Name:	bokf_AmountOfLoanPortfolioGuaranteedByUsGovernmentPreviouslySoldIntoGnmaMortgagePool
Namespace Prefix:	bokf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Name:	bokf_CommercialAbstract
Namespace Prefix:	bokf_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Name:	bokf_CreditCommitmentsAbstract
Namespace Prefix:	bokf_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Description of the first lien loan repayment terms.

No definition available.

Name:	bokf_FirstLienLoansTerms
Namespace Prefix:	bokf_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The generally accepted maximum balance outstanding at any month end during the period as of the Balance Sheet date for Home Equity Loans issued by the entity .

No definition available.

Name:	bokf_HomeEquityLoansMaximum
Namespace Prefix:	bokf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Reflects the aggregate gross carrying amount of all loans in portfolio to businesses and individuals in the state of Oklahoma.

No definition available.

Name:	bokf_LoansReceivableGrossCarryingAmountBusinessesIndividualsInOklahoma
Namespace Prefix:	bokf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Reflects the aggregate gross carrying amount of all loans in portfolio to businesses and individuals in the state of Texas.

No definition available.

Name:	bokf_LoansReceivableGrossCarryingAmountBusinessesIndividualsInTexas
Namespace Prefix:	bokf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Reflects the aggregate gross carrying amount of all loans in portfolio to businesses in the state of Oklahoma.

No definition available.

Name:	bokf_LoansReceivableGrossCarryingAmountBusinessesInOklahoma
Namespace Prefix:	bokf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Reflects the aggregate gross carrying amount of all loans in portfolio to businesses in the state of Texas.

No definition available.

Name:	bokf_LoansReceivableGrossCarryingAmountBusinessesInTexas
Namespace Prefix:	bokf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Percentage of loan receivable to total loan portfolio.

No definition available.

Name:	bokf_LoansReceivablePercentageOfTotalPortfolio
Namespace Prefix:	bokf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Reflects the percentage of the total loan portfolio to businesses and individuals in the state of Oklahoma.

No definition available.

Name:	bokf_LoansReceivablePercentageOfTotalPortfolioBusinessesIndividualsInOklahoma
Namespace Prefix:	bokf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Reflects the percentage of the total loan portfolio to businesses and individuals in the state of Texas.

No definition available.

Name:	bokf_LoansReceivablePercentageOfTotalPortfolioBusinessesIndividualsInTexas
Namespace Prefix:	bokf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Reflects the percentage of the total loan portfolio to businesses in the state of Oklahoma.

No definition available.

Name:	bokf_LoansReceivablePercentageOfTotalPortfolioBusinessesInOklahoma
Namespace Prefix:	bokf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Reflects the percentage of the total loan portfolio to businesses in the state of Texas.

No definition available.

Name:	bokf_LoansReceivablePercentageOfTotalPortfolioBusinessesInTexas
Namespace Prefix:	bokf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Maximum dollar amount of loans in this category with individual loan amount less than specified threshold.

No definition available.

Name:	bokf_MaximumAmountOfLoansWithBalancesBelowThreshold
Namespace Prefix:	bokf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Maximum debt-to-income ratio on home equity loans.

No definition available.

Name:	bokf_MaximumDebtToIncomeRatioOnHomeEquityLoans
Namespace Prefix:	bokf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the maximum debt-to-income (DTI) ratio on loans approved.

No definition available.

Name:	bokf_MaximumDebtToIncomeRatioOnLoans
Namespace Prefix:	bokf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Maximum loan amount for specified individual loans in category.

No definition available.

Name:	bokf_MaximumLoanAmountForCertainIndividualLoansInCategory
Namespace Prefix:	bokf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Minimum FICO required for home equity loan approval.

No definition available.

Name:	bokf_MinimumFicoRequiredForHomeEquityLoanApproval
Namespace Prefix:	bokf_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

Represents the minimum FICO score required for loan approval.

No definition available.

Name:	bokf_MinimumFicoRequiredForLoanApproval
Namespace Prefix:	bokf_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

Represents the minimum loan-to-value (LTV) ratio acceptable for loans to be approved.

No definition available.

Name:	bokf_MinimumLoanToValueRatioOnLoans
Namespace Prefix:	bokf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Outstanding commitments to extend credit based on existing credit policies.

No definition available.

Name:	bokf_OutstandingCommitmentsToExtendCredit
Namespace Prefix:	bokf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

An irrevocable guarantee to extend credit to a party based on current credit policies.

No definition available.

Name:	bokf_OutstandingStandbyLettersOfCredit
Namespace Prefix:	bokf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Represents the percentage of the entity's home equity loan portfolio that is comprised of junior lien loans that are distributed to revolving lines of credit.

No definition available.

Name:	bokf_PercentageOfEntitysHomeEquityLoanPortfolioThatIsComprisedOfJuniorLienLoansDistributedToRevolvingLinesOfCredit
Namespace Prefix:	bokf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Represents the percentage of the entity's home equity loan portfolio that is comprised of first lien loans.

No definition available.

Name:	bokf_PercentageOfHomeEquityLoanPortfolioComprisedOfFirstLienLoans
Namespace Prefix:	bokf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Represents the percentage of the entity's home equity loan portfolio that is comprised of junior lien loans.

No definition available.

Name:	bokf_PercentageOfHomeEquityLoanPortfolioComprisedOfJuniorLienLoans
Namespace Prefix:	bokf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Represents the percentage of the entity's home equity loan portfolio that is comprised of junior lien loans distributed to amortizing term loans.

No definition available.

Name:	bokf_PercentageOfHomeEquityLoanPortfolioComprisedOfJuniorLienLoansDistributedToAmortizingTermLoans
Namespace Prefix:	bokf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Reflects the percentage of the loan in portfolio secured by property in the state of Oklahoma.

No definition available.

Name:	bokf_PercentageOfLoanPortfolioSecuredByPropertyInOklahoma
Namespace Prefix:	bokf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Reflects the percentage of the loan in portfolio secured by property in the state of Texas.

No definition available.

Name:	bokf_PercentageOfLoanPortfolioSecuredByPropertyInTexas
Namespace Prefix:	bokf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The maximum number of years that variable rate jumbo loans will have their interest rate fixed.

No definition available.

Name:	bokf_PeriodForFixedRateOnVariableRateJumboLoansMaximum
Namespace Prefix:	bokf_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	instant

The minimum number of years that variable rate jumbo loans will have their interest rate fixed.

No definition available.

Name:	bokf_PeriodForFixedRateOnVariableRateJumboLoansMinimum
Namespace Prefix:	bokf_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	instant

Represents the maximum loan-to-value (LTV) ratio on loans approved.

No definition available.

Name:	bokf_PmaximumLoanToValueRatioOnLoans
Namespace Prefix:	bokf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Recorded investment in financing receivables that are 90 days or more past due and still accruing.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=6965416&loc=d3e5111-111524

-Subparagraph (d)

Name:	us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

No definition available.

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Gross amount under revolving lines of credit outstanding extended to a homeowner and collateralized by the equity in the home. Such lines of credit are generally subordinated to the homeowner's mortgage loan or loans. Loan proceeds are generally unrestricted as to use by the borrower.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-DEP

-Chapter 8

-Paragraph 41

-IssueDate 2006-05-01

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6375948&loc=d3e4428-111522

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 01-6

-Paragraph 13

-Subparagraph e

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(a)(3),(b))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 9

-Section 03

-Paragraph 7

-Subparagraph a, b

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher OTS

-Name Federal Regulation (FR)

-Number Title 12

-Chapter V

-Section 563c.102

-Subsection I

-Paragraph 8

-Subparagraph c(i)

-LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy. It will be removed from future versions of this taxonomy.

Name:	us-gaap_LoansAndLeasesReceivableConsumerHomeEquity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Name:	us-gaap_LoansAndLeasesReceivableDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Reflects the aggregate gross carrying amount of all categories of loans and leases held in portfolio, prior to deducting deferred income and the allowance for losses on loans and leases.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 01-6

-Paragraph 13

-Subparagraph e

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6375948&loc=d3e4428-111522

Name:	us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Reflects the carrying amount of loans deemed to be questionable as to collection on which no interest is continuing to be recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 01-6

-Paragraph 13

-Subparagraph g

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6965416&loc=d3e5111-111524

Name:	us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Name:	us-gaap_LoansAndLeasesReceivableOtherInformationAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Reflects the carrying amount of loans charging borrowers fixed rates of interest.

No definition available.

Name:	us-gaap_LoansReceivableWithFixedRatesOfInterest
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Reflects the carrying amount of loans charging borrowers variable, or adjustable, rates of interest.

No definition available.

Name:	us-gaap_LoansReceivableWithVariableRatesOfInterest
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant