Accrued Interest, before Allowance for Credit Loss Cash flow hedges Cash Flow Hedging [Member] Changes in interest payable Increase (Decrease) in Interest Payable, Net Total Gains or (Losses) (Realized/Unrealized), Included in Net Income Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings Greater than 90 days Financial Asset, Equal to or Greater than 90 Days Past Due [Member] Guarantee obligation Guarantor Obligations, Current Carrying Value Schedule of Available-for-Sale Securities Schedule of Available-for-sale Securities Reconciliation [Table Text Block] Nonrecurring Fair Value, Nonrecurring [Member] Marketing Marketing Expense Issuances Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances VIE, nonconsolidated, carrying amount of assets included in certain investment structures Variable Interest Entities, nonconsolidated, Carrying amount of Assets included in certain investment structures In certain investment structures, we consolidate a VIE which in turn holds as its primary asset an investment in an unconsolidated VIE. This concept represents the carrying amount of assets related to these investment structures. Schedule of Contractual Maturities for Securities Investments Classified by Contractual Maturity Date [Table Text Block] Term loans by vintage year five Financing Receivable, Excluding Accrued Interest, Year Five, Originated, Four Years before Current Fiscal Year Class of Financing Receivable [Domain] Class of Financing Receivable [Domain] Transfers and Servicing of Financial Assets Transfers and Servicing of Financial Assets [Text Block] Preferred stock (par value $0.01 per share; 50,000,000 shares authorized; 6,075,000 and 4,975,000 shares issued and outstanding as of September 30, 2021 and December 31, 2020, respectively) Preferred Stock, Value, Issued Currency [Axis] Currency [Axis] Unconsolidated Variable Interest Entity, Not Primary Beneficiary [Member] Retained Earnings Retained Earnings [Member] Total deposits Total deposits Total Deposits Deposits Interest expense: Interest Expense [Abstract] Financing Receivable, Past Due [Line Items] Financing Receivable, Past Due [Line Items] Schedule of Intangible Assets by Major Class [Table] Schedule of Intangible Assets by Major Class [Table] Schedule of Intangible Assets by Major Class [Table] Interest income for loans classified as nonperforming Financing Receivable, Nonaccrual, Interest Income Schedule of Letter of Credit and Other Loan Commitments Schedule of Letter of Credit and Other Loan Commitments [Table Text Block] Schedule of Letter of credit and other loan commitments Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Depositary Shares, Each Representing a 1/40th Interest in a Share of Fixed Rate Non-Cumulative Perpetual Preferred Stock, Series I Series I Preferred Stock Series I Preferred Stock [Member] Outstanding nonredeemable series I preferred stock or outstanding series I preferred stock. Classified within stockholders' equity if nonredeemable or redeemable solely at the option of the issuer. Classified within temporary equity if redemption is outside the control of the issuer. Interest expense - Securitized Debt Obligation Interest expense - Securitized Debt Obligation [Member] Interest expense - Securitized Debt Obligation [Member] Schedule of Available-for-Sale Securities in Gross Unrealized Loss Position Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value [Table Text Block] RMBS, Agency Residential Mortgage Backed Securities, Agency [Member] Securities collateralized by agency residential real estate mortgage loans. Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract] Dividends and undistributed earnings allocated to participating securities Participating Securities, Distributed and Undistributed Earnings (Loss), excluding Preferred Stock Dividends, Basic Participating Securities, Distributed and Undistributed Earnings (Loss), excluding Preferred Stock Dividends, Basic Net income (loss) per basic common share Net income (loss) per basic common share (in dollars per share) Earnings Per Share, Basic Due after 5 years through 10 years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Amortized Cost 30-59 days Financial Asset, 30 to 59 Days Past Due [Member] Document Type Document Type Canada Canada CANADA Other Other Noninterest Expense Realized losses (gains) on foreign exchange contracts reclassified from AOCI Realized Gains (Losses) on Foreign Exchange Contracts Reclassified from AOCI Realized Gains (Losses) on Foreign Exchange Contracts Reclassified from AOCI Commercial MSR, accumulated amortization Servicing Asset at Amortized Cost, Accumulated Amortization Servicing Asset at Amortized Cost, Accumulated Amortization Fair Value Measurement [Domain] Fair Value Measurement [Domain] Diluted earnings per common share: Earnings Per Share, Diluted [Abstract] Entity Current Reporting Status Entity Current Reporting Status TDR Disclosures Financing Receivable, Troubled Debt Restructuring [Table Text Block] Cumulative effects from adoption of new accounting standards Cumulative Effect, Period of Adoption, Adjustment [Member] Noncriticized Pass [Member] Other (including (gains) and losses from equity investments) Other Noncash Income (Expense) Accrued interest receivable Debt Securities, Available-for-sale, Change in Present Value, Interest Income Securitized debt obligations Secured Debt Restricted cash for securitization investors Restricted Cash and Cash Equivalents Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent Net unrealized gains (losses) on hedging relationships Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax Deferred compensation plan assets Deferred Compensation Plan Assets Commercial And Industrial [Member] Commercial And Industrial [Member] Commercial and industrial. Redemptions Payments For Redemption Of Preferred Stock Payments For Redemption Of Preferred Stock Consumer Banking Consumer Portfolio Segment [Member] Issuance of securitized debt obligations Proceeds from Issuance of Secured Debt Assets: Assets, Fair Value Disclosure [Abstract] Carrying value Long-term Debt Derivative liability, netting adjustments Derivative liability, netting adjustments Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset Level 1 Fair Value, Inputs, Level 1 [Member] Investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Other liabilities Other Liabilities Loan Portfolio Composition and Aging Analysis Financing Receivable, Past Due [Table Text Block] Other contingently issuable shares Incremental Common Shares Attributable to Dilutive Effect of Contingently Issuable Shares Credit card loan securitizations Credit Card Credit Card Receivable [Member] Allowance for Credit Losses on Financing Receivables Financing Receivable, Allowance for Credit Loss [Table Text Block] Voting Interest Entities Consolidation, Subsidiaries or Other Investments, Consolidated Entities, Policy [Policy Text Block] Pending litigation Pending Litigation [Member] Additional paid-in capital, net Additional Paid in Capital Other Other Other Comprehensive Income Other, Net Of Tax, Attributable To Parent Other Comprehensive Income Other, Net Of Tax, Attributable To Parent Proceeds from sales and paydowns Proceeds from Sale and Collection of Loans Held-for-sale Hedging Relationship [Domain] Hedging Relationship [Domain] Exercises of stock options Stock Issued During Period, Value, Stock Options And Warrants Exercised And Restricted Stock Vesting Stock Issued During Period, Value, Stock Options And Warrants Exercised And Restricted Stock Vesting Financing Receivable Allowance for credit loss Translation Adjustments and Purchase Credit Deteriorated Loans Financing Receivable Allowance For Credit Loss Translation Adjustments And Purchase Credit Deteriorated Loans Financing Receivable Allowance For Credit Loss Translation Adjustments And Purchase Credit Deteriorated Loans Debt Securities, Available-for-sale, Realized Gain Debt Securities, Available-for-sale, Realized Gain Other Other Contract Revenue [Member] Other contract revenue [Member] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Schedule of Preferred Stock Schedule of Stock by Class [Table Text Block] Gross Unrealized Gains Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Redemptions of preferred stock Stock Redeemed or Called During Period, Value Other borrowings Other Borrowings Trading Symbol Trading Symbol Gross amounts Securities Sold under Agreements to Repurchase, Gross Net charge-offs Financing Receivable, Allowance for Credit Loss, Writeoff, after Recovery Loans held for sale: Increase (Decrease) in Loans Held-for-sale [Abstract] Total weighted average yield Debt Securities, Available-for-Sale, Weighted Average Yield Criticized nonperforming Nonperforming Financial Instruments [Member] Loans Loans, Notes, Trade and Other Receivables, Excluding Allowance for Credit Losses [Text Block] Accounting Policies [Abstract] Accounting Policies [Abstract] Derivative Instrument [Axis] Derivative Instrument [Axis] Cash balance of spread or reserve accounts, non-mortgage Continuing Involvement with Continued to be Recognized Transferred Financial Assets, Cash Balance in Spread and Reserve Accounts Continuing Involvement with Continued to be Recognized Transferred Financial Assets, Cash Balance in Spread and Reserve Accounts Common stock (par value $0.01 per share; 1,000,000,000 shares authorized; 684,515,909 and 679,932,837 shares issued as of September 30, 2021 and December 31, 2020, respectively; 430,375,948 and 458,972,202 shares outstanding as of September 30, 2021 and December 31, 2020, respectively) Common Stock, Value, Issued Income from continuing operations, net of tax Income from continuing operations, net of tax Income (loss) from continuing operations, net of tax Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent Schedule of Fair Value of Financial Instruments Fair Value, by Balance Sheet Grouping [Table Text Block] CMBS Commercial Mortgage Backed Securities [Member] Commercial and multifamily real estate Commercial And Multifamily Real Estate [Member] Property that is used for business purposes or multifamily residential. Beginning balance Ending balance Net derivative assets (liabilities) Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Investment Securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Stock options Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Goodwill [Line Items] Goodwill [Line Items] Investment Securities Marketable Securities, Policy [Policy Text Block] Class of Stock [Axis] Class of Stock [Axis] Total other debt Debt, Excluding Secured Debt Debt, Excluding Secured Debt Average Term Extension (Months) Financing Receivable, Modifications, Average Term Extension Financing Receivable, Modifications, Average Term Extension Collaborative Arrangement and Arrangement Other than Collaborative [Axis] Collaborative Arrangement and Arrangement Other than Collaborative [Axis] Net interest income Interest income Net interest income (loss) Interest Income (Expense), Net Allowance for Credit Losses [Roll Forward] Financing Receivable, Allowance for Credit Loss [Roll Forward] Financing Receivable, Allowance for Credit Loss [Roll Forward] 0.800% Senior Notes Due 2024 Senior Notes Due 2024 [Member] 0.800% Senior Notes Due 2024 Total Loans Modified Financing Receivable, Troubled Debt Restructuring, Postmodification Total Gains or (Losses) (Realized/Unrealized), Included in Net Income Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings Schedule of Level 3 Inputs Reconciliation Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax, Portion Attributable to Parent Dividend per share on common stock declared (in dollars per share) Common Stock, Dividends, Per Share, Declared Total contract revenue Revenue from Contract with Customer, Excluding Assessed Tax Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Amortized Cost Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Amortized Cost Other Interest and dividend income, other Other Interest and Dividend Income Stock option Share-based Payment Arrangement, Option [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Equity [Abstract] Equity [Abstract] Consolidation Items [Domain] Consolidation Items [Domain] Auto loan securitizations Auto Collateralized Auto Loans [Member] Derivative liabilities, offsetting cash collateral Derivative Liability, Collateral, Right to Reclaim Cash, Offset Financing Receivable, Troubled Debt Restructuring [Table] Financing Receivable, Troubled Debt Restructuring [Table] Measurement Input Type [Domain] Measurement Input Type [Domain] Fair Value - Less than 12 Months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months Business Segments and Revenue from Contracts with Customers Segment Reporting Disclosure [Text Block] TDRs Financing Receivable, Troubled Debt Restructuring Loans Financing Receivable [Policy Text Block] Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Appraisal value Appraisal Value [Member] Appraisal value. Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Voluntary prepayment rate Measurement Input, Constant Prepayment Rate [Member] Transfers Out of Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 Additional Paid-In Capital Additional Paid-in Capital [Member] % of TDR Activity Financing Receivable, Modifications, Percentage of Troubled Debt Restructuring Activity Financing Receivable, Modifications, Percentage of Troubled Debt Restructuring Activity Unamortized premiums and discounts, deferred fees and costs Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Cash and cash equivalents: Cash and Cash Equivalents [Abstract] International card businesses: Geographic Distribution, Foreign [Member] Interest payable Interest Payable Derivative asset, netting adjustments Derivative asset, netting adjustments Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset Net loans held for investment Financing Receivable, after Allowance for Credit Loss Net securities gains Net securities losses (gains) Debt and Equity Securities, Gain (Loss) Changes in other liabilities Increase (Decrease) in Other Operating Liabilities Net cash from other investing activities Payments for (Proceeds from) Other Investing Activities Sales Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Sales Maximum Maximum Maximum [Member] Entities that provide capital to low-income and rural communities Investment Companies Providing Capital to Low-Income and Rural Communities [Member] Investment Companies Providing Capital to Low-Income and Rural Communities Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Axis] Customer net revenue range Customer Net Revenue Range Customer Net Revenue Range Deposits and Borrowings Debt and Deposit Liabilities Disclosures [Text Block] Information about short-term and long-term debt arrangements, including amounts of borrowings, repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements. Also includes the entire disclosure for deposit liabilities including data and tables. Depositary Shares, Each Representing a 1/40th Interest in a Share of Fixed Rate Non-Cumulative Perpetual Preferred Stock, Series H Series H Preferred Stock Series H Preferred Stock [Member] Other debt: Other Debt [Abstract] Other debt. Financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Total stockholders’ equity Beginning balance Ending balance Stockholders' Equity Attributable to Parent Swap rates Measurement Input, Swap Rates [Member] Measurement input using swap rates Financing Receivable, Allowance for Credit Loss [Table] Financing Receivable, Allowance for Credit Loss [Table] Derivatives designated as accounting hedges Designated as Hedging Instrument [Member] Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Net Unrealized Gains (Losses) Included in Net Income Related to Assets and Liabilities Still Held Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss) Purchases of treasury stock Payments for Repurchase of Common Stock Stockholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] Due after 1 year through 5 years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value Customer accommodation Customer Accommodation [Member] Customer accommodation derivative contracts Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items] Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items] Preferred stock: Preferred Stock, Financing Activities [Abstract] Preferred Stock, Financing Activities [Abstract] Operating segments Operating Segments [Member] Award Share-based Payment Arrangement [Member] Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Principal Forgiveness Principal Forgiveness [Member] Discounted cash flows Valuation Technique, Discounted Cash Flow [Member] Due > 10 Years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Amortized Cost Income Statement [Abstract] Income Statement [Abstract] Loan Restructuring Modification [Axis] Loan Restructuring Modification [Axis] Nonperforming Loans Financing Receivable, Nonaccrual Fair Value Inputs Level 1 And Level 2 [Member] Fair Value Inputs Level 1 And Level 2 [Member] Fair Value Inputs Level 1 And Level 2 Federal Home Loan banks Federal Home Loan banks [Member] Federal Home Loan banks [Member] Litigation cof_LossContingencyRelatedtoLitigationMattersPolicyTextBlock [Policy Text Block] cof_LossContingencyRelatedtoLitigationMattersPolicyTextBlock Income tax provision (benefit) Income tax provision Income Tax Expense (Benefit) Other adjustments(1) Goodwill, Other Increase (Decrease) Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Net exposure Securities Sold under Agreements to Repurchase, Amount Offset Against Collateral Investment Type [Axis] Investment Type [Axis] Entity Voluntary Filers Entity Voluntary Filers Loans: Financing Receivable, before Allowance for Credit Loss [Abstract] Affordable housing tax credits Affordable Housing Tax Credits and Other Tax Benefits, Amount Reclassification adjustment from AOCI on derivatives, net of tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax Changes in interest receivable Increase (Decrease) in Accrued Interest Receivable, Net Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Other assets Other Assets, Fair Value Disclosure Stock-based Compensation Share-based Payment Arrangement [Policy Text Block] Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Restricted Equity Investments cof_ Restricted Equity Investments Policy Text Block [Policy Text Block] cof_ Restricted Equity Investments Policy Text Block Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Entity Small Business Entity Small Business Hedged Items In Fair Value Hedging Relationship [Table] Hedged Items In Fair Value Hedging Relationship [Table] Table shows the carrying amount and associated cumulative basis adjustment related to the application of hedge accounting that is included in the carrying amount of hedged assets and liabilities in fair value hedging relationships. Equity Component [Domain] Equity Component [Domain] Financing Receivable, Allowance for Credit Loss [Line Items] Financing Receivable, Allowance for Credit Loss [Line Items] Intangible assets gross including Goodwill Intangible Assets Gross Including Goodwill Intangible Assets Gross Including Goodwill Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Securities Resale and Repurchase Agreements Repurchase and Resale Agreements Policy [Policy Text Block] Average Rate Reduction Financing Receivable, Modifications, Average Rate Reduction Financing Receivable, Modifications, Average Rate Reduction Litigation Case [Axis] Litigation Case [Axis] Net unrealized gains (losses) on hedging relationships Net unrealized gains (losses) on hedging relationships Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax Term Extension Extended Maturity [Member] Penalty Paid to the US Treasury Penalty Paid to the US Treasury Penalty Paid to the US Treasury Equity investments subject to Impairment Investments in Affiliates, Subsidiaries, Associates, and Joint Ventures, Fair Value Disclosure-Subject to Impairment Investments in Affiliates, Subsidiaries, Associates, and Joint Ventures, Fair Value Disclosure- Subject to Impairment Total other VIEs Nonsecuritization-Related Variable Interest Entities [Member] Nonsecuritization-Related Variable Interest Entities Loans held for investment Gain (Loss) On Fair Value Loans Held For Investment Recognized In Earnings Gain (Loss) On Fair Value Loans Held For Investment measured on nonrecurring basis Short-term Debt, Type [Axis] Short-term Debt, Type [Axis] Liabilities: Liabilities [Abstract] Counterparty Name [Domain] Counterparty Name [Domain] Intangible assets, gross (excluding Goodwill) Intangible Assets, Gross (Excluding Goodwill) Depositary Shares, Each Representing a 1/40th Interest in a Share of Fixed Rate Non-Cumulative Perpetual Preferred Stock, Series K Series K Preferred Stock Series K Preferred Stock [Member] Outstanding nonredeemable series K preferred stock or outstanding series K preferred stock. Classified within stockholders' equity if nonredeemable or redeemable solely at the option of the issuer. Classified within temporary equity if redemption is outside the control of the issuer. Weighted average Weighted Average [Member] Commercial MSRs, gross Mortgage Servicing Asset at Amortized Cost, Gross Mortgage Servicing Asset at Amortized Cost, Gross Affordable housing entities Affordable Housing Entities [Member] The Company invests in affordable housing properties. Affordable housing VIEs can be corporations, partnerships, trusts, or any other legal structure used for investing in affordable housing properties. The Company consolidates those VIEs in which it has a variable interest, power to direct significant activities of the VIE, and obligation to absorb losses or right to receive benefits that could be significant to the VIE. The Company's exposure to losses is limited to its variable interests. Income from continuing operations before income taxes Income from continuing operations before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Level 2 Fair Value, Inputs, Level 2 [Member] Interest income - Loans Interest income - Loans [Member] Interest income - Loans [Member] Credit Score, FICO [Axis] Credit Score, FICO [Axis] Geographic Distribution [Domain] Geographic Distribution [Domain] Components of Goodwill, Intangible Assets and MSRs Schedule of Intangible Assets and Goodwill [Table Text Block] Fair Value - Total Debt Securities, Available-for-sale, Unrealized Loss Position Segment Reporting [Abstract] Segment Reporting [Abstract] Financing Receivable, Credit Quality Indicator [Line Items] Financing Receivable, Credit Quality Indicator [Line Items] Amortized Cost Debt Securities, Available-for-sale, Amortized Cost Commodity contracts Commodity Contract [Member] Equity securities Equity Securities, Fair Value Disclosure Equity Securities Classified as Other Assets, Fair Value Disclosure Use of Estimates Use of Estimates, Policy [Policy Text Block] Schedule of Computation of Basic and Diluted Earnings Per Common Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Liabilities: Financial Liabilities Fair Value Disclosure [Abstract] Domestic Credit Card and Commercial Banking Portfolios [Member] Domestic Credit Card and Commercial Banking Portfolios [Member] Domestic Credit Card and Commercial Banking Portfolios Other comprehensive income (loss), net of tax Other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Schedule of Assets Measured at Fair Value on Nonrecurring Basis Fair Value Measurements, Nonrecurring [Table Text Block] Net Exposure Derivative Asset, Fair Value, Amount Offset Against Collateral Common stock, shares authorized Common Stock, Shares Authorized Net unrealized gains (losses) on securities available for sale Other Comprehensive Income (Loss), Available-for-sale Securities, Tax, Portion Attributable to Parent Maturities and paydowns of securitized debt obligations Repayments of Secured Debt Net income (loss) available to common stockholders Net income (loss) available to common stockholders Net Income (Loss) Available to Common Stockholders, Basic Product and Service [Domain] Product and Service [Domain] Securities available for sale, amortized cost Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss Stated interest rates Debt Instrument, Interest Rate, Stated Percentage Hedged Assets, Fair Value Hedge, Cumulative Increase (Decrease) Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease) Total assets of the unconsolidated VIE investment funds Variable Interest Entity, Nonconsolidated, Total Assets Variable Interest Entity, Nonconsolidated, Total Assets Weighted-average expected life Debt Maturities, Available-for-Sale, Weighted Average Expected Life Debt Maturities, Available-for-Sale, Weighted Average Expected Life 1.650% Senior Notes Due 2029 Senior Notes Due 2029 [Member] 1.650% Senior Notes Due 2029 Measurement Frequency [Axis] Measurement Frequency [Axis] Total non-interest income Non-interest income (loss) Non-interest income (loss) Noninterest Income Credit Card Credit Card Segment [Member] Credit Card Segment Geographical [Axis] Geographical [Axis] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Other Other Investments [Member] Interest-bearing deposits and other short-term investments Interest-bearing Deposits in Banks and Other Financial Institutions Net investment hedges Net investment hedges Net Investment Hedging [Member] Hedging Relationship [Axis] Hedging Relationship [Axis] Weighted average interest rate Long-term Debt, Weighted Average Interest Rate, at Point in Time Class of Securities [Axis] Class of Securities [Axis] Class of Securities Derivative, collateral, right to reclaim cash Derivative, Collateral, Right to Reclaim Cash Percentage, 90 Days Past Due and Accruing Financing Receivable, Percent 90 Days Past Due and Still Accruing Financing Receivable, Percent 90 Days Past Due and Still Accruing Net cash from financing activities Net Cash Provided by (Used in) Financing Activities Service charges and other customer-related fees Service Charges And Other Customer Fees, Contracts [Member] Service Charges And Other Customer Fees, Contracts [Member] Fair Value Measurement Fair Value Disclosures [Text Block] Total Loans Financing Receivable, Troubled Debt Restructuring, Subsequent Default Cash and due from banks Cash and Due from Banks Concentration Risk Type [Axis] Concentration Risk Type [Axis] Financial Instrument Performance Status [Axis] Financial Instrument Performance Status [Axis] Entities [Table] Entities [Table] Increase (Decrease) in Allowance for Credit Loss Increase (Decrease) in Allowance for Credit Loss Increase (Decrease) in Allowance for Credit Loss VIE, nonconsolidated, carrying amount of liabilities included in certain investment structures Variable Interest Entities, nonconsolidated, Carrying amount of liabilities included in certain investment structures In certain investment structures, we consolidate a VIE which in turn holds as its primary asset an investment in an unconsolidated VIE. This concept represents the carrying amount of liabilities related to these investment structures. Available-for-sale securities Available-for-sale Securities [Member] Accounting for Acquisitions Business Combinations Policy [Policy Text Block] Hedged Item in Fair Value Hedging Relationship Hedged Item in Fair Value Hedging Relationship [Table Text Block] Table shows the carrying amount and associated cumulative basis adjustment related to the application of hedge accounting that is included in the carrying amount of hedged assets and liabilities in fair value hedging relationships. Net income (expense) recognized on cash flow hedges Gain (Loss) On Cash Flow Hedges Recognized In Earnings Total amount of gain (loss) derived from cash flow hedges recognized in earnings in the period Net exposure Derivative Liability, Fair Value, Amount Offset Against Collateral Revolving loans converted to term during period Financing Receivable, Revolving, Converted to Term Loan During Period Interest income: Interest and Dividend Income, Operating [Abstract] Depositary Shares, Each Representing a 1/40th Interest in a Share of Fixed Rate Non-Cumulative Perpetual Preferred Stock, Series N Series N Preferred Stock [Member] Series N Preferred Stock [Member] Series N Preferred Stock Litigation settlement, attributable to reporting entity and third party Litigation Settlement, Amount Attributable to Reporting Entity and Third Party Litigation Settlement, Amount Attributable to Reporting Entity and Third Party Long lived assets held for sale Assets Held-for-sale, Long Lived, Fair Value Disclosure Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Consolidated Entities [Domain] Consolidated Entities [Domain] Allowance build (release) for credit losses Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease) Income Statement Location [Domain] Income Statement Location [Domain] Intangible Assets by Major Class [Domain] Intangible Assets by Major Class [Domain] Intangible Assets by Major Class [Domain] Other investments Investments, Fair Value Disclosure Non-cash items: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Loans held for investment: Loans and Leases Receivable, Net Amount [Abstract] Retained interests in securitizations Retained Interest, Fair Value Disclosure Unfunded lending commitments, contractual amount Letter of Credit Issued Contractual Amount and Unused Commitment to Extend Credit Letter of credit issued contractual amount and unused commitment to extend credit Net derivative assets (liabilities), measurement input Derivative Asset (Liability) Net, Measurement Input Interest receivable Interest Receivable Premises and equipment, net Property, Plant and Equipment, Net Dividends, preferred stock Dividends, Preferred Stock, Cash Commitments to lend on loans modified in TDRs Financing Receivable, Troubled Debt Restructuring, Commitment to Lend Provision (Benefit) Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent, Parenthetical Disclosures [Abstract] Liquidation Preference per Share Preferred Stock, Redemption Price Per Share Total Gains or (Losses) (Realized/Unrealized), Included in OCI Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) Earnings Per Share [Abstract] Earnings Per Share [Abstract] Other Accumulated Other Comprehensive Income (Loss), Other Component [Member] Accumulated other comprehensive income or loss from pension, other postretirement benefit plans, and others. Total cash and cash equivalents Cash, Cash Equivalents, and Federal Funds Sold Foreign currency translation adjustments Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent Purchases Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Purchases Total net revenue (loss) Revenues Amounts reclassified from AOCI into earnings Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Foreign exchange contracts Foreign Exchange Contract [Member] Treasury stock, at cost (par value $0.01 per share; 254,139,961 and 220,960,635 shares as of September 30, 2021 and December 31, 2020, respectively) Treasury Stock, Common, Value Loss contingency accrual Loss Contingency Accrual Income (loss) from discontinued operations Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Interest-bearing deposits Interest-bearing Deposit Liabilities Net unrealized gains (losses) on hedging relationships Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax Life of receivables (months) Measurement Input, Life of Receivables [Member] Measurement input using life of receivables Number of securities in gross unrealized loss positions Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions Originations and purchases Payments for Origination and Purchases of Loans Held-for-sale Default rate Measurement Input, Default Rate [Member] Issuance of senior and subordinated notes and long-term FHLB advances Proceeds from Issuance of Unsecured Debt and Long Term FHLB Advances, Net of Issuance Cost Proceeds from issuance of senior and sub notes and long term FHLB advances, Net of Issuance Cost Document Fiscal Period Focus Document Fiscal Period Focus Loss contingency, estimate of possible loss Loss Contingency, Estimate of Possible Loss Depositary Shares, Each Representing a 1/40th Interest in a Share of Fixed Rate Non-Cumulative Perpetual Preferred Stock, Series J Series J Preferred Stock Series J Preferred Stock [Member] Outstanding nonredeemable series J preferred stock or outstanding series J preferred stock. Classified within stockholders' equity if nonredeemable or redeemable solely at the option of the issuer. Classified within temporary equity if redemption is outside the control of the issuer. Other securities Other Debt Obligations [Member] Counterparty Name [Axis] Counterparty Name [Axis] Beginning balance (shares) Ending balance (shares) Shares, Issued United States UNITED STATES Discount rate Measurement Input, Discount Rate [Member] Variable Interest Entities and Securitizations Variable Interest Entity Disclosure [Text Block] PPP loans Financing Receivable Past Due And Not Past Due Under Paycheck Protection Program Financing receivable past due and not past due under paycheck protection program Changes in deposits Increase (Decrease) in Deposits Income Taxes Income Tax, Policy [Policy Text Block] Financing Receivable, Troubled Debt Restructuring [Line Items] Financing Receivable, Troubled Debt Restructuring [Line Items] Series E Preferred Stock Series E Preferred Stock [Member] Derivative liabilities, gross amount Derivative liabilities, gross amount Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement Goodwill and Other Intangible Assets Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block] Securitized debt obligations Securitized debt obligations Interest Expense, Secured Debt Interest Expense, Secured Debt Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Total non-interest expense Non-interest expense Noninterest Expense Underlying Asset Class [Domain] Underlying Asset Class [Domain] Total weighted-average diluted common shares outstanding Weighted Average Number of Shares Outstanding, Diluted Net amounts as recognized Securities Sold under Agreements to Repurchase Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Derivative assets, securities not netted Derivative Asset, Fair Value of Collateral Due in 1 year or less Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Amortized Cost 90 Plus Day Delinquent Loans Accruing Interest and Nonperforming Loans Financing Receivable, Nonaccrual [Table Text Block] Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] VIE, reporting entity involvement, maximum loss exposure Maximum Exposure to Loss Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount Net loans held for investment Loans Receivable, Fair Value Disclosure Class of Stock [Line Items] Class of Stock [Line Items] Occupancy and equipment Occupancy, Net Credit Facility [Axis] Credit Facility [Axis] Derivatives not designated as accounting hedges Not Designated as Hedging Instrument [Member] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Changes in other borrowings Proceeds from (Repayments of) Other Debt Allowance for Credit Losses Financing Receivable, Allowance for Credit Losses, Policy for Uncollectible Amounts [Policy Text Block] Net unrealized gains on securities available for sale Net unrealized gains (losses) on securities available for sale Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent Operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Principles of Consolidation Consolidation, Policy [Policy Text Block] Total Gain (Loss) On Fair Value Assets Recognized In Earnings Gain (Loss) On Fair Value Assets measured on nonrecurring basis Gains (losses) recognized on hedged items Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge Litigation Status [Domain] Litigation Status [Domain] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Loss Contingencies [Table] Loss Contingencies [Table] Reclassification out of Accumulated Other Comprehensive Income [Member] Reclassification out of Accumulated Other Comprehensive Income [Member] Non interest income - Other Non Interest Income Other [Member] Non Interest Income Other Member Entity Address, Postal Zip Code Entity Address, Postal Zip Code Carrying Amount of Assets Carrying Amount Of Assets Carry amount of assets hedged in fair value hedging relationship Derivative, collateral, obligation to return securities Derivative, Collateral, Obligation to Return Securities Total loans held for investment Financing Receivable, before Allowance for Credit Loss Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [Table] Derivative, Fair Value, Net [Abstract] Derivative, Fair Value, Net [Abstract] Title of 12(b) Security Title of 12(b) Security Term loans by vintage year three Financing Receivable, Excluding Accrued Interest, Year Three, Originated, Two Years before Current Fiscal Year Statement [Table] Statement [Table] Other borrowings Interest Expense Other Borrowings Interest expense incurred during the reporting period on other borrowings. Collaborative Arrangement and Arrangement Other than Collaborative [Table] Collaborative Arrangement and Arrangement Other than Collaborative [Table] New Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Current Financial Asset, Current And Less Than 30 Days Past Due [Member] Financial Asset, Current And Less Than 30 Days Past Due [Member] Credit Card and Consumer Banking Credit Card and Consumer Portfolios [Member] Credit Card and Consumer Portfolios [Member] Preferred Stock, Including Additional Paid in Capital, Net of Discount Preferred Stock, Including Additional Paid in Capital, Net of Discount Components of Other Comprehensive Income (Loss) and Related Tax Impact Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] Interest expense - Senior and Subordinated Debt Interest expense - Senior and Subordinated Debt [Member] Interest expense - Senior and Subordinated Debt [Member] Statistical Measurement [Axis] Statistical Measurement [Axis] Finance charge and fee reserve reclassification Reclassification, Other [Member] Cover [Abstract] Cover [Abstract] Receivables in the trust, non-mortgage Continuing Involvement with Continued to be Recognized Transferred Financial Assets, Amount Outstanding Goodwill Balance as of December 31, 2020 Balance as of September 30, 2021 Goodwill 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] Derivative assets Offsetting Derivative Assets [Abstract] Gross Unrealized Loss - Less than 12 Months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Common stock: Common Stock, Financing Activities [Abstract] Common Stock, Financing Activities [Abstract] Foreclosed property and repossessed assets, fair value disclosure Foreclosed Property and Repossessed Assets, Fair Value Disclosure Foreclosed property and repossessed assets, fair value disclosure Goodwill by Business Segments Schedule of Goodwill [Table Text Block] Total Total Total Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss Schedule of Intangible Assets by Major Class [Line Items] Schedule of Intangible Assets by Major Class [Line Items] [Line Items] for Schedule of Intangible Assets by Major Class [Table] Schedule of Derivative Assets and Liabilities at Fair Value Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Loans Pledged as Collateral Loans Pledged as Collateral Geographic Distribution [Axis] Geographic Distribution [Axis] Gain on sales of loans Gain (Loss) on Sales of Loans, Net Gross Unrealized Loss - 12 Months or Longer Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] Deferred tax provision (benefit) Deferred Income Tax Expense (Benefit) Cybersecurity Incident Cybersecurity Incident [Member] Cybersecurity Incident [Member] Deposits Deposits Interest Expense, Deposits Financial assets: Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract] Hedging Designation [Domain] Hedging Designation [Domain] Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] RMBS, Non-agency Residential Mortgage Backed Securities, Non-agency [Member] Securities collateralized by non-agency residential real estate mortgage loans. Net income Net income (loss) Net Income (Loss) Attributable to Parent Entity Emerging Growth Company Entity Emerging Growth Company Non-interest-bearing deposits Noninterest-bearing Deposit Liabilities Income Statement Location [Axis] Income Statement Location [Axis] Interest rate contracts Interest Rate Contract [Member] Customer Rewards Reserve cof_Customer Rewards Reserve Policy Text Block [Policy Text Block] cof_Customer Rewards Reserve Policy Text Block Statistical Measurement [Domain] Statistical Measurement [Domain] Accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization Entity Address, Address Line One Entity Address, Address Line One 621-660 FICO Score 621 To 660 [Member] FICO Score 621 To 660 [Member] Offsetting Assets Offsetting Assets [Table Text Block] Restricted cash for securitization investors Restricted Cash and Cash Equivalents, Fair value Disclosure Restricted Cash and Cash Equivalents, Fair value Disclosure Entity Filer Category Entity Filer Category Series M Preferred Stock Series M Preferred Stock [Member] Outstanding nonredeemable series M preferred stock or outstanding series M preferred stock. Classified within stockholders' equity if nonredeemable or redeemable solely at the option of the issuer. Classified within temporary equity if redemption is outside the control of the issuer. Segments [Axis] Segments [Axis] Compensation expense for restricted stock units and stock options APIC, Share-based Payment Arrangement, Increase for Cost Recognition Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value Investments in Debt and Equity Instruments, Cash and Cash Equivalents, Unrealized and Realized Gains (Losses) Investments in Debt and Equity Instruments, Cash and Cash Equivalents, Unrealized and Realized Gains (Losses) [Text Block] Valuation Approach and Technique [Domain] Valuation Approach and Technique [Domain] Total long-term debt Long-term Debt and Lease Obligation Financial Asset, Past Due Financial Asset, Past Due [Member] Underlying Asset Class [Axis] Underlying Asset Class [Axis] Hedged Liabilities, Fair Value Hedge, Cumulative Increase (Decrease) Hedged Liability, Fair Value Hedge, Cumulative Increase (Decrease) Provision (benefit) for credit losses Financing Receivable, Credit Loss, Expense (Reversal) Maturities and paydowns of senior and subordinated notes and long-term FHLB advances Repayments of Unsecured Debt and Long Term FHLB Advances The cash outflow to repay senior and subordinated notes and long term FHLB Advances. Hedged Liabilities, Discontinued Fair Value Hedge, Cumulative Increase (Decrease) Hedged Liability, Discontinued Fair Value Hedge, Cumulative Increase (Decrease) Securities available-for-sale, measurement input Debt Securities, Available-for-sale, Measurement Input Proceeds from paydowns and maturities Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-sale Gains (losses) on derivatives not designated as accounting hedges Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net Credit Facility [Domain] Credit Facility [Domain] Assets: Assets [Abstract] Small-ticket commercial real estate Small Ticket Real Estate [Member] Loans issued to businesses to acquire, develop, construct, improve, or refinance land or a building. Includes but is not limited to commercial mortgage loans and construction financing. Derivative Instruments and Hedging Activities Derivative Instruments and Hedging Activities Disclosure [Text Block] ICFR Auditor Attestation Flag ICFR Auditor Attestation Flag Goodwill and Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Percentage of portfolio Concentration Risk, Percentage Premises and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Hedged assets cumulative basis adjustment Hedged LOLA Assets Cumulative Basis Adjustment Hedged assets fair value hedge cumulative increase decrease - LOLA Loss sharing agreements Loss sharing agreements Loss Sharing Agreement [Member] Loss Sharing Agreement [Member] Entity Address, City or Town Entity Address, City or Town Amortization method qualified affordable housing investments Amortization Method Qualified Affordable Housing Project Investments Debt Instrument [Axis] Debt Instrument [Axis] Revolving loans Financing Receivable, Excluding Accrued Interest, Revolving Marketing Expenses Advertising Cost [Policy Text Block] Financial Asset, Period Past Due [Domain] Financial Asset, Aging [Domain] Reserve for unfunded lending commitments Unfunded Loan Commitment [Member] Allowance for credit losses Allowance for credit loss Financing Receivable, Allowance for Credit Loss, Beginning Balance Balance at the end of the period Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest Interest expense - Deposits Interest expense - Deposits [Member] Interest expense - Deposits [Member] Securitized debt obligations Secured Debt [Member] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Internal Credit Assessment [Domain] Internal Credit Assessment [Domain] Number of consumer class action cases currently pending for cybersecurity incident Number of Consumer Class Action Cases Currently Pending for Cybersecurity Incident Number of Consumer Class Action Cases Currently Pending for Cybersecurity Incident Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Entity Interactive Data Current Entity Interactive Data Current Off-balance sheet lending commitment, carrying value Off-Balance Sheet Lending Commitment Carrying Value The carrying value of off-balance sheet lending-related financial instruments (e.g., commitments and guarantees), which represents the allowance for lending-related commitments, deferred revenue and the guarantee liability. Line of Credit Facility, Remaining Borrowing Capacity Line of Credit Facility, Remaining Borrowing Capacity Number of operating segments Number of Operating Segments Treasury stock, par value (in dollars per share) Treasury Stock Par Or Stated Value Per Share Treasury Stock Par Or Stated Value Per Share Securitized debt obligations Securitized Debt Obligations [Member] securitized debt obligations [Member] US Treasury and Agency securities US Treasury and Government [Member] Repurchase agreements, securities collateral not netted Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Securities Interest receivable Interest Receivable, Fair Value Disclosure This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure and may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. This item represents interest earned but not received as of the balance sheet date. 90 Days Past Due and Accruing Financing Receivable, 90 Days or More Past Due, Still Accruing Senior and subordinated notes Senior and subordinated notes Interest Expense, Unsecured Debt Interest expense incurred during the reporting period on senior and subordinated notes. Retained interests, measurement input, life of receivables Retained Interest, Measurement Input, Life of Receivables Retained Interest, Measurement Input, life of receivables Total Shares Outstanding as of September 30, 2021 Preferred Stock, Depositary Shares Issued Preferred Stock, Depositary Shares Issued Intangible Assets by Major Class [Axis] Intangible Assets by Major Class [Axis] Intangible Assets by Major Class [Axis] Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Number of Contracts Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts Net derivative assets (liabilities) Net Derivative Assets (Liabilities) [Member] Net Derivative Assets (Liabilities) Expected reimbursement from loss sharing partners, beginning balance Expected reimbursement from loss sharing partners, ending balance Loss Sharing Agreements, Financing Receivable, Allowance, Covered, Expected Reimbursement Loss Sharing Agreements, Financing Receivable, Allowance, Covered, Expected Reimbursement Repurchase agreements Offsetting Securities Sold under Agreements to Repurchase [Abstract] Financial Instrument Performance Status [Domain] Financial Instrument Performance Status [Domain] Per Annum Dividend Rate Preferred Stock, Dividend Rate, Percentage Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax, Portion Attributable to Parent Hedged Assets, Discontinued Fair Value Hedge, Cumulative Increase (Decrease) Hedged Asset, Discontinued Fair Value Hedge, Cumulative Increase (Decrease) Non-interest income: Noninterest Income [Abstract] Revenue (reduction) from other sources Noninterest Income, Excluding Revenue From Contract With Customer Noninterest Income, Excluding Revenue From Contract With Customer Goodwill [Roll Forward] Goodwill [Roll Forward] Transfers Out of Level 3 Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers out of Level 3 Securitized debt obligations Secured Debt, Fair Value Disclosure Secured Debt, Fair Value Disclosure Net income (loss) from continuing operations Net income (loss) from continuing operations (in dollars per share) Income (Loss) from Continuing Operations, Per Diluted Share Financing Receivable Portfolio Segment [Axis] Financing Receivable Portfolio Segment [Axis] Total assets Assets, Fair Value Disclosure Net interest income after provision for credit losses Interest Income (Expense), after Provision for Loan Loss Document Transition Report Document Transition Report Greater than 660 FICO Score Greater Than 660 [Member] FICO Score Greater Than 660 [Member] Securities available for sale: Proceeds from Sale and Maturity of Debt Securities, Available-for-sale [Abstract] Financial liabilities: Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract] Total liabilities and stockholders’ equity Liabilities and Equity Time deposits, at or above FDIC insurance limit Time Deposits, at or Above FDIC Insurance Limit Term loans by vintage year two Financing Receivable, Excluding Accrued Interest, Year Two, Originated, Fiscal Year before Current Fiscal Year Investments, Debt and Equity Securities [Abstract] Investments, Debt and Equity Securities [Abstract] Exercises of stock options (shares) Stock Issued During Period, Shares, Stock Options and Warrants Exercised and Restricted Stock Vesting Stock Issued During Period, Shares, Stock Options and Warrants Exercised and Restricted Stock Vesting Income (loss) from discontinued operations Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share Qualified affordable housing investments, commitment Qualified Affordable Housing Project Investments, Commitment Balance Sheet Offsetting of Financial Assets and Liabilities Derivatives, Offsetting Fair Value Amounts, Policy [Policy Text Block] Past due, percentage of total loans Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent, Percent Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent, Percent Due after 5 years through 10 years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Fair Value Concentration Risk [Line Items] Concentration Risk [Line Items] Fixed unsecured senior debt Fixed Unsecured Senior Debt [Member] Fixed unsecured senior debt. Short-term Debt, Type [Domain] Short-term Debt, Type [Domain] Earnings Per Common Share Earnings Per Share [Text Block] Purchases of treasury stock Treasury Stock, Value, Acquired, Cost Method Minimum Minimum Minimum [Member] Net valuation allowance on derivative assets and liabilities for non-performance risk Net valuation allowance Derivative Credit Risk Valuation Adjustment, Derivative Assets (Liabilities) Derivative Credit Risk Valuation Adjustment, Derivative Assets (Liabilities) Total commercial lending Commercial Lending [Member] Commercial Lending [Member] Other comprehensive income (loss), net of tax: After Tax Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Preferred stock, shares authorized Preferred Stock, Shares Authorized Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net Gain (Loss) from Components Excluded from Assessment of Fair Value Hedge Effectiveness, Net Retained interest in securitizations Retained Interest [Member] Cumulative Effect, Period of Adoption [Axis] Cumulative Effect, Period of Adoption [Axis] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value - 12 Months or Longer Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer Qualitative and Quantitative Information, Transferor's Continuing Involvement [Table] Qualitative and Quantitative Information, Transferor's Continuing Involvement [Table] Issuances of preferred stock Stock Issued During Period, Value, New Issues Net cash from acquisition activities Payments to Acquire Businesses, Net of Cash Acquired Foreign Currency Translation Adjustments Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Due in 1 year or less Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value Total securitization-related VIEs Securitization-Related Variable Interest Entities [Member] Securitization-Related Variable Interest Entities Senior notes Senior Notes [Member] Level 3 Fair Value, Inputs, Level 3 [Member] Dividends paid Payments of Ordinary Dividends, Common Stock Leases Lessee, Leases [Policy Text Block] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Issuances of preferred stock (shares) Stock Issued During Period, Shares, New Issues Interest recognized on derivatives Gain Or Loss On Fair Value Hedges Recognized In Net Interest Income Gain or loss on fair value hedges recognized in net interest income Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Acquisitions Goodwill, Acquired During Period Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Commitments, contingencies and guarantees (see Note 13) Commitments and Contingencies Revenue change due to impact of federal tax rate Revenue Change Due To Impact Of Federal Tax Rate And Measurement Change Revenue Change Due To Impact Of Federal Tax Rate And Measurement Change Accumulated other comprehensive income AOCI beginning balance AOCI ending balance Accumulated Other Comprehensive Income (Loss), Net of Tax Receivables [Abstract] Receivables [Abstract] Net changes in loans held for investment Payments For (Proceeds From) Sale Of Financing Receivable, Held-For-Investment Payments For (Proceeds From) Sale Of Financing Receivable, Held-For-Investment Document Period End Date Document Period End Date Schedule Of Expected Maturity And Weighted Average Yield Of Securities [Table] Schedule Of Expected Maturity And Weighted Average Yield Of Securities [Table] Schedule of expected maturity and weighted average yield of securities. Other comprehensive income (loss) before reclassifications Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Cumulative Effect, Period of Adoption, Adjusted Balance Cumulative Effect, Period of Adoption, Adjusted Balance [Member] Entity Registrant Name Entity Registrant Name Financing Receivable, Credit Quality Indicator [Table] Financing Receivable, Credit Quality Indicator [Table] Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Percentage, Nonperforming Loans Financing Receivable, Nonaccrual, Percent Past Due Hedged Items In Fair Value Hedging Relationship [Line Items] Hedged Items In Fair Value Hedging Relationship [Line Items] [Line Items] for Table shows the carrying amount and associated cumulative basis adjustment related to the application of hedge accounting that is included in the carrying amount of hedged assets and liabilities in fair value hedging relationships. Net change from discontinued operations Cash Provided by (Used in) Operating Activities, Discontinued Operations CALIFORNIA CALIFORNIA Domestic credit card: Geographic Distribution, Domestic [Member] Professional services Professional and Contract Services Expense Loans held for investment, measurement input Loans Held for Investment, Measurement Input Loans held for investment, measurement input Financial Instrument [Axis] Financial Instrument Financial Instrument [Axis] Short-term borrowings Short-term Debt [Line Items] Securities available for sale (amortized cost of $97.0 billion and $97.6 billion and allowance for credit losses of $1 million as of both September 30, 2021 and December 31, 2020) Fair Value Securities available for sale Debt Securities, Available-for-Sale, Excluding Accrued Interest Finance lease liabilities Capital Lease Obligations [Member] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Issuances of common stock and restricted stock, net of forfeitures (shares) Stock Issued During Period, Shares, New Issues and Restricted Stock, Net of Forfeitures (in shares) Stock Issued During Period, Shares, New Issues and Restricted Stock, Net of Forfeitures Derivative assets, gross amount Derivative assets, gross amount Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement Carrying Value Reported Value Measurement [Member] Net unrealized gains (losses) on securities available for sale Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, Portion Attributable to Parent Advised line of credit Advised Line of Credit The contractual amount of line of credit that drawings are subject to our satisfactory evaluation of the customer and are cancelable upon proper notice. Commercial Banking Commercial Banking Segment [Member] Consists of lending, deposit gathering and treasury management services to commercial real estate and middle market customers. Our Commercial Banking business results also include the results of a national portfolio of small ticket commercial real-estate loans that are in run-off mode. Common Stock (par value $.01 per share) Common Stock Common Stock [Member] Derivative liabilities Offsetting Derivative Liabilities [Abstract] Financial Asset, Period Past Due [Axis] Financial Asset, Aging [Axis] Gross Unrealized Losses Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Summary of Significant Accounting Policies Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] Percentage of total loans Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Percent, Total Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Percent, Total Treasury stock, shares Treasury Stock, Common, Shares Hedging Designation [Axis] Hedging Designation [Axis] Total unsecured senior debt Unsecured Senior Debt [Member] Unsecured senior debt. Stock-based compensation expense Share-based Payment Arrangement, Noncash Expense Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward] AOCI Attributable to Parent, Net of Tax [Roll Forward] Allowance for Credit Losses and Reserve for Unfunded Lending Commitment Allowance for Credit Losses [Text Block] Other comprehensive income (loss), provision (benefit) Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent Issuances Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Issues Treasury Stock Treasury Stock [Member] Purchases Payments to Acquire Debt Securities, Available-for-sale Collaborative Arrangement and Arrangement Other than Collaborative [Domain] Collaborative Arrangement and Arrangement Other than Collaborative [Domain] Schedule of Earnings Related to Assets Measured at Fair Value on Nonrecurring Basis Fair Value Assets Measured On Non Recurring Basis Gain Loss Included In Earnings [Table Text Block] Fair Value Assets Measured On Non Recurring Basis Gain Loss Included In Earnings [Table Text Block] Income tax paid Income Taxes Paid Derivative liabilities, securities collateral not netted Derivative Liability, Fair Value of Collateral Notional or contractual amount Derivative, Notional Amount Net purchases of premises and equipment Payments to Acquire Property, Plant, and Equipment Valuation Approach and Technique [Axis] Valuation Approach and Technique [Axis] Amortization method qualified affordable housing investments, amortization Amortization Method Qualified Affordable Housing Project Investments, Amortization Preferred stock dividends Preferred Stock Dividends, Income Statement Impact Entity Information [Line Items] Entity Information [Line Items] Amortized cost of closed prepayment assets Amortized Cost of Closed Prepayment Assets Amortized cost of closed prepayment assets for LOLA hedging purpose Total liabilities Carrying Amount of Liabilities Liabilities Internal Credit Assessment [Axis] Internal Credit Assessment [Axis] Interest income - Investment securities Interest income - Investment securities [Member] Interest income - Investment securities [Member] Measurement Input Type [Axis] Measurement Input Type [Axis] Consolidation Items [Axis] Consolidation Items [Axis] Common stock, shares issued Common Stock, Shares, Issued Security Owned and Pledged as Collateral, Fair Value Security Owned and Pledged as Collateral, Fair Value Preferred stock, shares issued Preferred Stock, Shares Issued Other Other Comprehensive Income (Loss), Other Tax, Attributable To Parent Other Comprehensive Income (Loss), Other Tax, Attributable To Parent Securities held by third-party investors, non-mortgage Continuing Involvement with Continued to be Recognized Transferred Financial Assets, Liabilities Incurred Continuing Involvement with Continued to be Recognized Transferred Financial Assets, Liabilities Incurred Federal Reserve Discount Window Federal Reserve Discount Window [Member] Federal Reserve Discount Window [Member] Due > 5 Years through 10 Years Debt Securities, Available-for-sale, Maturity, Rolling after Five Through Ten Years, Weighted Average Yield Loss severity Measurement Input, Loss Severity [Member] Variable Interest Entities Consolidation, Variable Interest Entity, Policy [Policy Text Block] Change in AOCI Gain (Loss) by Component (Net of Tax) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Schedule Of Expected Maturity And Weighted Average Yield Of Securities [Line Items] Schedule Of Expected Maturity And Weighted Average Yield Of Securities [Line Items] Schedule of expected maturity and weighted average yield of securities line items. Performing Criticized performing Performing Financial Instruments [Member] Service charges and other customer-related fees Service Charges and Other Customer-Related Fees Amount of income earned from loan services (including debt and credit protection, over limit, membership and annual fees). Excludes interest income earned on credit card balances and transactions. Balance Sheet Location [Axis] Balance Sheet Location [Axis] Schedule of Short-term Debt [Table] Schedule of Short-term Debt [Table] Measurement Frequency [Domain] Measurement Frequency [Domain] Loan Restructuring Modification [Domain] Loan Restructuring Modification [Domain] Senior and subordinated notes EUR denominated unsecured notes Unsecured Debt Due > 10 Years Debt Securities, Available-for-sale, Maturity, Rolling after 10 Years, Weighted Average Yield Total interest expense Interest expense Interest Expense Total interest income Interest and Dividend Income, Operating 60-89 days Financial Asset, 60 to 89 Days Past Due [Member] City Area Code City Area Code Retained earnings Retained Earnings (Accumulated Deficit) Entity Public Float Entity Public Float Litigation Case Litigation Case [Domain] Fair Value Measurement Inputs and Valuation Techniques [Table] Fair Value Measurement Inputs and Valuation Techniques [Table] Recoveries Financing Receivable, Allowance for Credit Loss, Recovery Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Number of consumer class action cases filed for Cybersecurity Incident Number of Consumer Class Action Cases Filed for Cybersecurity Incident Number of consumer class action cases filed for Cybersecurity Incident Gains (Losses) on Free-Standing Derivatives Derivative Instruments, Gain (Loss) [Table Text Block] Consumer MSRs Servicing Contracts [Member] U.S. Treasury securities US Treasury Securities [Member] Amendment Flag Amendment Flag Estimated Fair Value Estimate of Fair Value Measurement [Member] Repurchase agreements, securities sold, offset Securities Sold under Agreements to Repurchase, Asset Prepayable Financial Asset Closed Portfolio, Last-of-Layer, Amortized Cost Prepayable Financial Asset Closed Portfolio, Last-of-Layer, Amortized Cost Senior and subordinated notes Unsecured Debt, Fair Value Disclosure Unsecured Debt, Fair Value Disclosure Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Amortization expense (benefit) Amortization Of Basis Adjustment Amortization Of Basis Adjustment Commercial Banking Commercial Portfolio Segment [Member] Equity Components [Axis] Equity Components [Axis] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Hedging Relationships Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] Federal funds purchased and securities loaned or sold under agreements to repurchase Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Gains (losses) recognized on derivatives Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments Derivative assets, offsetting cash collateral Derivative Asset, Collateral, Obligation to Return Cash, Offset Schedule of Loss Sharing Arrangement Impact Schedule of Loss Sharing Arrangement Impact [Table Text Block] Schedule of loss sharing arrangement impact Concentration Risk Type [Domain] Concentration Risk Type [Domain] Effects from transfer of securities held to maturity to available for sale Other Comprehensive Income (Loss), Transfer of Securities Held to Maturity, Net of Tax Other Comprehensive Income (Loss), Transfer of Securities Held to Maturity, Net of Tax Sales Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales Schedule of Segment Results and Reconciliation Schedule of Segment Reporting Information, by Segment [Table Text Block] Communications and data processing Communications and Information Technology Other interest rate exposures Other Interest Rate Exposures [Member] Non-customer accommodation interest rate derivatives not designated as hedging instruments. Entity File Number Entity File Number Loans, including loans held for sale Interest and fee income, loans Interest and Fee Income, Loans and Leases 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] Settlements Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements Product and Service [Axis] Product and Service [Axis] Interest-bearing deposits Interest-bearing Deposits [Member] Preferred stock, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] CMBS, Agency Commercial Mortgage Backed Securities - Agency [Member] Commercial Mortgage Backed Securities - Agency [Member] Statement [Line Items] Statement [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Credit Quality Indicator Financing Receivable Credit Quality Indicators [Table Text Block] Total Gains or (Losses) (Realized/Unrealized), Included in OCI Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Other Comprehensive Income (Loss) Effects of Fair Value and Cash Flow Hedge Accounting Schedule of Derivatives Instruments Statements of Financial Performance and Financial Position, Location [Table Text Block] Current Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Current Debt Disclosure [Abstract] Other changes Financing Receivable, Allowance For Credit Loss, Adjustments, Other Financing Receivable, Allowance For Credit Loss, Adjustments, Other Entity Address, State or Province Entity Address, State or Province Non-interest expense: Noninterest Expense [Abstract] Other Corporate, Non-Segment [Member] Transfers Into Level 3 Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers into Level 3 Other Other Comprehensive Income (Loss), Before Tax, Attributable To Parent Other Comprehensive Income (Loss), Other, Before Tax, Attributable To Parent Preferred Stock, Dividend Payment Rate, Variable Preferred Stock, Dividend Payment Rate, Variable Other assets Gain (Loss) On Fair Value Other Assets Recognized In Earnings Gain (Loss) On Fair Value Other Assets measured on nonrecurring basis Entity Shell Company Entity Shell Company Local Phone Number Local Phone Number Reductions in goodwill related to divestitures Goodwill, Written off Related to Sale of Business Unit Gain (net after-tax) recorded in AOCI related to derivatives designated as cash flow hedges expected to be reclassified to earnings over the next 12 months Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months Net proceeds from issuances Proceeds from Issuance of Common Stock Total assets Carrying Amount of Assets Assets Interest paid Interest Paid, Excluding Capitalized Interest, Operating Activities Geographical [Domain] Geographical [Domain] Unsecuritized loans held for investment Parent Company [Member] Total term loans Financing Receivable, Excluding Accrued Interest, Before Allowance for Credit Loss, Term Loans Financing Receivable, Excluding Accrued Interest, Before Allowance for Credit Loss, Term Loans Depreciation and amortization, net Depreciation, Depletion and Amortization, Nonproduction Financing Receivable Portfolio Segment [Domain] Financing Receivable Portfolio Segment [Domain] Derivative Contract [Domain] Derivative Contract [Domain] Charge-offs Amounts due from partners which reduced net charge-offs Financing Receivable, Allowance for Credit Loss, Writeoff Redemptions of preferred stock (shares) Stock Redeemed or Called During Period, Shares Interchange fees, net Interchange Fees, Net Revenues earned from switch fees charged to financial institutions for accessing our network to process transactions and other fees, net of reward costs. Cumulative Effect, Period of Adoption [Domain] Cumulative Effect, Period of Adoption [Domain] All Currencies [Domain] All Currencies [Domain] Short-term borrowings Short-term Debt Net cash from operating activities Net Cash Provided by (Used in) Operating Activities Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Litigation Status [Axis] Litigation Status [Axis] Components of Deposits, Short-Term Borrowings and Long-Term Debt Schedule of Debt [Table Text Block] Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Entity Tax Identification Number Entity Tax Identification Number Basic earnings per common share: Earnings Per Share, Basic [Abstract] Debt and Equity Securities, Unrealized Gain (Loss) Debt and Equity Securities, Unrealized Gain (Loss) Total weighted-average basic common shares outstanding Weighted Average Number of Shares Outstanding, Basic Net income (loss) per diluted common share Net income (loss) per diluted common share (in dollars per share) Earnings Per Share, Diluted Effect of dilutive securities: Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract] Segments [Domain] Segments [Domain] Total effect of dilutive securities Weighted Average Number Diluted Shares Outstanding Adjustment Depository Share, Percent Interest in Preferred Stock Depository Share, Percent Interest in Preferred Stock Depository Share, Percent Interest in Preferred Stock Floating unsecured senior debt Floating Unsecured Senior Debt [Member] Floating unsecured senior debt. Retained interests, measurement input Retained Interest, Measurement Input Value of input used to measure portion of interest continued to be held by a transferor after transferring financial assets to a third party Intangible assets, net (excluding Goodwill) Intangible Assets, Net (Excluding Goodwill) Comprehensive income Comprehensive income (loss) Comprehensive Income (Loss), Net of Tax, Attributable to Parent Securities held by third-party investors, mortgage Continuing Involvement with Derecognized Transferred Financial Assets, Liabilities Incurred Continuing Involvement with Derecognized Transferred Financial Assets, Liabilities Incurred Net income (loss) from continuing operations Net income (loss) from continuing operations (in dollars per share) Income (Loss) from Continuing Operations, Per Basic Share Repurchase agreements, cash collateral pledged, offset Repurchase Agreement, Collateral, Right To Reclaim Cash, Offset Repurchase agreement, collateral, right to reclaim cash, offset 620 or below FICO Score, Less Than 620 [Member] FICO Score, Less Than 620 [Member] Total other long-term borrowings FHLB Advance Capital Lease Obligation and GPMH [Member] FHLB Advance Capital Lease Obligation and GPMH Loans held in consolidated trusts Consolidated Variable Interest Entity, Primary Beneficiary [Member] Term loans by vintage year one Financing Receivable, Excluding Accrued Interest, Year One, Originated, Current Fiscal Year Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Dividends, common stock Dividends, Common Stock Carrying Amount of Assets and Liabilities of Variable Interest Entities Schedule of Variable Interest Entities [Table Text Block] Accumulated Other Comprehensive Income (Loss) Total AOCI Attributable to Parent [Member] Other assets Other Assets Common stock, shares outstanding Common Stock, Shares, Outstanding Transfers Into Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 Subordinated notes Subordinated Debt [Member] Financial Instruments [Domain] Financial Instruments [Domain] Issuance cost for redeemed preferred stock Issuance Cost For Preferred Stock Redeemed Issuance cost for preferred stock redeemed Dividends, common stock (shares) Common Stock Dividends, Shares Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Combined allowance and reserve Combined Allowance And Unfunded Reserve [Member] Combined allowance and unfunded reserve. Reduced Interest Rate Contractual Interest Rate Reduction [Member] Financing Receivable, Past Due [Table] Financing Receivable, Past Due [Table] Maximum exercise price range (in dollars per share) Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit Class of Securities [Domain] Security Class [Domain] [Domain] for Security Class Auto Auto Automobile Loan [Member] PCCR intangibles Customer Relationships [Member] Equity investments accounted for under measurement alternative Investments in Affiliates, Subsidiaries, Associates, and Joint Ventures, Fair Value Disclosure Allowance for Credit Losses Debt Securities, Available-for-Sale, Amortized Cost, Allowance for Credit Loss, Excluding Accrued Interest Due in 1 Year or Less Debt Securities, Available-for-sale, Maturity, Rolling within One Year, Weighted Average Yield Loss Contingencies [Line Items] Loss Contingencies [Line Items] Interest income - Other Interest income - Other [Member] Interest income - Other [Member] Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract] Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract] Variable Interest Entities and Securitization [Abstract] Variable Interest Entities and Securitization [Abstract] Variable Interest Entities and Securitization [Abstract] RMBS Residential Mortgage Backed Securities [Member] Past due total, percentatge of total loans Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent, Percent, Total Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent, Percent, Total Derivative assets, offsetting financial instruments Derivative Asset, Fair Value, Gross Liability Consumer Banking Consumer Banking Segment [Member] Consists of our branch-based lending and deposit gathering activities for small business customers, as well as branch-based consumer deposit gathering and lending activities, national deposit gathering, national automobile lending, consumer mortgage lending and servicing activities. Federal funds purchased and securities loaned or sold under agreements to repurchase Federal Funds Purchased and Securities Sold under Agreements to Repurchase Loans held for sale ($1.7 billion and $596 million carried at fair value as of September 30, 2021 and December 31, 2020, respectively) Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance Debt Instrument [Line Items] Debt Instrument [Line Items] Issuances of common stock and restricted stock, net of forfeitures Stock Issued During Period, Value, New Issues and Restricted Stock, Net of Forfeitures Stock Issued During Period, Value, New Issues and Restricted Stock, Net of Forfeitures Securities sold under repurchase agreements, fair value of collateral Securities Sold under Agreements to Repurchase, Fair Value of Collateral Total derivative assets Derivative asset Derivative Asset Preferred Stock Dividend Rate, Variable Dividend Basis Spread On Variable Rate The percentage points added to the reference rate to compute the dividend rate. Document Quarterly Report Document Quarterly Report Gross Unrealized Loss - Total Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss Changes in other assets Increase (Decrease) in Other Operating Assets Net proceeds from issuances Proceeds from Issuance of Preferred Stock and Preference Stock Derivative liabilities, offsetting financial instruments Derivative Liability, Fair Value, Gross Asset Current, percentage of total loans Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Current, Percent, Total Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Current, Percent, Total Proceeds from sales Proceeds from Sale of Debt Securities, Available-for-sale Deposits: Deposits [Abstract] Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Percentage, Nonperforming Loans Without an Allowance Financing Receivable, Nonaccrual, No Allowance, Percent Past Due Financing Receivable, Nonaccrual, No Allowance, Percent Past Due Goodwill, gross Goodwill, Gross Total short-term borrowings and long-term debt Debt and Lease Obligation Weighted average yield for securities available for sale Available-for-sale Securities, Weighted Average Yield [Abstract] Available-for-sale Securities, Weighted Average Yield [Abstract] Depositary Shares, Each Representing a 1/40th Interest in a Share of Fixed Rate Non-Cumulative Perpetual Preferred Stock, Series L Series L Preferred Stock Series L Preferred Stock [Member] Outstanding nonredeemable series L preferred stock or outstanding series L preferred stock. Classified within stockholders' equity if nonredeemable or redeemable solely at the option of the issuer. Classified within temporary equity if redemption is outside the control of the issuer. Schedule of Goodwill [Table] Schedule of Goodwill [Table] Nonperforming Loans Without an Allowance Financing Receivable, Nonaccrual, No Allowance Interchange fees, net Interchange Fees, Contracts [Member] Interchange Fees, Contracts [Member] Total goodwill and other intangible assets, net carrying value Intangible Assets, Net (Including Goodwill) Salaries and associate benefits Labor and Related Expense Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Investments [Domain] Investments [Domain] Uncollectible portion of billed finance charges and fees Uncollectible Portion of Billed Finance Charges and Fees Uncollectible Portion of Billed Finance Charges and Fees Securities Received as Collateral Securities Received as Collateral Term loans by vintage after year five Financing Receivable, Excluding Accrued Interest, Originated, More than Five Years before Current Fiscal Year Cash, cash equivalents and restricted cash for securitization investors, beginning of the period Cash, cash equivalents and restricted cash for securitization investors, end of the period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Securities available for sale, allowance for credit loss Debt Securities, Available-for-sale, Allowance for Credit Loss Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Criticized Criticized [Member] Entity Central Index Key Entity Central Index Key Security Exchange Name Security Exchange Name Deposits with defined maturities Deposits with Defined Maturities Deposits with Defined Maturities, Fair Value Disclosure Credit Card Credit Card Portfolio Segment [Member] Credit Card Portfolio Segment [Member] Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Income (loss) from discontinued operations, net of tax Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent Retail banking Retail banking Retail Banking [Member] Any loan or extension of credit to an individual for personal, family, or household. Beginning balance Ending balance Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Recurring Fair Value, Recurring [Member] Unused commitments to extend credit, contractual amount Unused Commitments to Extend Credit Current Fiscal Year End Date Current Fiscal Year End Date Other assets: Other Assets, Fair Value Disclosure [Abstract] Other Assets, Fair Value Disclosure [Abstract] Stockholders' Equity Stockholders' Equity Note Disclosure [Text Block] Net income (expense) recognized on fair value hedges Gain (Loss) on Fair Value Hedges Recognized in Earnings Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Fair Value of Financial Instruments, Policy [Policy Text Block] Gross Balance Reduction Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down Revolving loans converted to term Financing Receivable, Excluding Accrued Interest, Revolving, Converted to Term Loan Before Tax Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent [Abstract] Net cash from investing activities Net Cash Provided by (Used in) Investing Activities Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Other borrowings Other Borrowings Fair Value Disclosure This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure and may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. This item represents the aggregate of other miscellaneous borrowings owed by the company as of the balance sheet date. Other contracts Other Contract [Member] Class of Stock [Domain] Class of Stock [Domain] Dividends paid Payments of Ordinary Dividends, Preferred Stock and Preference Stock Principal recoveries of loans previously charged off Proceeds, Financing Receivable, Previously Written Off, Recovery Euro Euro Member Countries, Euro Standby letters of credit and commercial letters of credit, contractual amount Line of Credit Facility, Maximum Borrowing Capacity Total commercial MSRs Servicing Asset at Amortized Cost Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Term loans by vintage year four Financing Receivable, Excluding Accrued Interest, Year Four, Originated, Three Years before Current Fiscal Year Interest payable Interest Payable Fair Value Disclosure This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure and may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. This item represents accrued interest payable on all forms of debt, including trade payables, that has been incurred and is unpaid as of the balance sheet date. Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Government Contracts Concentration Risk Government Contracts Concentration Risk [Member] Proceeds from share-based payment activities Proceeds from Stock Plans Loans held for sale Loans Held-for-sale, Fair Value Disclosure Asset-backed Securities Asset-backed Securities [Member] Offsetting Liabilities Offsetting Liabilities [Table Text Block] Allowance for credit loss Financing Receivable, Allowance for Credit Loss Preferred Stock Preferred Stock [Member] Other comprehensive gain (loss) Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis Quantitative Information Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Allowance for credit losses SEC Schedule, 12-09, Allowance, Loan and Lease Loss [Member] Maximum length of time over which forecasted transactions were hedged, years Maximum Length of Time Hedged in Cash Flow Hedge Net transfers from (to) loans held for investment to (from) loans held for sale Transfer Of (To) Portfolio Financing Receivables To (From) Held-For-Sale Transfer Of (To) Portfolio Financing Receivables To (From) Held-For-Sale Credit Score, FICO [Domain] Credit Score, FICO [Domain] Depositary Shares, Each Representing a 1/40th Interest in a Share of Fixed Rate Non-Cumulative Perpetual Preferred Stock, Series G Series G Preferred Stock Series G Preferred Stock [Member] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases Fixed unsecured subordinated debt Fixed Unsecured Subordinated Debt [Member] Fixed unsecured subordinated debt. Total senior and subordinated notes Senior and subordinated notes Senior And Subordinated Notes [Member] Senior and subordinated notes. Other excluding credit card Other Portfolio Segments, Excluding Credit Card [Member] Other Portfolio Segments, Excluding Credit Card [Member] External Debt and Receivable Balances of Securitization Programs Qualitative and Quantitative Information, Transferor's Continuing Involvement [Table Text Block] Foreclosed Property and Repossessed Asset Financing Receivable, Held-for-investment, Foreclosed Asset [Policy Text Block] Adjustments to reconcile net income (loss) to net cash from operating activities: Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]