Restatement [Axis] Revision of Prior Period [Axis] Municipal and other tax-exempt securities [Member] US States and Political Subdivisions Debt Securities [Member] Mortgage loans originated for sale Payments for Origination of Mortgage Loans Held-for-sale Average Yields On Comparable Short-term Taxable Securities Maximum Average Yields On Comparable Short-term Taxable Securities Maximum The average rate of yield for comparable short-term investment grade taxable security. Commitments and Contingent Liabilities [Text Block] Commitments and Contingencies Disclosure [Text Block] Change in trading and fair value option securities Increase (Decrease) in Debt Securities, Trading, and Equity Securities, FV-NI Interest-bearing cash and cash equivalents Interest-bearing cash and cash equivalents Represents money market or interest-bearing cash accounts held in other financial institutions (including the Federal Reserve); federal funds sold to other depository institutions, securities brokers or securities dealers and securities purchased under agreements to resell. Securities [Text Block] Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Deposit service charges and fees [Member] Deposit Account [Member] Assumptions to Value Mortgage Servicing Rights [Table Text Block] Assumptions to Value Mortgage Servicing Rights [Table Text Block] Assumptions to Value Mortgage Servicing Rights [Table Text Block] Loans, fixed rate of interest Loans Receivable with Fixed Rates of Interest Statistical Measurement [Domain] Statistical Measurement [Domain] Liabilities and Equity [Abstract] Liabilities and Equity [Abstract] Capital calls and distributions, net Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Retail brokerage revenue [Member] Retail brokerage revenue [Member] Retail brokerage revenue [Member] Denominator: [Abstract] Denominator: [Abstract] -- None. No documentation exists for this element. -- Personnel Labor and Related Expense Current Fiscal Year End Date Current Fiscal Year End Date To-be-announced residential mortgage-backed securities [Member] TBA Residential Mortgage-Backed Securities [Member] To-be-announed residential mortgage-backed securities [Member] Fair Value Option Securities [Line Items] Fair Value Option Securities [Line Items] [Line Items] for Fair Value Option Securities [Table] Debt Securities, Available-for-sale, Maturity, Amortized Cost, Rolling Maturity [Abstract] Debt Securities, Available-for-sale, Maturity, Amortized Cost, Rolling Maturity [Abstract] Assets [Abstract] Assets: [Abstract] Assets [Abstract] Accounting Policies [Abstract] Accounting Policies [Abstract] Loan receivables disclosure [Abstract] Loans and Leases Receivable Disclosure [Abstract] Principal amount of entered judgment against the principal individual and his wife Principal amount of entered judgment against the principal individual and his wife Principal amount of entered judgment against the principal individual and his wife Document Type Document Type Gross charge-offs against allowance for loan losses Allowance for Loan and Lease Losses, Write-offs Misuse of Revenues Pledged to Municipal Bonds [Member] Misuse of Revenues Pledged to Municipal Bonds [Member] Misuse of Revenues Pledged to Municipal Bonds [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Allowance for real estate and other repossessed assets Real Estate Owned, Valuation Allowance Effect of reallocating undistributed earnings of participating securities Undistributed Earnings (Loss) Allocated to Participating Securities, Diluted Net change in the fair value of mortgage loan commitments Change in fair value of mortgage loan commitments Represents the change in fair value of mortgage loan commitments during the period. Fair Value Assets And Liabilities Measured On A Recurring Basis [Table Text Block] Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Less: Earnings allocated to participating securities Undistributed Earnings (Loss) Allocated to Participating Securities, Basic General number of days for delivery of loans, for which the price is set by forward sales contracts, minimum (in days) Minimum Number of Days for Delivery of Forward Sales Contracts Represents the minimum number of days from the point of pricing being set to delivery of forward sales contracts. Residential mortgage [Member] Residential Portfolio Segment [Member] Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Charitable contributions to BOKF Foundation Contributions to BOKF Foundation Contributions to BOKF Foundation Impaired loans, recorded investment with related allowance Impaired Financing Receivable, with Related Allowance, Recorded Investment Retail [Member] Retail [Member] Derivative Assets, Cash Collateral Derivative Asset, Collateral, Obligation to Return Cash, Offset Business promotion Marketing and Advertising Expense Measurement Frequency [Domain] Measurement Frequency [Domain] Average shares used in computation: [Abstract] Weighted Average Number of Shares Outstanding, Basic [Abstract] Current Financing Receivable, Not Past Due Noninterest-bearing demand deposits Noninterest-bearing Deposit Liabilities, Domestic Statement [Line Items] Statement [Line Items] Loans [Text Block] Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Measurement Input Type [Domain] Measurement Input Type [Domain] Statement [Table] Statement [Table] Statistical Measurement [Axis] Statistical Measurement [Axis] Derivative Liabilities, Cash Collateral Derivative Liability, Collateral, Right to Reclaim Cash, Offset Fair Value, Nonrecurring [Member] Fair Value, Nonrecurring [Member] Weighted Average [Member] Weighted Average [Member] Fair Value Measurements, Measured On Recurring Basis, Significant Unobservable Inputs, Quantitative Information [Abstract] Fair Value Measurements, Measured On Recurring Basis, Significant Unobservable Inputs, Quantitative Information [Abstract] Fair Value Measurements, Measured On Recurring Basis, Significant Unobservable Inputs, Quantitative Information [Abstract] Financial Instrument Performance Status [Domain] Financial Instrument Performance Status [Domain] Appraised Value, as Adjusted [Member] Valuation Technique, Appraised Value as Adjusted [Member] Valuation technique calculated based on third-party appraised value. Principles of Consolidation [Policy Text Block] Consolidation, Policy [Policy Text Block] Net losses (gains) and expenses of repossessed assets, net Repossessed Assets Expense And Net Losses Amount of expense and net losses recognized during the period for repossessed assets. Summary of Mortgage Servicing Rights [Abstract] Summary of Mortgage Servicing Rights [Abstract] -- None. No documentation exists for this element. -- Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Weighted average interest rate Weighted Average Interest Rate of Loans Serviced for Others Represents the weighted average interest rate of loans servicedf for others as of the balance sheet date. Total interest revenue Interest and Dividend Income, Operating Total fees and commissions Total fees and commissions Total fees and commissions Total fees and commissions earned from providing services such as maintaining: depositor accounts; fiduciary and trust; brokerage and underwriting; mortgage; transaction cards; and other revenue such as bank owned life insurance. Capitalized mortgage servicing rights Capitalized mortgage servicing rights Represents non-cash adjustment to reconcile net income related to capitalization of mortgage servicing rights. Funds Management and Other [Member] Corporate, Non-Segment [Member] Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract] Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract] Borrowed funds Interest Expense, Short-term Borrowings Delinquency rate Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Delinquency Rate Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Delinquency Rate Mortgage Banking Revenue [Abstract] Mortgage Banking Revenue [Abstract] Mortgage Banking Revenue [Abstract] Trading revenue [Member] Gain loss on trading [Member] Gain loss on trading [Member] General number of days outstanding for residential mortgage commitments, minimum (in days) Minimum Number of Days Outstanding For Residential Mortgage Commitments Represents represents the typical minimum period for commitment to originate a residential mortgage loan to when the closed loan is sold to an investor. Measurement Frequency [Axis] Measurement Frequency [Axis] Measurement Frequency [Axis] Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value [Table] Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value [Table] Financial Instruments [Domain] Financial Instruments [Domain] Fair Value of Financial Instruments [Table Text Block] Fair Value, by Balance Sheet Grouping [Table Text Block] Residential construction and land development [Member] Residential construction and land development [Member] Residential construction and land development [Member] Gain (Loss) on Derivatives, Net Derivative, Gain (Loss) on Derivative, Net Fair Value Measurement [Domain] Fair Value Measurement [Domain] Financing Receivable, Nonaccrual, Related Allowance Financing Receivable, Nonaccrual, Related Allowance Amount of financing receivable on nonaccrual status with a related allowance. Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer Derivatives, Policy [Policy Text Block] Derivatives, Policy [Policy Text Block] Subsequent Events [Text Block] Subsequent Events [Text Block] Local Phone Number Local Phone Number Number of days for past due for loan to be considered nonperforming (in days) Number Of Days For Past Due Residential Mortgage Loans Held for Sale Represents the number of days past due for residential mortgage loans held for sale to be reported as delinquent. Investment Securities, Continuous Unrealized Loss Position, Fair Value Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value Financing Receivable, Credit Quality Indicator [Line Items] Financing Receivable, Credit Quality Indicator [Line Items] Interest-bearing cash and cash equivalents Interest-bearing Deposits in Banks and Other Financial Institutions Beginning balance - Incurred Loss Model Ending balance - Incurred Loss Model SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount Financing Receivable, Originated, 2018 Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year Income Statement Location [Domain] Income Statement Location [Domain] Cash Flows From Financing Activities: [Abstract] Net Cash Provided by (Used in) Financing Activities [Abstract] Other debt securities [Member] Other Debt Obligations [Member] Foreign exchange contracts [Member] Foreign Exchange Contract [Member] Proceeds from sale of mortgage loans held for sale Proceeds from Sale of Mortgage Loans Held-for-sale Investment Securities, Debt Maturities, Over Ten Years, Net Carrying Value Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Amortized Cost Cash and due from banks Cash and Cash Equivalents, Fair Value Disclosure Total assets Assets Funds purchased and repurchase agreements Federal Funds Purchased and Securities Sold under Agreements to Repurchase Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Significant Accounting Policies [Text Block] Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Credit Loss [Abstract] Credit Loss [Abstract] Individually measured for impairment, recorded investment Financing Receivable, Individually Evaluated for Impairment Commercial real estate [Member] Commercial Real Estate Portfolio Segment [Member] Fair Value Measurement, Measured On Non-Recurring Basis, Significant Unobservable Inputs, Quantitative Information [Abstract] Fair Value Measurement, Measured On Non-Recurring Basis, Significant Unobservable Inputs, Quantitative Information [Abstract] Fair Value Measurement, Measured On Non-Recurring Basis, Significant Unobservable Inputs, Quantitative Information [Abstract] Financing Receivable Portfolio Segment [Domain] Financing Receivable Portfolio Segment [Domain] Commercial agency mortgage-backed securities [Member] Commercial Mortgage Backed Securities [Member] Total liabilities Unfunded commitments Liabilities Entity Address, City or Town Entity Address, City or Town Internal Credit Assessment [Domain] Internal Credit Assessment [Domain] Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value Debt Securities, Available-for-sale, Unrealized Loss Position Nonaccruing substandard and doubtful [Member] Nonaccruing substandard and doubtful [Member] Nonaccruing substandard and doubtful [Member] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Residential Mortgage Loans Held For Sale [Table] Schedule of Residential Mortgage Loans Held For Sale [Table] -- None. No documentation exists for this element. -- Notional Amount of Derivatives [Abstract] Notional Disclosures [Abstract] Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months Mortgage servicing rights Beginning balance Ending balance Servicing Asset at Fair Value, Amount Fiduciary and asset management revenue [Member] Fiduciary and Trust [Member] Capital Surplus [Member] Additional Paid-in Capital [Member] Net interest revenue Interest Income (Expense), Net Deposits Interest Expense, Deposits Other assets Other Assets Asset Class [Axis] Asset Class [Axis] Investment Securities, Debt Maturities, One to Five Years, Net Carrying Value Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Amortized Cost Balance, beginning of period (in shares) Balance, end of period (in shares) Shares, Issued Internal Credit Assessment [Axis] Internal Credit Assessment [Axis] Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value Insurance brokerage revenue [Member] Insurance brokerage revenue [Member] Insurance brokerage revenue [Member] Available-for-sale Securities, Debt Maturities, Over Ten Years, Fair Value Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value Home equity [Member] Home Equity Line of Credit [Member] Common stock, shares authorized (in shares) Common Stock, Shares Authorized Mortgage production revenue [Member] Mortgage production revenue [Member] Mortgage production revenue [Member] Dilutive effect of employee stock compensation plans (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Net change in demand deposits, transaction deposits and savings accounts Net change in demand deposits, transaction deposits and savings accounts Net change in demand deposits, transaction deposits and savings accounts Overdraft fee revenue [Member] Overdraft fee revenue [Member] Overdraft fee revenue [Member] Reportable Segments [Table Text Block] Schedule of Segment Reporting Information, by Segment [Table Text Block] Loans and Leases Receivable, Net Amount [Abstract] Loans and Leases Receivable, Net Amount [Abstract] Impaired loans, related allowance Impaired Financing Receivable, Related Allowance Income Statement [Abstract] Income Statement [Abstract] Quoted prices of loans sold in securitization transactions, with a liquidity discount applied [Member] Quoted prices of loans sold in securitization transactions, with a liquidity discount applied [Member] Quoted prices of loans sold in securitization transactions, with a liquidity discount applied [Member] Accumulated Other Comprehensive Income (Loss) [Member] AOCI Attributable to Parent [Member] Investment securities, Allowance for Credit Loss Investment securities, Allowance for Credit Loss Debt Securities, Held-to-maturity, Allowance for Credit Loss Real estate and other repossessed assets, net of allowance Other Real Estate, Foreclosed Assets, and Repossessed Assets Nonspecific Allowance [Member] Unallocated Financing Receivables [Member] Escrow earnings rate - indexed to rates paid on deposit accounts with comparable average life (in hundredths) Servicing Assets At Fair Value Assumptions Used To Estimate Fair Value Escrow Earnings Rate The escrow earning rate used to estimate the fair value of servicing assets, based on rates paid on deposit accounts. Credit losses recognized on residential mortgage loans held for sale Credit losses recognized on residential mortgage loans held for sale Credit losses recognized on residential mortgage loans held for sale Bank Participation in Fraudulent Sale of Securities by Principals [Member] Bank Participation in Fraudulent Sale of Securities by Principals [Member] Bank Participation in Fraudulent Sale of Securities by Principals [Member] Derivative Liabilities, Netting Adjustments Derivative Liability, Netting Adjustments Represents amount of gross derivative liability positions offset by gross derivative asset positions due to enforceable master netting or similar arrangements. Net losses (gains) on financial instruments and other losses (gains), net Realized Investment Gains (Losses) Consolidation Items [Domain] Consolidation Items [Domain] Restatement Adjustment [Member] Revision of Prior Period, Adjustment [Member] Entity Tax Identification Number Entity Tax Identification Number Change in amount receivable on unsettled available for sale securities transactions Change in amount receivable on unsettled security transactions Change in amount receivable on unsettled security transactions. This is an investing cash flow. Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss Net income before taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Hedging Designation [Axis] Hedging Designation [Axis] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Investment Securities, Debt Maturities, Six to Ten Years, Fair Value Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Fair Value Credit Commitments [Abstract] Credit Commitments [Abstract] -- None. No documentation exists for this element. -- Financing Receivable, Troubled Debt Restructuring [Line Items] Financing Receivable, Troubled Debt Restructuring [Line Items] Performing [Member] Performing [Member] Performing Financial Instruments [Member] Available For Sale Securities [Table Text Block] Debt Securities, Available-for-sale [Table Text Block] Loss (gain) on available for sale securities, net Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax Schedule of Trading Securities [Line Items] Debt and Equity Securities, FV-NI [Line Items] Prepayment rate - based upon loan interest rate, original term and loan type, minimum Servicing Assets At Fair Value Assumptions Used To Estimate Fair Value Prepayment Speed Minimum The minimum estimated speed of prepayments of principal on financial assets which may be one of the factors applied in estimating the fair value of servicing assets. Range of fair value as a percentage of par value Range of fair value as a percentage of par value Range of fair value as a percentage of par value Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Personal trust revenue [Member] Personal trust revenue [Member] Personal trust revenue [Member] Net direct contribution Net direct contribution Represents net direct contribution of segments prior to corporate expense allocations. Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss City Area Code City Area Code Available for sale securities Available-for-sale Securities, Fair Value Debt Securities, Available-for-sale Past Due Financing Receivable, Past Due Residential mortgage loans held for sale, Fair value Fair Value of Residential Mortgage Loans Held for Sale Represents the fair value of residential mortgage loans held for sale as of the balance sheet, exclusive of mortgage commitments and forward sales contracts Residential agency mortgage-backed securities [Member] Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] Servicing revenue Mortgage Servicing Fees Servicing fees for loans secured by real property. Collectively measured for impairment, recorded investment Financing Receivable, Collectively Evaluated for Impairment Interest revenue [Abstract] Interest Income (Expense), Net [Abstract] 90 Days or More [Member] Financial Asset, Equal to or Greater than 90 Days Past Due [Member] Insurance Federal Deposit Insurance Corporation Premium Expense Class of Financing Receivable [Domain] Class of Financing Receivable [Domain] Derivative Instruments, Gain (Loss) in Statement of Earnings [Table Text Block] Derivative Instruments, Gain (Loss) [Table Text Block] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Derivative Contracts [Table Text Block] Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Fair Value Measurements [Text Block] Fair Value Disclosures [Text Block] Redemptions and distributions Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Interest rate contracts [Member] Interest Rate Swap [Member] Cumulative Effect, Period of Adoption, Adjustment Cumulative Effect, Period of Adoption, Adjustment [Member] Capital surplus Additional Paid in Capital, Common Stock Depreciation and amortization Depreciation, Amortization and Accretion, Net Subsequent Event Type [Domain] Subsequent Event Type [Domain] Marketable Securities [Abstract] Marketable Securities [Abstract] Change in other liabilities Increase (Decrease) in Other Operating Liabilities Number of individuals who purchased facilities from the principals subject to SEC New Jersey proceedings Number of individuals who purchased facilities from the principals subject to SEC New Jersey proceedings Number of individuals who purchased facilities from the principals subject to SEC New Jersey proceedings Transaction Demand Deposit Accounts Pass [Member] Pass [Member] Purchase of facilities from principals subject to SEC New Jersey proceedings [Member] Purchase of facilities from principals subject to SEC New Jersey proceedings [Member] Purchase of facilities from principals subject to SEC New Jersey proceedings [Member] Dividends paid Payments of Ordinary Dividends, Common Stock Loans Insured or Guaranteed by Government Authorities [Domain] Loans Insured or Guaranteed by Government Authorities [Domain] Variable Interest Entity, Nonconsolidated Entities, Assets Variable Interest Entity, Nonconsolidated Entities, Assets Variable Interest Entity, Nonconsolidated Entities, Assets created to tag total assets of nonconsolidated VIEs. Dividends Payable, Date of Record Dividends Payable, Date of Record Residential mortgage loans guaranteed by U.S. government agencies that became eligible for repurchase during the period Increase in U.S. government guaranteed loans eligible for repurchase Represents the non-cash increase in loans related to the right but not the obligation to repurchases loans previously sold into Ginnie Mae pools based on certain criteria and as such has effectively regained control of the asset and must recognize the loan on the balance sheet. Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions Investment management services and other revenue [Member] Investment management services and other [Member] Investment management services and other [Member] Available-for-sale Securities, Gross Unrealized Loss Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Pre-judgment interest amount of entered judgment against the principal individual and his wife Pre-judgment interest amount of entered judgment against the principal individual and his wife Pre-judgment interest amount of entered judgment against the principal individual and his wife Trading securities Interest Income, Debt Securities, Trading, Operating Deposits [Abstract] Deposits [Abstract] Goodwill Goodwill Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Trading Securities, [Table Text Block] Debt Securities, Trading, and Equity Securities, FV-NI [Table Text Block] Fair Value Measurement, Percentage of Appraised Value. Fair Value Measurement, Percentage of appraised value Fair Value Measurement, Percentage of appraised value Automated service charge and other deposit fee revenue [Member] Automated service charge and other deposit fee revenue [Member] Automated service charge and other deposit fee revenue [Member] Gain (loss) on available for sale securities, net Debt Securities, Realized Gain (Loss) Investment Securities, Debt Maturities, without Single Maturity Date, Fair Value Debt Securities, Held-to-maturity, Maturity, without Single Maturity Date, Fair Value Dividends declared per share Dividends declared (in dollars per share) Common Stock, Dividends, Per Share, Declared Fair value option securities, Net Unrealized Gain (Loss) Fair Value Option Securities Unrealized Gain or Loss Fair Value Option Securities Unrealized Gain or Loss Liquidity Discount on Mortgage Loans Qualifying for Sale to US Govt Agencies Liquidity Discount on Mortgage Loans Qualifying for Sale to US Govt Agencies Represents a liquidity discount applied to the market value of mortgage loans qualifying for sale to U.S. government agencies when a mortgage loan is ineligible for sale to U.S. government agencies. Asset-backed securities [Member] Asset-backed Securities, Securitized Loans and Receivables [Member] Fair Value by Asset Class [Domain] Asset Class [Domain] Financing Receivable, Nonaccrual [Table Text Block] Financing Receivable, Nonaccrual [Table Text Block] Assets, Fair Value Disclosure Assets, Fair Value Disclosure Stock options exercised Stock Issued, Value, Stock Options Exercised, Net of Tax Benefit (Expense) Debt Securities, Held-to-maturity [Table] Debt Securities, Held-to-maturity [Table] Institutional trust & retirement plan services revenue [Member] Institutional trust & retirement plan services revenue [Member] Institutional trust & retirement plan services revenue [Member] Entity Central Index Key Entity Central Index Key Printing, postage and supplies Supplies and Postage Expense Entity Emerging Growth Company Entity Emerging Growth Company Provision for credit losses Total provision for credit losses Provision for Loan, Lease, and Other Losses Mortgage servicing revenue [Member] Mortgage servicing revenue [Member] Mortgage servicing revenue [Member] Derivative Contract Type [Domain] Derivative Contract [Domain] Available-for-sale Securities, Debt Maturities, One to Five Years, Fair Value Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value Trading Securities, Net Unrealized Gain (Loss) Trading Securities, Net Unrealized Gains (Losses) Represents the unrealized holding gain or loss included in the fair value of trading securities as of the balance sheet date. Diluted Denominator for diluted earnings per common share (in shares) Weighted Average Number of Shares Outstanding, Diluted Subordinated debentures Subordinated Debt Fair value option securities Fair value option securities, Fair Value Fair value option securities Fair value option securities represent securities the Company has elected to carry at fair value and separately identified on the balance sheet with changes in fair value recognized in earnings as they occur. Certain residential mortgage-backed securities issued by US government agencies are held as an economic hedge of changes in the fair value of mortgage servicing rights and related derivative contracts. In addition, other securities may be held to manage interest rate risk or for deferred compensation purposes. Securities held for interest rate risk management may be economically hedged by derivative contracts not designated as hedging instruments effectively modify these fixed rate securities into variable rate securities. Financing Receivable, Credit Quality Indicator Line Items [Abstract] Financing Receivable, Credit Quality Indicator Line Items [Abstract] Financing Receivable, Credit Quality Indicator Line Items [Abstract] Investment Securities, Debt Maturities, Single Maturity Date, Fair Value Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Fair Value Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities Financing Receivable, Troubled Debt Restructuring, Postmodification Financing Receivable, Troubled Debt Restructuring, Postmodification Accruing Substandard [Member] Substandard [Member] Net change in other borrowed funds Proceeds from (Repayments of) Debt Investments by Consolidated and Nonconsolidated Entities [Domain] Investments by Consolidated and Nonconsolidated Entities [Domain] Common stock Common Stock, Value, Issued Numerator: [Abstract] Numerator: [Abstract] -- None. No documentation exists for this element. -- Available-for-sale securities [Member] Available-for-sale Securities [Member] Fees and commissions revenue [Member] Fees and commissions revenue [Member] Fees and commissions revenue [Member] Derivative Liabilities, Fair Value, Net [Abstract] Derivative Liability, Fair Value, Amount Not Offset Against Collateral [Abstract] Purchases of available for sale securities Payments to Acquire Debt Securities, Available-for-sale Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Loans, non-accrual Loans and Leases Receivable, Nonperforming, Nonaccrual of Interest Financing Receivable, Troubled Debt Restructuring, Specific Allowance Financing receivable, Troubled Debt Restructuring, Specific Allowance Financing receivable, Troubled Debt Restructuring, Specific Allowance Special Mention [Member] Special Mention [Member] Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Cash and Cash Equivalents, at Carrying Value Common stock, shares issued (in shares) Common Stock, Shares, Issued Schedule of Impaired Loans [Table] Schedule of Impaired Financing Receivable [Table] Segment Reporting [Abstract] Segment Reporting [Abstract] Total shareholders’ equity Stockholders' Equity Attributable to Parent Discounted Cash Flow [Member] Valuation Technique, Discounted Cash Flow [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Loans and Allowances for Credit Losses, Minimum No of Days After Which Past Due Non-Risk Graded Loans Are Charged Off Minimum No of Days After Which Past Due Non-Risk Graded Loans Are Charged Off Minimum number of days after which past due non-risk graded loans are charged off Time Time deposits Time Deposits Total Shareholders' Equity [Member] Parent [Member] Cash surrender value of bank-owned life insurance Bank Owned Life Insurance Other Assets [Member] Other Assets [Member] Financial Instrument [Axis] Financial Instrument [Axis] Fair Value Option Securities [Table Text Block] Fair Value Option Securities [Table Text Block] [Table Text Block] for Fair Value Option Securities [Table] Inclusion of Proprietary Investment Products as Investment Options in 401k Plan Whose Fees Were Too High and Performance Too Low [Member] Inclusion of Proprietary Investment Products as Investment Options in 401k Plan Whose Fees Were Too High and Performance Too Low [Member] Inclusion of Proprietary Investment Products as Investment Options in 401k Plan Whose Fees Were Too High and Performance Too Low [Member] Residential Mortgage Loan Commitments [Member] Residential Mortgage Loan Commitments [Member] Represent contracts related to mortgage loan commitments to purchase. Investment Securities, Debt Maturities, Single Maturity Date, Net Carrying Value Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Amortized Cost Other Comprehensive Income (Loss), before Tax [Abstract] Other Comprehensive Income (Loss), before Tax [Abstract] Restricted equity securities Federal Home Loan Bank Stock and Federal Reserve Bank Stock Loan servicing costs - annually per loan based upon loan type, performing, minimum (in dollars per loan) Servicing Assets At Fair Value Assumptions Used To Estimate Fair Value Performing Loan Service Cost Minimum The minimum cost to service a performing loan for the period used as a variable in estimating fair value. Liabilities: [Abstract] Liabilities [Abstract] Entity Address, Address Line One Entity Address, Address Line One Wealth Management [Member] Wealth Management [Member] Business segment-wealth management consulting customers. Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Entity Address, State or Province Entity Address, State or Province Residential mortgage loans held for sale, nonperforming Residential mortgage loans held for sale, nonperforming Residential mortgage loans held for sale, 90 days past due or impaired. Debt Securities, Available-for-sale, Unrealized Loss Position [Abstract] Debt Securities, Available-for-sale, Unrealized Loss Position [Abstract] Debt Securities, Available-for-sale, Unrealized Loss Position [Abstract] Other comprehensive income (loss), net of income taxes Other comprehensive income (loss) Other comprehensive income, net of income taxes Other Comprehensive Income (Loss), Net of Tax Available-for-sale Securities, Related federal and state income tax expense (benefit) Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax Interest-bearing deposits: [Abstract] Interest-bearing Deposit Liabilities [Abstract] Other expense Other Noninterest Expense Comprehensive income (loss) attributable to non-controlling interests Net income (loss) attributable to non-controlling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Earnings Per Share [Abstract] Earnings Per Share [Abstract] Net interest revenue after provision for credit losses Net interest revenue after provision for credit losses Interest Income (Expense), after Provision for Loan Loss Residential mortgage loans held for sale Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance Accumulated Unrealized Gain (Loss) on Employee Benefit Plans [Member] Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Segment Reporting Information [Line Items] Segment Reporting, Revenue Reconciling Item [Line Items] Financing Receivable, Originated, 2016 Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year Shareholders' equity: [Abstract] Stockholders' Equity Attributable to Parent [Abstract] Entity Interactive Data Current Entity Interactive Data Current Energy contracts [Member] Energy Related Derivative [Member] Loans and Allowances for Credit Losses, Maximum No of Days After Which Past Due Non-Risk Graded Loans Are Charged Off Max No of Days After Which Past Due Non-Risk Graded Loans Are Charged Off Maximum number of days after which past due non-risk graded loans are charged off Net gain on mortgage loans held for sale Net gain on mortgage loans held for sale Represents the combined realized net gain from sale of residential mortgage loans and the change in the unrealized net gain on mortgage loans held for sale during the period. Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Numerator for diluted earnings per share – income available to common shareholders Net Income (Loss) Available to Common Stockholders, Diluted Available-for-sale Securities, Debt Maturities, Allocated and Single Maturity Date, Amortized Cost Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost Manufacturing [Member] Manufacturing [Member] Class of financing receivables related to manufacturing industry. Common Stock [Member] Common Stock [Member] Product and Service [Domain] Product and Service [Domain] Consumer [Member] Consumer [Member] Business segment-consumer customers. Financing Receivable, Allowance for Credit Loss [Table] Financing Receivable, Allowance for Credit Loss [Table] Investment Securities, Debt Maturities, Net Carrying Value [Abstract] Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Restatement [Domain] Revision of Prior Period [Domain] Total Financing Receivable, before Allowance for Credit Loss Forward sales contracts [Member] Forward sales contracts [Member] Represents forward contracts to purchase mortgage loans. Available-for-sale Securities, Gross realized losses Debt Securities, Available-for-sale, Realized Loss, Excluding Other-than-temporary Impairment Stock options exercised (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Net increase (decrease) in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Net change in unrealized gain (loss) Net change in unrealized gain (loss) OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment and Tax Investment securities [Abstract] Debt Securities, Available-for-sale [Abstract] Debt Securities, Available-for-sale [Abstract] Subsequent Events [Abstract] Subsequent Events [Abstract] Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value Treasury stock, shares at cost (in shares) Treasury Stock, Shares Nonaccruing Loans [Member] Fair Value, Nonaccruing Loans [Member] Fair Value, Nonaccruing Loans [Member] Corporate trust revenue [Member] Corporate trust revenue [Member] Corporate trust revenue [Member] Cash paid for interest Interest Paid, Excluding Capitalized Interest, Operating Activities Investment Securities, Debt Maturities, One to Five Years, Fair Value Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Fair Value Brokergage and Trading Revenue Trading Gain (Loss) Total equity Balance, beginning of period Balance, end of period Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Financing Receivable, Past Due [Line Items] Financing Receivable, Past Due [Line Items] Cash paid for taxes Income Taxes Paid, Net Gain (loss) on repossessed assets, net Gain (Loss) on Sale of Assets and Asset Impairment Charges Services [Member] Services [Member] Class of financing receivables related to services industry Diluted Diluted earnings per share Earnings Per Share, Diluted Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Proceeds from sales of available for sale securities Available-for-sale Securities, Proceeds Proceeds from Sale of Debt Securities, Available-for-sale Provision Details [Abstract] Provision Details [Abstract] Provision Details [Abstract] Financing Receivable, Nonaccrual, No Allowance Financing Receivable, Nonaccrual, No Allowance Mortgage Banking Activities [Text Block] Mortgage Banking Activities [Text Block] Mortgage Banking Activities [Text Block] Outstanding principal accrued interest and other amounts upon sale of facilities securing payment of the bonds Outstanding principal accrued interest and other amounts upon sale of facilities securing payment of the bonds Outstanding principal accrued interest and other amounts upon sale of facilities securing payment of the bonds Derivative Liabilities, Gross Fair Value Derivative Liability, Fair Value, Gross Liability Receivables Accrued Investment Income Receivable TransFund EFT network revenue [Member] TransFund EFT network revenue [Member] TransFund EFT network revenue [Member] General number of days for delivery for loans, for which the price is set by forward sales contracts, maximum (in days) Maximum Number of Days for Delivery of Forward Sales Contracts Represents represents the typical maximum number of days from the point pricing is set to delivery of forward sales contracts. Net payments on derivative asset contracts Payments for (Proceeds from) Derivative Instrument, Investing Activities Average assets Average Assets for Reporting Period Amount of average assets attributed to the reportable segment for the reporting period. Maximum [Member] Maximum [Member] Non-Controlling Interests [Member] Noncontrolling Interest [Member] Loans, variable rate of interest Loans Receivable with Variable Rates of Interest Cash dividends on common stock Dividends, Common Stock, Cash Reclassification Adjustments Included in Earnings [Abstract] Reclassification Adjustments Included in Earnings [Abstract] Reclassification Adjustments Included in Earnings [Abstract] Document and Entity Information [Abstract] Document and Entity Information [Abstract] Document and Entity Information [Abstract] 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] Loan servicing costs - annually per loan based upon loan type, performing, maximum (in dollars per loan) Servicing Assets At Fair Value Assumptions Used To Estimate Fair Value Performing Loan Service Cost Maximum The maximum cost to service a performing loan for the period used as a variable in estimating fair value. Other changes to provision Other changes to provision Other changes to provision Available-for-sale Securities, Debt Maturities, Allocated and Single Maturity Date, Fair Value Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value Due on unsettled securities purchases Broker-Dealer, Payable to Other Broker-Dealer and Clearing Organization Financing Receivable, Originated, 2017 Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year Change in accrued interest, taxes and expense Increase (Decrease) in Other Accounts Payable and Accrued Liabilities Range of Interest Rates used to Value Securities Range of Interest Rates used to Value Securities Range of Interest Rates used to Value Securities Investment Securities, Debt Maturities, Less than One Year, Net Carrying Value Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Amortized Cost Restricted equity securities Other Interest and Dividend Income Mortgage Banking Revenue [Table Text Block] Mortgage Banking Revenue [Table Text Block] Mortgage Banking Revenue [Table Text Block] Investment Securities, Debt Maturities, without Single Maturity Date, Net Carrying Value Debt Securities, Held-to-maturity, Maturity, without Single Maturity Date, Amortized Cost Interest Rate Spread [Member] Interest Rate Spread [Member] Interest Rate Spread [Member] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Fair Value Measurement Inputs and Valuation Techniques [Line Items] Fair Value, Recurring [Member] Fair Value, Recurring [Member] Mortgage banking revenue [Member] Mortgage Banking [Member] Transfer to Level 3 from Level 2 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 Financing Receivable, Revolving, Converted to Term Loan Financing Receivable, Revolving, Converted to Term Loan Treasury Stock [Member] Treasury Stock [Member] Wholesale/retail [Member] Wholesale and retail [Member] Class of financing receivables related to wholesale/retail industry. Available-for-sale Securities, Debt Maturities [Abstract] Available-for-sale Securities, Debt Maturities [Abstract] Segments [Axis] Segments [Axis] Accumulated Other Comprehensive Income (Loss) [Table Text Block] Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Net realized gains on sale of mortgage loans Gain (Loss) on Sale of Mortgage Loans Fair Value, Inputs, Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Repurchase of common stock (in shares) Stock Repurchased During Period, Shares Allowance for off-balance sheet credit losses [Abstract] Allowance For Off-Balance Sheet Credit Losses [Abstract] -- None. No documentation exists for this element. -- Industrial [Member] Industrial [Member] Class of financing receivables for which repayment will come from the sale or rental of industrial facilities. Derivative contracts, net Derviative contracts, net of cash collateral, Assets, Fair value Derviative contracts, net of cash collateral, Assets, Fair value Derivative Asset Derivatives [Text Block] Derivative Instruments and Hedging Activities Disclosure [Text Block] Intangible assets, net Intangible Assets, Net (Excluding Goodwill) Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Fair Value Entity Address, Postal Zip Code Entity Address, Postal Zip Code Available-for-sale Securities, Debt Maturities, Average Expected Life of Mortgage-backed Securities Debt Securities, Available-for-sale Securities, Debt Maturities, Average Expected Life of Mortgage-backed Securities The calculated weighted-average expected life of mortgage-backed securities based on prepayment assumptions as of the balance sheet date. Change in the fair value of mortgage servicing rights due to principal payments Change in fair value of mortgage servicing rights due to loan runoff Represents the non-cash decrease in net pre-tax net income related to the change in fair value of mortgage servicing rights due to loan runoff Investments by Consolidated and Nonconsolidated Entities [Axis] Investments by Consolidated and Nonconsolidated Entities [Axis] Vesting of non-vested shares Share-based Payment Arrangement, Decrease for Tax Withholding Obligation Repurchase of common stock Payments for Repurchase of Common Stock Servicing Asset at Fair Value, Amount [Roll Forward] Servicing Asset at Fair Value, Amount [Roll Forward] Available-for-sale Securities, Debt Maturities, Six To Ten Years, Amortized Cost Basis Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Amortized Cost Entity Bankruptcy Proceedings, Reporting Current Entity Shell Company Other comprehensive income (loss) before income taxes Other comprehensive income, before income taxes Other Comprehensive Income (Loss), before Tax Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract] Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value [Abstract] Loans Interest and Fee Income, Loans and Leases Held-in-portfolio Financial Asset, Period Past Due [Axis] Financial Asset, Period Past Due [Axis] Related allowance [Abstract] Related Allowance [Abstract] Related Allowance [Abstract] -- None. No documentation exists for this element. -- Retained earnings Retained Earnings (Accumulated Deficit) Loans Insured or Guaranteed by Government Authorities [Axis] Loans Insured or Guaranteed by Government Authorities [Axis] Total deposits Deposits Fair Value Assets Measured On Recurring Basis, Significant Unobservable Inputs [Table Text Block] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Individually measured for impairment, related allowance Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment Change in provision due to changes in reasonable and supportable forecasts, primarily due to COVID-19 pandemic Change in provision due to changes in reasonable and supportable forecasts, primarily due to COVID-19 pandemic Change in provision due to changes in reasonable and supportable forecasts, primarily due to COVID-19 pandemic Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Amortized Cost Derivative Liabilities, Notional Derivative Liability, Notional Amount Gain on derivatives, net Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net Subordinated debentures Interest Expense, Subordinated Notes and Debentures Hedging Designation [Domain] Hedging Designation [Domain] U.S. government agency debentures [Member] US Treasury and Government [Member] Document Quarterly Report Document Quarterly Report Valuation Approach and Technique [Domain] Valuation Approach and Technique [Domain] Conveyance of other real estate owned guaranteed by U.S. government agencies Conveyance of other real estate owned guaranteed by US govt Represents non-cash conveyance of other real estate owned guaranteed by U.S. government agencies during period. Customer hedging revenue [Member] Customer hedging revenue [Member] Customer hedging revenue [Member] Non-Graded, Recorded Investment Non-Graded, Recorded Investment The amount of the recorded investment, for which risk grading is not used to monitor credit quality, in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. These represent small homogeneous pools primarily composed of residential and consumers as well as certain commercial loans. Financing Receivable, Nonaccrual [Line Items] Financing Receivable, Nonaccrual [Line Items] Share-based compensation APIC, Share-based Payment Arrangement, Increase for Cost Recognition Net change in unrealized gain (loss) on mortgage loans held for sale Net change in unrealized gain on mortgage loans held for sale Represents the net change in unrealized gain on mortgage loans held for sale under fair value option. Cumulative Effect, Period of Adoption, Adjusted Balance Cumulative Effect, Period of Adoption, Adjusted Balance [Member] Fees and commissions revenue from contracts with customers Revenue from Contract with Customer, Excluding Assessed Tax Off-Balance Sheet, Credit Loss, Liability [Roll Forward] Off-Balance Sheet, Credit Loss, Liability [Roll Forward] Prepayment rate - based upon loan interest rate, original term and loan type, maximum Servicing Assets At Fair Value Assumptions Used To Estimate Fair Value Prepayment Speed Maximum The maximum estimated speed of prepayments of principal on financial assets which may be one of the factors applied in estimating the fair value of servicing assets. Loans originated, net of principal collected Payments for (Proceeds from) Loans and Leases Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases Entity File Number Entity File Number Merchant services revenue [Member] Merchant services revenue [Member] Merchant services revenue [Member] Investment Securities, Gross Unrealized Loss Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss Financing Receivable Portfolio Segment [Axis] Financing Receivable Portfolio Segment [Axis] Management knowledge of Industry [Member] Management knowledge of Industry [Member] Management knowledge of industry and non-real estate collateral including but not limited to recoverable oil and gas reserves, forward-looking commodity prices, estimated operating costs Home Equity Loan [Member] Home Equity Loan [Member] Investment Securities, Debt Maturities, Less Than One Year, Fair Value Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value Document Fiscal Period Focus Document Fiscal Period Focus Fair Value of Impaired Loans as Percentage of Unpaid Principal Balance Fair Value of Impaired Loans as Percentage of Unpaid Principal Balance Fair Value of Impaired Loans as Percentage of Unpaid Principal Balance Summary of Loans by Aging Status [Table Text Block] Financing Receivable, Past Due [Table Text Block] Transaction card revenue [Member] Transaction card revenue [Member] Transaction card revenue [Member] Investment securities Interest Income, Debt Securities, Held-to-maturity Debt Securities, Available-for-sale, Realized Gain (Loss) [Abstract] Debt Securities, Available-for-sale, Realized Gain (Loss) [Abstract] Schedule of Credit Quality Indicators [Table Text Block] Financing Receivable Credit Quality Indicators [Table Text Block] Commercial [Member] Commercial Portfolio Segment [Member] Issuance of common and treasury stock, net Proceeds from Issuance of Common Stock Financial Asset, Period Past Due [Domain] Financial Asset, Period Past Due [Domain] Earnings Per Share [Table Text Block] Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Fair Value Assets Measured on Recurring Basis Unobservable Reconciliation [Roll Forward] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Allowance for loan losses Beginning balance - Incurred Loss Model Ending balance - Incurred Loss Model Total Loans and Leases Receivable, Allowance Amendment Flag Amendment Flag Net cash provided by (used in) operating activities Net Cash Provided by (Used in) Operating Activities Financing Receivable, Nonaccrual Nonaccrual Financing Receivable, Nonaccrual Derivative Instrument [Axis] Derivative Instrument [Axis] Summary of Mortgage Servicing Rights [Table Text Block] Summary of Mortgage Servicing Rights [Table Text Block] Tabular disclosure of the summary of residential mortgage servicing rights as measured at balance sheet date. Primary secondary mortgage rate spread Primary secondary mortgage rate spread Mortgage rate spread between the primary and secondary market. Financing Receivable, Past Due [Table] Financing Receivable, Past Due [Table] Segments [Domain] Segments [Domain] Personal [Member] Consumer Portfolio Segment [Member] Available-for-sale Securities, Amortized Cost Debt Securities, Available-for-sale, Amortized Cost Other trading securities Other Trading Securities [Member] Other debt or equity trading securities Available-for-sale Securities, Gross Unrealized Gain Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Equity option contracts [Member] Equity Swap [Member] Nonperforming Financial Instruments [Member] Nonperforming Financial Instruments [Member] Gain (loss) recognized in earnings Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings Marketability adjustments off appraised value Marketability adjustments off appraised value [Domain] Marketability adjustments off appraised value [Domain] Income Statement Location [Axis] Income Statement Location [Axis] Public finance [Member] Public Finance [Member] Class of financing receivables related to public finance Stockholders' Equity Note [Abstract] Stockholders' Equity Note [Abstract] Derivative, Notional Amount Derivative, Notional Amount Amortization of intangible assets Amortization of Intangible Assets Specific Allowance [Member] Specific Allowance [Member] Financing receivables and related allowance that have been spefically allocated to a portfolio segment. Entity Current Reporting Status Entity Current Reporting Status Derivative, Net fair value Derivative, Fair Value, Net Gain (loss) on financial instruments, net Gain (Loss) on Financial Instruments, Net Represents gain (loss) on financial instruments, net, used for segment reporting purposes on a summary basis. Includes those gains and losses from derivative contracts, fair value option securities and available for sale securities. Also includes in other-than-temporary impairment losses recognized in earnings. Other liabilities Other Liabilities Reportable Segments [Text Block] Segment Reporting Disclosure [Text Block] Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract] Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss [Abstract] Non-vested shares awarded, net (in shares) Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures Past Due 90 Days or More and Accruing Financing Receivable, 90 Days or More Past Due, Still Accruing Net change in derivative margin accounts Net change in derivative margin accounts The net change in derivative margin accounts. Recorded investment [Abstract] Recorded Investment [Abstract] Recorded Investment [Abstract] -- None. No documentation exists for this element. -- Liquidity discount [Member] Measurement Input, Discount for Lack of Marketability [Member] Entity Small Business Entity Small Business Provision for loan losses - incurred Provision for Loan and Lease Losses Previously Reported [Member] Previously Reported [Member] Total interest expense Interest Expense Provision for off-balance sheet credit risk Off-Balance Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal) Entity Filer Category Entity Filer Category Proceeds from disposition of assets Proceeds from Sale of Productive Assets Product and Service [Axis] Product and Service [Axis] Non-vested shares awarded, net Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net Loans, Number of Days After Notification of Chapter 7 Bankruptcy Non-Risk Graded Loan is Placed on Nonaccruing Status Loans, Number of Days After Notification of Chapter 7 Bankruptcy Non-Risk Graded Loan is Placed on Nonaccruing Status The number of days following notification of a borrowers Chapter 7 bankruptcy that a non-risk graded loan is placed on nonaccruing status. Valuation Approach and Technique [Axis] Valuation Approach and Technique [Axis] Litigation Settlement [Abstract] Litigation Settlement [Abstract] Total customer risk management programs Customer Risk Management Programs [Member] Represents total derivative contracts in customer risk management programs. Total production revenue Mortgage Production Revenue Total gain (loss) on mortgage loans held for sale, including mortgage loan commitments and forward sales contracts. Numerator for basic earnings per share – income available to common shareholders Net Income (Loss) Available to Common Stockholders, Basic Permanent Residential Mortgage [Member] Permanent Residential Mortgage [Member] Class of financing receivables related to mortgages of permanent residences. Financing Receivable, Allowance for Credit Loss [Roll Forward] Financing Receivable, Allowance for Credit Loss [Roll Forward] Internal risk management programs [Member] Internal Risk Management Programs [Member] Represents program to manage interest rate sensitivity, as part of its economic hedge of the changes in the fair value of mortgage servicing rights and as an economic hedge of trading securities. Components of Residential Mortgage Loans Held for Sale [Abstract] Components of Residential Mortgage Loans Held for Sale [Abstract] Represents the individual components of residential mortgage loans held for sale Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Debt Securities, Available-for-sale, Maturity, Fair Value, Rolling Maturity [Abstract] Debt Securities, Available-for-sale, Maturity, Fair Value, Rolling Maturity [Abstract] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value, Recurring and Nonrecurring [Table] Document Fiscal Year Focus Document Fiscal Year Focus Beginning balance - CECL Ending balance - CECL Financing Receivable, Allowance for Credit Loss Investment Securities, Debt Maturities, Average Expected Life of Mortgage-backed Securities Held-to-maturity Securities, Debt Maturities, Average Expected Life of Mortgage-backed Securities The calculated weighted-average expected life of mortgage-backed securities held to maturity based on prepayment assumptions as of the balance sheet date. Net unrealized (gains) losses from derivative contracts Unrealized Gain (Loss) on Derivatives Available-for-sale Securities, Gross realized gains Debt Securities, Available-for-sale, Realized Gain Net loans and bank premises transferred to repossessed real estate and other assets Real Estate Owned, Transfer to Real Estate Owned Operating Segments [Member] Operating Segments [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Mortgage banking revenue [Member] Mortgage banking revenue [Member] Represents Mortgage banking revenue income statement line item. Adjustments to reconcile net income to net cash used in operating activities: [Abstract] Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Derivative contracts, net Derivative Liabilities, Fair Value, Net of Cash Collateral Derivative contracts, net of cash collateral, Liabilities, Fair Value Derivative Liability Interest-bearing cash and cash equivalents Interest income, Interest-bearing cash and cash equivalents Interest earned from money market and other interest-bearing accounts held with domestic financial institutions, from excess federal funds sold to another commercial bank requiring such for its legal reserve requirements and from securities purchased under agreements to resell. Litigation Case [Axis] Litigation Case [Axis] Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Loan servicing costs - annually per loan based upon loan type, foreclosure, maximum (in dollars per loan) Servicing Assets At Fair Value Assumptions Used to Estimate Fair Value Foreclosure Loan Service Cost Maximum Servicing Assets At Fair Value Assumptions Used to Estimate Fair Value Foreclosure Loan Service Cost Maximum Discount rate - risk-free rate plus a market premium (in hundredths) Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Discount Rate Debt Securities, Trading, and Equity Securities, FV-NI [Abstract] Debt Securities, Trading, and Equity Securities, FV-NI [Abstract] Mortgage Banking [Abstract] Mortgage Banking [Abstract] Internally Risk Graded, Allowance Internally Risk Graded, Allowance The amount of the allowance for credit losses on recorded investment, that is internally risk graded, in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Impaired loans [Abstract] Loan and Lease Receivables, Impaired [Abstract] Net proceeds on derivative liability contracts Payments for (Proceeds from) Derivative Instrument, Financing Activities Derivative Assets, Netting Adjustments Derivative Asset, Netting Adjustments Represents amount of gross derivative asset positions offset by gross derivate liability due to enforceable master netting or similar agreements. Variable Interest Entity, Not Primary Beneficiary [Member] Variable Interest Entity, Not Primary Beneficiary [Member] Subsequent Event [Member] Subsequent Event [Member] Other operating expense [Abstract] Noninterest Expense [Abstract] Reclassification, Policy [Policy Text Block] Reclassification, Comparability Adjustment [Policy Text Block] Outstanding standby letters of credit Letters of Credit Outstanding, Amount Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract] Debt Securities, Held-to-maturity, Maturity, Fair Value, Rolling Maturity [Abstract] Summary of Impaired Loans [Table Text Block] Impaired Financing Receivables [Table Text Block] Loans, Number of Days Past Due for a Non-Risk Graded Loan to be Placed on Nonaccruing Status Loans, Number of Days Past Due for a Non-Risk Graded Loan to be Placed on Nonaccruing Status Represents the number of days past due a non-risk graded loan has to be in order to be placed on nonaccruing status. Revenue [Policy Text Block] Revenue [Policy Text Block] Additions Servicing Asset at Fair Value, Additions Available-for-sale Securities, Debt Maturities, Less than One Year, Amortized Cost Basis Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Amortized Cost Document Period End Date Document Period End Date Loans and Allowance for Credit Losses [Abstract] Loans and Allowance for Credit Losses [Abstract] Loans and Allowance for Credit Losses [Abstract] Entity Registrant Name Entity Registrant Name Estimate of Fair Value, Fair Value Disclosure [Member] Estimate of Fair Value Measurement [Member] Other gains, net Gain (Loss) on Disposition of Assets Net occupancy and equipment Occupancy, Net Financing Receivable, Troubled Debt Restructuring, Recorded Investment Financing Receivable, Troubled Debt Restructuring Change in fair value due to principal payments Change in fair value due to loan runoff The decrease in fair value as a result of loan runoff. Loans and Allowances for Credit Losses, Loans [Policy Text Block] Policy Loans Receivable, Policy [Policy Text Block] Residential Mortgage Backed Securities [Member] Residential Mortgage Backed Securities [Member] Financing Receivable, Allowance for Credit Loss [Line Items] Financing Receivable, Allowance for Credit Loss [Line Items] Fair Value Option Securities [Table] Fair Value Option Securities [Table] Fair Value Option Securities [Table] Comprehensive income attributable to BOK Financial Corp. shareholders Comprehensive Income (Loss), Net of Tax, Attributable to Parent Healthcare [Member] Health Care [Member] Receivable on unsettled securities sales Receivables from Brokers-Dealers and Clearing Organizations Repurchase of common stock Treasury Stock, Value, Acquired, Par Value Method Net income Net income Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Disaggregation of Fees and Commissions Revenue [Table Text Block] Disaggregation of Revenue [Table Text Block] Proceeds from sales Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales Schedule of Investment (Held-to-Maturity) Securities [Line Items] Schedule of Held-to-maturity Securities [Line Items] Loans, net of allowance Loans, net of allowance Loans and Leases Receivable, Net Amount Trading securities Debt Securities, Trading, and Equity Securities, FV-NI Proceeds from maturities or redemptions of investment securities Proceeds from Maturities, Prepayments and Calls of Held-to-maturity Securities Share-based compensation Share-based Payment Arrangement, Noncash Expense Purchases of assets Payments to Acquire Productive Assets Net interest revenue (expense) from internal sources NIR (expense) from internal sources Amount of interest revenue earned or paid on funds loaned to or borrowed from the funds management unit net of interest expense (cost of borrowed funds accounted for as interest) from internal sources. Change in amount due on unsettled available for sale securities transactions Proceeds from (Payments for) Other Financing Activities Loan servicing costs - annually per loan based upon loan type, delinquent, maximum (in dollars per loan) Servicing Assets At Fair Value Assumptions Used to Estimate Fair Value Delinquent Loan Svc Cost Maximum Servicing Assets At Fair Value Assumptions Used to Estimate Fair Value Delinquent Measurement Input Type [Axis] Measurement Input Type [Axis] Change in fair value due to market assumption changes Asset at Fair Value, Changes in Fair Value Resulting from Changes in Assumptions Trading securities Debt Securities, Trading Derivative Instruments, Gain (Loss) by Hedging Relationship, by Income Statement Location, by Derivative Instrument Risk [Table] Derivative Instruments, Gain (Loss) [Table] Financing Receivable, Nonaccrual [Table] Financing Receivable, Nonaccrual [Table] Fixed Maturity Securities [Member] Fixed Income Securities [Member] Less: Participating securities included in weighted average shares (in shares) Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights Net amortization of discounts and premiums Accretion (Amortization) of Discounts and Premiums, Investments Balance, beginning of period Balance, end of period Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Residential mortgage loans held for sale Interest and Fee Income, Loans Held-for-sale, Mortgages Net losses and operating expenses of repossessed assets Gains (Losses) on Sales of Other Real Estate Other commercial and industrial [Member] Other Commercial and Industrial [Member] Class of financing receivables related to other commercial and industrial industry. Equity Components [Axis] Equity Components [Axis] Total other operating revenue Other operating revenue Noninterest Income Available-for-sale Securities, Debt Maturities, One to Five Years, Amortized Cost Basis Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after One Through Five Years, Amortized Cost Minimum [Member] Minimum [Member] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Commercial account service charge revenue [Member] Commercial account service charge revenue [Member] Commercial account service charge revenue [Member] Net income (loss) attributable to non-controlling interests Net Income (Loss) Attributable to Noncontrolling Interest Mortgage banking costs Mortgage banking costs Expense related to mortgage banking activities including amortization of capitalized mortgage servicing rights, provision for losses on mortgage loans sold with recourse and other mortgage banking expenses. Asset-backed securities Asset-backed Securities [Member] Securities, Fair Value Option Securities [Abstract] Securities, Fair Value Option Securities [Abstract] Securities, Fair Value Option Securities [Abstract] Provision for off-balance sheet credit losses Provision for Other Credit Losses Cash Flows From Operating Activities: [Abstract] Net Cash Provided by (Used in) Operating Activities [Abstract] Shareholders' Equity [Text Block] Stockholders' Equity Note Disclosure [Text Block] Recoveries of loans previously charged off Financing Receivable, Allowance for Credit Loss, Recovery Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value [Table Text Block] Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value [Table Text Block] Proceeds from maturities or redemptions of available for sale securities Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-sale Residential mortgage loans held for sale [Member] Residential Mortgage Loans Held for Sale [Member] Represents financial statement line item Residential Mortgage Loans Held for Sale Investment Securities, fair value Investment Securities, Fair Value Debt Securities, Held-to-maturity, Fair Value Number of principals in SEC New Jersey proceedings Number of principals in SEC New Jersey proceedings Number of principals in SEC New Jersey proceedings Allowance for off-balance sheet credit losses [Roll Forward] SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] Segments Reporting Information [Table] Reconciliation of Revenue from Segments to Consolidated [Table] Judicial Ruling [Member] Judicial Ruling [Member] Impaired loans, unpaid principal balance Impaired Financing Receivable, Unpaid Principal Balance Investment Securities, Gross Amortized Cost Debt Securities, Held-to-maturity, gross Amount of investment in debt security measured at amortized cost (held-to-maturity) before allowance for credit losses Other borrowings Other Borrowings Litigation Settlement, Amount Awarded to Other Party Litigation Settlement, Amount Awarded to Other Party Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items] Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items] Components of Residential Mortgage Loans Held For Sale [Table Text Block] Residential Mortgage Loans Held For Sale [Table Text Block] Tabular disclosure of mortgage loans to individuals not classified as held for investment but are held-for-sale. Financing Receivable, Revolving Financing Receivable, Revolving Savings Deposits, Savings Deposits Other operating revenue [Abstract] Other Nonoperating Income (Expense) [Abstract] Total other operating expense Other operating expense Noninterest Expense Consolidation Items [Axis] Consolidation Items [Axis] Impaired loans, recorded investment, total Impaired Financing Receivable, Recorded Investment Derivative Assets, Fair Value, Net [Abstract] Derivative Asset, Fair Value, Amount Not Offset Against Collateral [Abstract] Not Designated as Hedging Instrument [Member] Not Designated as Hedging Instrument [Member] General number of days outstanding for residential mortgage commitments, maximum (in days) Maximum Number of Days Outstanding For Residential Mortgage Commitments Represents represents the typical maximum period for commitment to originate a residential mortgage loan to when the closed loan is sold to an investor. Deposits with no stated maturity Deposits No Stated Maturity 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. May be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. May be used in both the balance sheet and disclosure in the same submission. Represents time deposits with no stated maturity as presented on the statement of financial position. 30 to 59 Days [Member] Financial Asset, 30 to 59 Days Past Due [Member] Weighted average shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic and Diluted Dividends Payable, Date to be Paid Dividends Payable, Date to be Paid Dividends Payable, Date Declared Dividends Payable, Date Declared Investment Securities, Debt Maturities [Abstract] Debt Securities, Held-to-maturity, Maturity [Abstract] Data processing and communications Communications and Information Technology Gain (loss) on fair value option securities, net Gain on fair value option securities, net Gain (loss) included in earning for the period related fair value option securities primarily held as an economic hedge of the changes in the fair value of mortgage servicing rights. Fair Value Measurement Inputs and Valuation Techniques [Table] Fair Value Measurement Inputs and Valuation Techniques [Table] Financing Receivable, Impaired [Line Items] Financing Receivable, Impaired [Line Items] Remaining term (in months) Residential Mortgage Loans Serviced Weighted Average Remaining Term Represents the weighted average remaining term of mortgage loans being serviced fro others. Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Derivative Assets, Gross Fair Value Derivative Asset, Fair Value, Gross Asset Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value Assets Measured on Nonrecurring Basis [Table Text Block] Fair Value Measurements, Nonrecurring [Table Text Block] Financing Receivable, Originated, 2015 or Prior Financing Receivable, Originated, More than Five Years before Current Fiscal Year Check card revenue [Member] Check card fee revenue [Member] Check card fee revenue [Member] Financing Receivable, Troubled Debt Restructuring [Table] Financing Receivable, Troubled Debt Restructuring [Table] Derivative Liabilities, Net Fair Value Before Cash Collateral Derivative Liability, Net Fair Value Before Cash Collateral Represents net derivative liability before consideration of right to reclasim cash collateral under master netting or similar arrangements. Change in receivables Increase (Decrease) in Receivables Available-for-sale Securities, Debt Maturities, Weighted Average Maturity Debt Securities, Available-for-sale Securities, Debt Maturities, Weighted Average Maturity Represents the the contractual weighted average maturity (weighted by amount of the security) for this portion of the available-for-sale securities portfolio. Derivative Assets, Notional Derivative Asset, Notional Amount Real estate and other repossessed assets [Member] Fair Value, Real estate and other repossessed assets [Member] Fair Value, Real estate and other repossessed assets [Member] Other Liabilities [Member] Other Liabilities [Member] Cumulative Effect, Period of Adoption [Axis] Cumulative Effect, Period of Adoption [Axis] Litigation Case [Domain] Litigation Case [Domain] Basic Basic earnings per share Earnings Per Share, Basic Other commercial real estate [Member] Other Commercial Real Estate [Member] Class of financing receivables for which repyament is expected from the sale or rental of other commercial real estate properties. Financial Instrument Performance Status [Axis] Financial Instrument Performance Status [Axis] Disgorged fees Disgorged fees Represents fees disgorged as a result of a settlement with a regulatory agency. Other revenue [Member] Financial Service, Other [Member] Accumulated Net Unrealized Gain (Loss) on Available for Sale Securities [Member] AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member] Loss Contingency, Number of Plaintiffs Loss Contingency, Number of Plaintiffs Balance Sheet Location [Axis] Balance Sheet Location [Axis] Derivative Assets, Net Fair Value Before Cash Collateral Derivative Assets, Net Fair Value Before Cash Collateral Represents net derivative assets before offsetting the obligation to return cash collateral under a master netting or similar arrangement. Loss Contingency [Abstract] Loss Contingency [Abstract] Schedule of Loans by Portfolio Segment [Table Text Block] Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Number of residential mortgage loans serviced for others Residential Mortgage Loans Serviced Number Of Loans Indicates the number of mortgage loans being serviced. Professional fees and services Professional Fees Fees and commission revenue not from contracts with customers Fees and commission revenue not from contracts with customers Represents fees and commissions revenue not in the scope of ASC 606, Revenue from Contracts with Customers, related to financial instruments or from contractual rights and obligations within the scope of other applicable accounting guidance. Non-controlling interests Stockholders' Equity Attributable to Noncontrolling Interest Residential non-agency mortgage-backed securities [Member] Mortgage-backed Securities, Issued by Private Enterprises [Member] Cash Flows From Investing Activities: [Abstract] Net Cash Provided by (Used in) Investing Activities [Abstract] US Government Agency Insured Loans [Member] US Government Agency Insured Loans [Member] Available-for-sale Securities, Debt Maturities, Less than One Year, Fair Value Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling within One Year, Fair Value Fair Value Inputs, Fair Value Measured On a Recurring Basis, Quantitative Information [Table Text Block] Fair Value Inputs, Fair Value Measured On a Recurring Basis, Quantitative Information [Table Text Block] Fair Value Inputs, Fair Value Measured On a Recurring Basis, Quantitative Information [Table Text Block] Litigation Status [Axis] Litigation Status [Axis] Financing Receivable, Impaired, Troubled Debt Restructuring, Write-down Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down Cash and due from banks Cash and Due from Banks Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Total liabilities and equity Liabilities and Equity Loss Contingencies [Line Items] Loss Contingencies [Line Items] Accumulated other comprehensive gain Balance, Beginning of Period Balance, End of Period Accumulated Other Comprehensive Income (Loss), Net of Tax Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Investment Securities (Held-to-Maturity) [Table Text Block] Debt Securities, Held-to-maturity [Table Text Block] Excludes employee stock options with exercise prices greater than current market price. Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Investment Securities, Debt Maturities, Over Ten Years, Fair Value Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Fair Value Equity Component [Domain] Equity Component [Domain] Outstanding principal, accrued interest and other amounts required by bond documents Outstanding principal, accrued interest and other amounts required by bond documents Outstanding principal, accrued interest and other amounts required by bond documents Premises and equipment, net Property, Plant and Equipment, Net Unpaid principal balance Residential Mortgage Loans Held For Sale Unpaid Principal Balance, Gross Unpaid principal balance of loans held for sale. Net income attributable to BOK Financial Corporation shareholders Net income attributable to BOK Financial Corp. shareholders Net Income (Loss) Attributable to Parent Investment banking revenue [Member] Investment banking revenue [Member] Investment banking revenue [Member] Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Provision for loan losses - CECL Financing Receivable, Credit Loss, Expense (Reversal) Schedule of Trading Securities [Table] Debt Securities, Trading, and Equity Securities, FV-NI [Table] Disposals Servicing Asset at Fair Value, Disposals Corporate card revenue [Member] Corporate card revenue [Member] Corporate card revenue Servicing Assets at Fair Value, Assumptions Used to Estimate Fair Value [Abstract] Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value [Abstract] Investment Securities, Gross Unrealized Gain Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain Paycheck Protection Program Paycheck Protection Program [Member] Loans created under the SBA's Paycheck Protection Program Investment securities, net of allowance Investments securities, Amortized Cost, Net of Allowance Debt Securities, Held-to-maturity Fair Value Inputs, Fair Value Measured On a Nonrecurring Basis, Quantitative Information [Table Text Block] Fair Value Inputs, Fair Value Measured On a Nonrecurring Basis, Quantitative Information [Table Text Block] Fair Value Inputs, Fair Value Measured On a Nonrecurring Basis, Quantitative Information [Table Text Block] Net change in the fair value of forward sales contracts Change in the fair value of forward sales commitments Represents the change in the fair value of forward sales commitments considered to be derivative instruments during the period. Schedule of Residential Mortgage Loans Held For Sale [Line Items] Schedule of Residential Mortgage Loans Held For Sale [Line Items] Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Office [Member] Office [Member] Class of financing receivables related for which repayment will come from the sale or rental of office space. Trading [Member] Trading [Member] Trading [Member] Financing Receivable, Credit Quality Indicator [Table] Financing Receivable, Credit Quality Indicator [Table] Collectively measured for impairment, related allowance Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment Change in fair value of mortgage servicing rights Segment Reporting, Change in Fair Value of Mortgage Servicing Rights Represents the change in the fair value of mortgage servicing rights used for segment reporting purposes. Financing Receivable, Originated, 2020 Financing Receivable, Year One, Originated, Current Fiscal Year Supplemental Cash Flow Information: [Abstract] Supplemental Cash Flow Information [Abstract] Non-Graded, Allowance Non-Graded, Allowance The amount of the allowance for credit losses on recorded investment that is not internally risk graded, in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Outstanding commitments to extend credit Unused Commitments to Extend Credit Debt Securities, Held-to-maturity [Abstract] Debt Securities, Held-to-maturity [Abstract] Fair value option securities Interest revenue on fair value option securities Interest income from fair value option securities that the Company has elected to carry at fair value and separately identify in the Consolidated Balance Sheets with changes in the fair value recognized in earnings as they occur. Change in fair value of mortgage servicing rights Change in fair value of mortgage servicing rights due to market assumption changes Mortgage Servicing Rights (MSR) Impairment (Recovery) Beginning balance - CECL Ending balance - CECL Off-Balance Sheet, Credit Loss, Liability Loans to individuals [Member] Loans to individuals [Member] Portfolio segment of the company's total financing receivables related to loans to individuals. Pledged Assets Separately Reported, Securities Pledged as Collateral, at Fair Value Pledged Assets Separately Reported, Securities Pledged as Collateral, at Fair Value Loans Total Total Loans and Leases Receivable, Gross U.S. Treasury [Member] US Treasury Securities [Member] Federal and state income taxes Other Comprehensive Income (Loss), Tax Investment Securities, Debt Maturities, Six to Ten Years, Net Carrying Value Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Amortized Cost Loans, Number of Days After Notification of Chapter 7 Bankruptcy Non-Risk Graded Loan is Charged Off Loans, Number of Days After Notification of Chapter 7 Bankruptcy Non-Risk Graded Loan is Charged Off Represents the number of days after notification of Chapter 7 bankruptcy for a non-risk graded loan to be charged off Available-for-sale Securities, Debt Maturities, Six to Ten Years, Fair Value Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after Five Through Ten Years, Fair Value Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Loan servicing costs - annually per loan based upon loan type, foreclosure, minimum (in dollars per loan) Servicing Assets at Fair Value Assumptions Used to Estimate Fair Value Foreclosure Loan Service Cost Minimum Servicing Assets at Fair Value Assumptions Used to Estimate Fair Value Foreclosure Loan Service Cost Minimum Commercial [Member] Commercial [Member] Business segment-commercial customers. Financing Receivable, Troubled Debt Restructuring, Performing in Accordance With Modified Terms Troubled Debt Financing Receivable Modification Performing According To Modified Terms Represents the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructuring and are performing according to modified terms. Investment Securities, Debt Maturities, Weighted Average Maturity Held-to-maturity Securities, Debt Maturities, Weighted Average Maturity Represents the weighted average maturity (weighted by amount of the security) of all securities in this investment type. Other comprehensive income (loss) Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Financing receivable, recorded investment, aging [Abstract] Financing Receivable, Recorded Investment, Aging [Abstract] Basis of Accounting, Policy [Policy Text Block] Basis of Accounting, Policy [Policy Text Block] Brokerage and trading revenue [Member] Brokerage and trading revenue [Member] Brokerage and trading revenue [Member] Financing Receivable, Originated, 2019 Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year Basic Denominator for basic earnings per common share (in shares) Weighted Average Number of Shares Outstanding, Basic Investment Securities, Continuous Unrealized Loss Position [Abstract] Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract] Schedule of Accumulated Other Income (Loss) [Abstract] Schedule of Accumulated Other Comprehensive Income [Roll Forward] -- None. No documentation exists for this element. -- Loss Contingencies [Table] Loss Contingencies [Table] Carrying (Reported) Amount, Fair Value Disclosure [Member] Reported Value Measurement [Member] Internally Risk Graded, Recorded Investment Internally Risk Graded, Recorded Investment The amount of the recorded investment, that is internally risk graded on credit quality, in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Fees and Commissions Revenue [Text Block] Revenue from Contract with Customer [Text Block] Right-of-use assets obtained in exchange for operating lease liabilities Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Federal and state income taxes Income Tax Expense (Benefit) Derivative Instruments and Hedging Activities Disclosure [Abstract] Cumulative Effect, Period of Adoption [Domain] Cumulative Effect, Period of Adoption [Domain] Derivative Instrument Detail [Abstract] Derivative Instrument Detail [Abstract] Loan servicing costs - annually per loan based upon loan type, delinquent, minimum (in dollars per loan) Servicing Assets at Fair Value Assumptions Used to Estimate Fair Value Delinquent Loan Service Cost Minimum Servicing Assets at Fair Value Assumptions Used to Estimate Fair Value Delinquent Loan Service Cost Minimum Other borrowed funds Other Liabilities, Fair Value Disclosure Available-for-sale Securities, Debt Maturities, Over Ten Years, Amortized Cost Basis Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Rolling after 10 Years, Amortized Cost Change in other assets Increase (Decrease) in Other Operating Assets Agricultural contracts [Member] Agricultural Contracts [Member] Trading in a derivative instrument whose primary underlying risk is tied to agricultural commodity prices. Net interest revenue from external sources NIR (expense) from external sources Amount of interest revenue, primarily from loans and securities net of interest expense (cost of borrowed funds accounted for as interest) from external sources. Class of Financing Receivable [Axis] Class of Financing Receivable [Axis] Financing Receivable, Nonaccrual, With Allowance Financing Receivable, Nonaccrual, With Allowance Amount of financing receivable on nonaccrual status with an allowance. Alleged total of judgment against nursing home operator Alleged total of judgment against nursing home operator Alleged total of judgment against nursing home operator Outstanding principal balance of residential mortgage loans serviced for others Residential Mortgage Loans Serviced Outstanding Principal Dollar amount of principal outstanding on mortgage loans being serviced. Accrued interest, taxes and expense Accounts Payable and Accrued Liabilities Retained Earnings [Member] Retained Earnings [Member] Measurement Basis [Axis] Measurement Basis [Axis] Impaired loans, recorded investment with no related allowance Impaired Financing Receivable, with No Related Allowance, Recorded Investment Loans charged off Financing Receivable, Allowance for Credit Loss, Writeoff Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Pending Litigation [Member] Pending Litigation [Member] Energy [Member] Energy [Member] Class of financing receivables related to energy industry Document Transition Report Document Transition Report Rollforward of Allowance For Loan Losses And Accrual for Off-Balance Sheet Credit Losses [Table Text Block] Financing Receivable, Allowance for Credit Loss [Table Text Block] Activity in Capitalized Mortgage Servicing Rights [Table Text Block] Schedule of Servicing Assets at Fair Value [Table Text Block] 60 to 89 Days [Member] Financial Asset, 60 to 89 Days Past Due [Member] General business [Member] General business member [Member] General business member [Member] Litigation Status [Domain] Litigation Status [Domain] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Loans and Allowances for Credit Losses, Allowances for Credit Losses [Policy Text Block] Loans and Leases Receivable, Allowance for Loan Losses Policy [Policy Text Block] Treasury stock Treasury Stock, Value Net change in time deposits Increase (Decrease) in Time Deposits Earnings Per Share [Text Block] Earnings Per Share [Text Block] Interest expense [Abstract] Interest Expense [Abstract] Vesting of non-vested shares (in shares) Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation